Cardiac Rehabilitation: Outpatient

Number: 0021

Policy

Aetna considers outpatient (Phase II) cardiac rehabilitation medically necessary when the eligibility and program description are met as described below.

Eligibility

Aetna considers a medically supervised outpatient Phase II cardiac rehabilitation program medically necessary for selected members when it is individually prescribed by a physician within a 12-month window after any of the following documented diagnoses:

  • Acute myocardial infarction within the preceding 12 months; or 
  • Chronic stable angina pectoris unresponsive to medical therapy which prevents the member from functioning optimally to meet domestic or occupational needs (particularly with modifiable coronary risk factors or poor exercise tolerance); or 
  • Coronary artery bypass grafting (coronary bypass surgery, CABG); or
  • Following surgical septal myectomy via thoracotomy; or 
  • Heart transplantation or heart-lung transplantation; or
  • Major pulmonary surgery, great vessel surgery, or MAZE arrhythmia surgery; or 
  • Percutaneous coronary vessel remodeling (i.e., percutaneous transluminal coronary angioplasty (PTCA), atherectomy, stenting); or
  • Placement of a ventricular assist device; or 
  • Sustained ventricular tachycardia or fibrillation, or survivors of sudden cardiac death; or 
  • Valve replacement or repair; or
  • Stable congestive heart failure (CHF) with left ventricular ejection fraction (LVEF) of 35% or less and New York Heart Association (NYHA) class II to IV symptoms despite being on optimal heart failure therapy for at least 6 weeks; stable CHF is defined as CHF in persons who have not had recent (less than or equal to 6 weeks) or planned (less than or equal to 6 months) major cardiovascular hospitalizations or procedures.

Program Description

  • Physician-prescribed exercise each day cardiac rehabilitation items and services are furnished; and
  • Provides up to a maximum of two 1-hour sessions per day for up to 36 sessions over a period of 36 weeks of supervised exercise with continuous telemetry monitoring (frequency generally consists of 2 to 3 sessions per week for 12 to 18 weeks); and
  • Program is under the direct supervision of a physician or other qualified health care professional (e.g., nurse practitioner (NP), physician's assistant (PA)) (Note: physician, NP or PA do not have to be present in the room during the session; however, must be immediately available and accessible for medical consultations and emergencies at all times while services are being furnished under the program); and
  • Facility is located in a physician's office, or outpatient hospital setting, and has the necessary cardio-pulmonary, emergency, diagnostic, and therapeutic life-saving equipment immediately available (e.g., cardiopulmonary resuscitation equipment, defibrillator); and
  • An individual out-patient exercise program has been created that can be self-monitored and maintained; and
  • There has been a psychosocial assessment; and
  • Cardiac risk factor modification, including education, counseling and behavioral intervention is tailored to individual needs; and
  • Entails an outcomes assessment (e.g., objective clinical measures of exercise performance).

Aetna considers additional cardiac rehabilitation services medically necessary when the eligible member has an additional qualifying event for any of the following conditions:

  • Another cardiovascular surgery or angioplasty; or
  • Another documented myocardial infarction or extension of initial infarction; or
  • New clinically significant coronary lesions documented by cardiac catheterization.
Note: Up to an additional 36 sessions is considered medically necessary for continuation (not to exceed a total of 72 sessions).

Experimental and Investigational

Cardiac rehabilitation programs are not recommended and are considered experimental and investigational for individuals with coronary artery disease (CAD) who have the following conditions:

  • Acute pericarditis or myocarditis; or
  • Acute systemic illness or fever; or
  • Clinical signs of decompensated aortic stenosis (e.g., angina pectoris and dyspnea on exertion, or syncope); or
  • Forced expiratory volume less than 1 liter; or
  • New-onset atrial fibrillation; or
  • Progressive worsening of exercise tolerance or dyspnea at rest or on exertion over the previous 3 to 5 days; or
  • Recent embolism or thrombophlebitis; or
  • Third-degree heart block without pacemaker; or
  • Uncontrolled diabetes; or
  • Unstable angina.

Aetna considers cardiac rehabilitation experimental and investigational for all other indications including the following (not an all-inclusive list) because of insufficient evidence in the peer-reviewed literature:

  • Atrial fibrillation (other than following the Maze procedure)
  • Following balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension
  • Following repair of sinus venosus atrial septal defect
  • Individuals who are too debilitated to exercise
  • Individuals with lymphoma undergoing autologous hematopoietic stem cell transplantation
  • Postural tachycardia syndrome
  • Secondary prevention after transient ischemic attack or mild, non-disabling stroke
  • Uncompensated heart failure
  • Uncontrolled arrhythmias.

Footnotes* Supervision by a physician or other qualified healthcare professional of cardiac rehabilitation program without continuous electrocardiographic (ECG) monitoring is considered experimental and investigational; clinician supervision of such non-monitored programs has no proven value.

Note: Phase III and Phase IV cardiac rehabilitation programs are not covered under standard Aetna benefit plans as these programs do not require direct supervision by a physician or advanced practitioner (NP or PA), or continuous ECG monitoring. These programs are considered educational and training in nature.  Education and training programs are generally not covered under most Aetna benefit plans.  Please check benefit plan descriptions.

See CPB 0267 - Intensive Cardiac Rehabilitation Programs.

Background

Patients who have cardiovascular events are often functional in society and employed prior to a cardiac event, and frequently require only re-entry into their former life pattern.  Cardiac rehabilitation serves this purpose by providing a supervised program in the outpatient setting that involves medical evaluation, an ECG-monitored physical exercise program, cardiac risk factor modification, education, and counseling.

Cardiac rehabilitation is designed to help individuals with conditions such as heart or vascular disease return to a healthier and more productive life. This includes individuals who have had heart attacks, open heart surgery, stable angina, vascular disease or other cardiac related health problems.

Traditionally, cardiac rehabilitation programs have been classified into 4 phases, phase I to IV, representing a progression from the hospital (phase I) to a medically supervised out-patient program (phases II) to maintenance programs that are structured for community or home-based settings (phase III or IV).  Phase I cardiac rehabilitation begins in the hospital (inpatient) after experiencing a heart attack or other major heart event. During this phase, individuals receive education and nutritional counseling to prepare them for discharge. Phase II outpatient cardiac rehabilitation begins after leaving the hospital. As described by the U.S. Public Health Service, it is a comprehensive, long-term program including medical evaluation, prescribed exercise, cardiac risk factor modification, education and counseling. Phase II refers to medically supervised programs that typically begin one to three weeks after discharge and provide appropriate electrocardiographic (ECG) monitoring. Phase III and phase IV cardiac rehabilitation programs encourage exercise and healthy lifestyle performed at an outpatient medical facility, home or in a fitness center with the goal of continuing the risk factor modification and exercise program learned in phase II. Phase III and IV do not require direct physician supervision or continuous ECG monitoring. These programs encourage a commitment to regular exercise and healthy habits for risk factor modification to establish lifelong cardiovascular fitness. Some programs combine phases III and IV (CMS, 2006).

Cardiac rehabiliation phase II sessions can take place in an outpatient hospital setting or a physician's office (CGS, 2018). Per the Centers for Medicare & Medicaid Services (CMS, 2010) and the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR, 2019), cardiac rehabilitation sessions require direct physician supervision. Although the physician does not have to be present in the room during the CR sessions, all CR settings must have a physician immediately available and accessible for medical consultations and emergencies at all times when items and services are being furnished under the program. This provision is satisfied if the physician meets the requirements for supervision for physician office services, at section 410.26; and for hospital outpatient services at section 410.27. For pulmonary rehabilitation, cardiac rehabilitation, and intensive cardiac rehabilitation services, direct supervision must be furnished by a doctor of medicine or osteopathy, as specified in §§410.47 and 410.49, respectively (CGS, 2018). AACVPR website (2018) also state that for cardiac rehabilitation sessions "the physician does not need to be in the rehab suite but must be immediately available and interruptible".

Due to changes in hospital and health care practices, and the need to accommodate patients at various stages of disease risk, some have argued that the need for phase designation becomes inappropriate, and that cardiac rehabilitation programs can be more appropriately distinguished as inpatient, outpatient or community/home-based programs.  Participation within these programs is determined by appropriate risk stratification in order to maximize health care resources and patient benefit.  Irrespective of the program, there should be regular communication, in the form of progress reports, between the program staff and the patient’s attending physician (Ignaszewski and Lear, 1998).

Entry into such programs is based on the demonstrated limitation of functional capacity on exercise stress testing, and the expectation that medically supervised exercise training will improve functional capacity to a clinically significant degree.  The exercise test in cardiac rehabilitation is a vital component of the overall rehabilitative process as it provides continuous follow-up in a noninvasive manner and adds information to the overall physical evaluation.  In general, testing is performed before entering the cardiac rehabilitation exercise program, and sequentially during the program to provide information on the changes in cardiac status, prognosis, functional capacity, and evidence of training effect.  The central component of cardiac rehabilitation is a prescribed regimen of physical exercises intended to improve functional work capacity and to increase the patient's confidence and well-being.  Depending on the degree of debilitation, cardiac patients may or may not require a full or supervised rehabilitation program.

The scientific literature documents that some of the benefits of participation in a cardiac rehabilitation program include decreased symptoms of angina pectoris, dyspnea, and fatigue, and improvement in exercise tolerance, blood lipid levels, and psychosocial well-being, as well as a reduction in weight, cigarette smoking and stress.  The efficacy of modification of risk factors in reducing the progression of coronary artery disease and future morbidity and mortality has been established.  Meta-analysis of data from random controlled studies indicates a 20 % to 25 % reduction in mortality in patients participating in cardiac rehabilitation following myocardial infarction as compared to controls.

The typical model for delivering outpatient cardiac rehabilitation in the United States is for patients to attend sessions 2 to 3 times per week for up to 12 to 18 weeks (36 total sessions) (CMS, 2006).  A session typically lasts for approximately 1 hour and includes aerobic and/or resistance exercises with continuous electro-cardiographic monitoring.  There are alternative approaches to this typical model.  Patients can be classified as low-, moderate- or high-risk for participating in exercise based on a combination of clinical and functional data.  The number of recommended supervised exercise sessions varies by risk level: low-risk patients receive 6 to 18 exercise sessions over 30 days or less from the date of the cardiac event/procedure; moderate-risk 12 to 24 sessions over 60 days; and high-risk 18 to 36 sessions over 90 days (Hamm, 2008; AACVPR, 2004).

There is limited evidence on the appropriate duration of cardiac rehabilitation.  Hammill et al (2010) stated that for patients with coronary heart disease, exercise-based cardiac rehabilitation improves survival rate and has beneficial effects on risk factors for coronary artery disease.  However, the relationship between the number of sessions attended and long-term outcomes is unknown.  In a national 5 % sample of Medicare beneficiaries, these investigators identified 30,161 elderly patients who attended at least 1 cardiac rehabilitation session between January 1, 2000, and December 31, 2005.  They used a Cox proportional hazards model to estimate the relationship between the number of sessions attended and death and myocardial infarction (MI) at 4 years.  The cumulative number of sessions was a time-dependent co-variate.  After adjustment for demographical characteristics, co-morbid conditions, and subsequent hospitalization, patients who attended 36 sessions had a 14 % lower risk of death (hazard ratio [HR], 0.86; 95 % confidence interval [CI]: 0.77 to 0.97) and a 12 % lower risk of MI (HR, 0.88; 95 % CI: 0.83 to 0.93) than those who attended 24 sessions; a 22 % lower risk of death (HR, 0.78; 95 % CI: 0.71 to 0.87) and a 23 % lower risk of MI (HR, 0.77; 95 % CI: 0.69 to 0.87) than those who attended 12 sessions; and a 47 % lower risk of death (HR, 0.53; 95 % CI: 0.48 to 0.59) and a 31 % lower risk of MI (HR, 0.69; 95 % CI: 0.58 to 0.81) than those who attended 1 session.  The authors concluded that among Medicare beneficiaries, a strong dose-response relationship existed between the number of cardiac rehabilitation sessions and long-term outcomes.  Attending all 36 sessions reimbursed by Medicare was associated with lower risks of death and MI at 4 years compared with attending fewer sessions.

Prior and colleagues (2011) tested feasibility and effectiveness of 6-month outpatient comprehensive cardiac rehabilitation (CCR) for secondary prevention after transient ischemic attack or mild, non-disabling stroke.  Consecutive consenting subjects having sustained a transient ischemic attack or mild, non-disabling stroke within the previous 12 months (mean of 11.5 weeks; event-to-CCR entry) with greater than or equal to 1 vascular risk factor, were recruited from a stroke prevention clinic providing usual care.  These researchers measured 6-month CCR outcomes following a prospective cohort design.  Of 110 subjects recruited from January 2005 to April 2006, 100 subjects (mean age of 64.9 years; 46 women) entered and 80 subjects completed CCR.  These investigators obtained favorable, significant intake-to-exit changes in: aerobic capacity (+31.4 %; p < 0.001), total cholesterol (-0.30 mmol/L; p = 0.008), total cholesterol/high-density lipoprotein (-11.6 %; p < 0.001), triglycerides (-0.27 mmol/L; p = 0.003), waist circumference (-2.44 cm; p < 0.001), body mass index (-0.53 kg/m(2); p = 0.003), and body weight (-1.43 kg; p = 0.001).  Low-density lipoprotein (-0.24 mmol/L), high-density lipoprotein (+0.06 mmol/L), systolic (-3.21 mm Hg) and diastolic (-2.34 mm Hg) blood pressure changed favorably, but non-significantly.  A significant shift toward non-smoking occurred (p = 0.008).  Compared with intake, 11 more individuals (25.6 % increase) finished CCR in the lowest-mortality risk category of the Duke Treadmill Score (p < 0.001).  The authors concluded that CCR is feasible and effective for secondary prevention after transient ischemic attack or mild, non-disabling stroke, offering a promising model for vascular protection across chronic disease entities.  The authors stated that they know of no similar previous investigation, and are now conducting a randomized trial.

Pack et al (2013) noted that outpatient CR decreases mortality rates but is under-utilized.  Current median time from hospital discharge to enrollment is 35 days.  These researchers hypothesized that an appointment within 10 days would improve attendance at CR orientation.  At hospital discharge, 148 patients with a non-surgical qualifying diagnosis for CR were randomized to receive a CR orientation appointment either within 10 days (early) or at 35 days (standard).  The primary end-point was attendance at CR orientation. Secondary outcome measures were attendance at greater than or equal to 1 exercise session, the total number of exercise sessions attended, completion of CR, and change in exercise training work-load while in CR.  Average age was 60 ± 12 years; 56 % of participants were male and 49 % were black, with balanced baseline characteristics between groups.  Median time (95 % CI) to orientation was 8.5 (7 to 13) versus 42 (35 to NA [not applicable]) days for the early and standard appointment groups, respectively (p < 0.001).  Attendance rates at the orientation session were 77 % (57/74) versus 59%  (44/74) in the early and standard appointment groups, respectively, which demonstrated a significant 18 % absolute and 56 % relative improvement (relative risk, 1.56; 95 % CI: 1.03 to 2.37; p = 0.022).  The number needed to treat was 5.7.  There was no difference (p > 0.05) in any of the secondary outcome measures, but statistical power for these end points was low.  Safety analysis demonstrated no difference between groups in CR-related adverse events.  The authors concluded that early appointments for CR significantly improved attendance at orientation.  This simple technique could potentially increase initial CR participation nationwide.

In a retrospective cohort study, Beauchamp et al (2013) examined if attendance at CR independently predicts all-cause mortality over 14 years and whether there is a dose-response relationship between the proportion of CR sessions attended and long-term mortality.  The sample comprised 544 men and women eligible for CR following MI, coronary artery bypass surgery or percutaneous interventions.  Participants were tracked 4 months after hospital discharge to ascertain CR attendance status.  Main outcome measure was all-cause mortality at 14 years ascertained through linkage to the Australian National Death Index.  In total, 281 (52 %) men and women attended at least 1 CR session.  There were few significant differences between non-attenders and attenders.  After adjustment for age, sex, diagnosis, employment, diabetes and family history, the mortality risk for non-attenders was 58 % greater than for attenders (HR = 1.58, 95 % CI: 1.16 to 2.15).  Participants who attended less than 25 % of sessions had a mortality risk more than twice that of participants attending greater than or equal to 75 % of sessions (odds ratio [OR] = 2.57, 95 % CI: 1.04 to 6.38).  This association was attenuated after adjusting for current smoking (OR = 2.06, 95 % CI: 0.80 to 5.29).  The authors concluded that this study provided further evidence for the long-term benefits of CR in a contemporary, heterogeneous population.  While a dose-response relationship may exist between the number of sessions attended and long-term mortality, this relationship does not occur independently of smoking differences.  They stated that CR practitioners should encourage smokers to attend CR and provide support for smoking cessation.

The Centers for Medicare & Medicaid Services (CMS, 2010) state that cardiac rehabilitation (CR) programs must include a medical evaluation, a program to modify cardiac risk factors, with prescribed exercise, education and counseling. CMS allows for physicians to determine the time period over with CR services are provided as long as it falls within the covered time period identified in the CMS regulation. The regulation allows for coverage of up to 36 1-hour sessions over up to 36 weeks.

In 2014, CMS determined that the evidence was sufficient to expand coverage for cardiac rehabilitation services to beneficiaries with stable, chronic heart failure defined as patients with left ventricular ejection fraction of 35 % or less and New York Heart Association (NYHA) class II to IV symptoms despite being on optimal heart failure therapy for at least 6 weeks. Stable patients are defined as patients who have not had recent (less than or equal to 6 weeks) or planned (less than or equal to 6 months) major cardiovascular hospitalizations or procedures. Per CMS, CR sessions are limted to a maximum of two 1-hour session per day for up to 36 sessions over a period of 36 weeks. Furthermore, and additional 36 sessions may be warranted and approved by the Medicare contractor under section 1862(a)(1)(A) of the Social Security Act (CMS, 2014).

Shibata et al (2012) stated that recent studies have suggested the presence of cardiac atrophy as a key component of the pathogenesis of the postural orthostatic tachycardia syndrome (POTS), similar to physical deconditioning.  It has also been shown that exercise intolerance is associated with a reduced stroke volume (SV) in POTS, and that the high heart rate observed at rest and during exercise in these patients is due to this low SV.  These researchers tested the hypotheses that
  1. circulatory control during exercise is normal in POTS; and
  2. that physical “reconditioning” with exercise training improves exercise performance in patients with POTS.


A total of 19 (18 women) POTS patients completed a 3 month training program.  Cardiovascular responses during maximal exercise testing were assessed in the upright position before and after training.  Resting left ventricular diastolic function was evaluated by Doppler echocardiography.  Results were compared with those of 10 well-matched healthy sedentary controls.  A lower SV resulted in a higher heart rate in POTS at any given oxygen uptake (V(O(2))) during exercise while the cardiac output (Q(c))-V(O(2)) relationship was normal.  V(O(2peak)) was lower in POTS than controls (26.1 ± 1.0 (SEM) versus 36.3 ± 0.9 ml kg-1 min-1; p < 0.001) due to a lower peak SV (65 ± 3 versus 80 ± 5 ml; p = 0.009).  V(O(2peak)) increased by 11 % (p < 0.001) due to increased peak SV (p = 0.021) and was proportional to total blood volume.  Peak heart rate was similar, but heart rate recovery from exercise was faster after training than before training (p = 0.036 for training and 0.009 for interaction).  Resting diastolic function was mostly normal in POTS before training, though diastolic suction was impaired (p = 0.023).  There were no changes in any Doppler index after training.  The authors concluded that these results suggested that short-term exercise training improves physical fitness and cardiovascular responses during exercise in patients with POTS. 

Benarroch (2012) noted that management of POTS includes avoidance of precipitating factors, volume expansion, physical counter-maneuvers, exercise training, pharmacotherapy (fludrocortisone, midodrine, beta-blockers, and/or pyridostigmine), and behavioral-cognitive therapy.

Although it can be argued that a structured exercise program for physical reconditioning may be beneficial for patients with POTS, it is unclear there is a need for a supervised cardiac rehabilitation program.  Furthermore, an UpToDate review on “Postural tachycardia syndrome” (Freeman and Kaufman, 2014) does not mention cardiac rehabilitation as a management tool.

Gaalema et al (2015) noted that continued smoking after a cardiac event greatly increases mortality risk.  Smoking cessation and participation in CR are effective in reducing morbidity and mortality.  However, these 2 behaviors may interact; those who smoke may be less likely to access or complete CR.  These researchers explored the association between smoking status and CR referral, attendance, and adherence.  They carried out a systematic literature search examining associations between smoking status and CR referral, attendance and completion in peer-reviewed studies published through July 1, 2014.  For inclusion, studies had to report data on outpatient CR referral, attendance or completion rates and smoking status had to be considered as a variable associated with these outcomes.  A total of 56 studies met inclusion criteria.  A history of smoking was associated with an increased likelihood of referral to CR.  However, smoking status also predicted not attending CR and was a strong predictor of CR drop-out.  The authors concluded that continued smoking after a cardiac event predicts lack of attendance in, and completion of CR.  The issue of smoking following a coronary event deserves renewed attention.

Huang et al (2015) examined the effectiveness of telehealth intervention-delivered CR compared with center-based supervised CR.  Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library and the Chinese BioMedical Literature Database (CBM), were searched to April 2014, without language restriction.  Existing randomized controlled trials (RCTs), reviews, relevant conference lists and gray literature were checked.  Randomized controlled trials that compared telehealth intervention delivered CR with traditional center-based supervised CR in adults with coronary artery disease (CAD) were included.  Two reviewers selected studies and extracted data independently.  Main clinical outcomes including clinical events, modifiable risk factors or other end-points were measured.  A total of 15 articles reporting 9 trials were reviewed, most of which recruited patients with MI or re-vascularization.  No statistically significant difference was found between telehealth interventions delivered and center-based supervised CR in exercise capacity (standardized mean difference (SMD) -0.01; 95 % CI: -0.12 to 0.10), weight (SMD -0.13; 95 % CI: -0.30 to 0.05), systolic and diastolic blood pressure (SBP and DBP) (mean difference (MD) -1.27; 95 % CI: -3.67 to 1.13 and MD 1.00; 95 % CI: -0.42 to 2.43, respectively), lipid profile, smoking (risk ratio (RR) 1.03; 95 % CI: 0.78 to 1.38), mortality (RR 1.15; 95 % CI: 0.61 to 2.19), quality of life and psychosocial state.  The authors concluded that telehealth intervention-delivered CR does not have significantly inferior outcomes compared to center-based supervised program in low-to-moderate risk CAD patients.  Telehealth intervention offers an alternative deliver model of CR for individuals less able to access center-based CR.  Choices should reflect preferences, anticipation, risk profile, funding, and accessibility to health service.

In a Cochrane review, Taylor et al (2015) compared the effect of home-based and supervised center-based CR on mortality and morbidity, health-related quality of life, and modifiable cardiac risk factors in patients with heart disease.  To update searches from the previous Cochrane review, these investigators searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 9, 2014), MEDLINE (Ovid, 1946 to Week 1 of October, 2014), EMBASE (Ovid, 1980 to Week 41 of 2014), PsycINFO (Ovid,  to Week 2 of October, 2014), and CINAHL (EBSCO, to October 2014).  They checked reference lists of included trials and recent systematic reviews.  No language restrictions were applied.  The authors concluded that this updated review supports the conclusions of the previous version of this review that home- and center-based forms of CR seem to be equally effective for improving the clinical and health-related quality of life outcomes in low risk patients after MI or re-vascularization, or with heart failure (HF).  This finding, together with the absence of evidence of important differences in healthcare costs between the 2 approaches, supports the continued expansion of evidence-based, home-based CR programs.  The choice of participating in a more traditional and supervised center-based program or a home-based program should reflect the preference of the individual patient.  They stated that further data are needed to determine whether the effects of home- and center-based CR reported in these short-term trials can be confirmed in the longer term.  A number of studies failed to give sufficient detail to assess their risk of bias.

Acute Coronary Syndrome

Rauch and colleagues (2016) noted that the prognostic effect of multi-component CR in the modern era of statins and acute re-vascularization remains controversial.  These investigators evaluated the effect of CR on total mortality and other clinical end-points after an acute coronary event.  Randomized controlled trials, retrospective controlled cohort studies (rCCSs) and prospective controlled cohort studies (pCCSs) evaluating patients after acute coronary syndrome (ACS), coronary artery bypass grafting (CABG) or mixed populations with CAD were included, provided the index event was in 1995 or later.  Out of 18,534 abstracts, 25 studies were identified for final evaluation (RCT: n = 1; pCCS: n = 7; rCCS: n = 17), including n = 219,702 patients (after ACS: n = 46,338; after CABG: n = 14,583; mixed populations: n = 158,781; mean follow-up of 40 months).  Heterogeneity in design, biometrical assessment of results and potential confounders was evident; CCSs evaluating ACS patients showed a significantly reduced mortality for CR participants (pCCS: HR 0.37, 95 % CI: 0.20 to 0.69; rCCS: HR 0.64, 95 % CI: 0.49 to 0.84; OR 0.20, 95 % CI: 0.08 to 0.48), but the single RCT fulfilling Cardiac Rehabilitation Outcome Study (CROS) inclusion criteria showed neutral results.  These investigators noted that CR participation was also associated with reduced mortality after CABG (rCCS: HR 0.62, 95 % CI: 0.54 to 0.70) and in mixed CAD populations.  The authors concluded that CR participation after ACS and CABG was associated with reduced mortality even in the modern era of CAD treatment.  However, the heterogeneity of study designs and CR programs highlighted the need for defining internationally accepted standards in CR delivery and scientific evaluation.

Atrial Fibrillation

In a Cochrane review, Risom and colleagues (2017) evaluated the benefits and harms of exercise-based CR programs, alone or with another intervention, compared with no-exercise training controls in adults who currently have atrial fibrillation (AF), or have been treated for AF.  These investigators searched the following electronic databases; CENTRAL and the Database of Abstracts of Reviews of Effectiveness (DARE) in the Cochrane Library, Medline Ovid, Embase Ovid, PsycINFO Ovid, Web of Science Core Collection Thomson Reuters, CINAHL EBSCO, LILACS Bireme, and 3 clinical trial registers on July 14, 2016.  They also checked the bibliographies of relevant systematic reviews identified by the searches.  They imposed no language restrictions.  These researchers included RCTs that examined exercise-based interventions compared with any type of no-exercise control.  They included trials with adults aged 18 years or older with AF, or post-treatment for AF.  Two authors independently extracted data.  They assessed the risk of bias using the domains outlined in the Cochrane Handbook for Systematic Reviews of Interventions.  They assessed clinical and statistical heterogeneity by visual inspection of the forest plots, and by using standard Chi² and I² statistics.  These researchers performed meta-analyses using fixed-effect and random-effects models; they used SMDs where different scales were used for the same outcome.  They assessed the risk of random errors with trial sequential analysis (TSA) and used the GRADE methodology to rate the quality of evidence, reporting it in the “Summary of findings” table.  A total of 6 RCTs with 421 patients with various types of AF were included in this review.  All trials were conducted between 2006 and 2016, and had short follow-up (8 weeks to 6 months).  Risks of bias ranged from high risk to low risk.  The exercise-based CR programs in 4 trials consisted of both aerobic exercise and resistance training, in 1 trial consisted of Qi-gong (slow and graceful movements), and in another trial, consisted of inspiratory muscle training.  For mortality, very low-quality evidence from 6 trials suggested no clear difference in deaths between the exercise and no-exercise groups (RR 1.00, 95 % CI: 0.06 to 15.78; participants = 421; I² = 0 %; deaths = 2).  Very low-quality evidence from 5 trials suggested no clear difference between groups for serious adverse events (AEs) (RR 1.01, 95 % CI: 0.98 to 1.05; participants = 381; I² = 0 %; events = 8).  Low-quality evidence from 2 trials suggested no clear difference in health-related quality of life (QOL) for the Short Form-36 (SF-36) physical component summary measure (MD 1.96, 95 % CI: -2.50 to 6.42; participants = 224; I² = 69 %), or the SF-36 mental component summary measure (MD 1.99, 95 % CI: -0.48 to 4.46; participants = 224; I² = 0 %).  Exercise capacity was assessed by cumulated work, or maximal power (Watt), obtained by cycle ergometer, or by 6-minute walking test (6MWT), or ergo-spirometry testing measuring VO2 peak.  These researchers found moderate-quality evidence from 2 studies that exercise-based CR increased exercise capacity, measured by VO2 peak, more than no exercise (MD 3.76, 95 % CI: 1.37 to 6.15; participants = 208; I² = 0 %); and very low-quality evidence from 4 studies that exercise-based rehabilitation increased exercise capacity more than no exercise, measured by the 6MWT (MD 75.76, 95 % CI: 14.00 to 137.53; participants = 272; I² = 85 %).  When these investigators combined the different assessment tools for exercise capacity, they found very low-quality evidence from 6 trials that exercise-based rehabilitation increased exercise capacity more than no exercise (SMD 0.86, 95 % CI: 0.46 to 1.26; participants = 359; I² = 65 %).  Overall, the quality of the evidence for the outcomes ranged from moderate to very-low.  The authors concluded that due to few randomized patients and outcomes, they could not evaluate the real impact of exercise-based CR on mortality or serious AEs.  The evidence showed no clinically relevant effect on health-related QOL.  Pooled data showed a positive effect on the surrogate outcome of physical exercise capacity, but due to the low number of patients and the moderate to very low-quality of the underpinning evidence, the authors could not be certain of the magnitude of the effect.  Moreover, they stated that future high-quality randomized trials are needed to evaluate the benefits and harms of exercise-based CR for adults with AF on patient-relevant outcomes.

Following Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension

Fukui and co-workers (2016) determined the safety and effectiveness of CR initiated immediately following balloon pulmonary angioplasty (BPA) in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) who presented with continuing exercise intolerance and symptoms on effort even after a course of BPA; 2 to 8 sessions/patient.  A total of 41 consecutive patients with inoperable CTEPH who underwent their final BPA with improved resting mean pulmonary arterial pressure (PAP) of 24.7±5.5 mm Hg and who suffered remaining exercise intolerance were prospectively studied.  Participants were divided into 2 groups just after the final BPA (6.8 ± 2.3 days): (i) patients with (CR group, n = 17) or without (non-CR group, n = 24) participation in a 12-week CR of 1-week in-hospital training followed by an 11-week out-patient program.  Cardiopulmonary exercise testing (CPET), hemodynamics, and quality of life (QOL) were assessed before and after CR.  No significant between-group differences were found for any baseline characteristics.  At week 12, peak oxygen uptake (VO2), per cent predicted peak VO2 (70.7 ± 9.4 % to 78.2 ± 12.8 %, p < 0.01), peak work-load, and oxygen pulse significantly improved in the CR group compared with the non-CR group, with a tendency towards improvement in mental health-related QOL.  Quadriceps strength and heart failure (HF) symptoms (WHO functional class, 2.2 to 1.8, p = 0.01) significantly improved within the CR group.  During the CR, no patient experienced adverse events (AEs) or deterioration of right-sided HF or hemodynamics as confirmed via right heart catheterization.  The authors concluded that the combination of BPAs and subsequent CR for inoperable CTEPH additively ameliorated exercise intolerance to near-normal levels and improved HF symptoms, with a tendency towards improvement in mental health-related QOL.  They stated that this promising new treatment strategy did not require a prolonged hospital stay for initial in-hospital training and did not lower patient compliance; however, further large, randomized, multi-center studies are needed to confirm the present findings.

The authors stated that this study had several drawbacks:
  1. it lacked randomization during group assignment, although it was prospectively designed with a control group.  Thus, they could not exclude the possibility that selection bias affected the present results.  However, no significant between-group differences were found in any baseline characteristics, which might strengthen the value of the present results,
  2. this study was implemented in a single center, although the center is one of the largest pulmonary hypertension centers in Japan with experienced rehabilitation centers.  These results should be confirmed in a large, randomized, multi-center study,
  3. the increase in 6-minute walk distance (6MWD) in the CR group did not reach statistical significance -- this was inconsistent with previous studies with patients with CTEPH. 

It was possible that these patients with CR walked much better in the baseline 6MWD examination (498 ± 96 m) than the patients with CTEPH in previous studies (353 to 453 m), because these patients had already undergone BPAs before group assignment, in addition to PH-specific therapies.  This was also supported by the findings that exercise training might be more effective in patients with a lower 6MWD, rather than those who have a near-normal 6MWD (greater than 550 m) and that 6MWD was less sensitive to increases in peak VO2 at distances greater than 500 m, (iv) VO2 at anaerobic threshold (AT) did not significantly improve after CR, consistent with the findings of Yuan et al who conducted a systematic review and meta-analysis on exercise training for PH.  In addition, these researchers could not accurately determine the AT level in the pre-interventional and/or post-interventional CPET in 5 of 17 patients in the CR group due to ventilatory oscillation-like changes or increased ventilatory drives even at rest, implying that the AT level was unreliable in this population, and (v) physical-related QOL scores were unchanged after CR, which was inconsistent with previous studies.  The authors could explain this discrepancy by their preliminary data that physical-related QOL scores in their patients had already improved to a certain degree before CR via BPA alone (data not shown), as well as hemodynamics and functional capacity.

Following Heart Valve Surgery

Sibilitz and colleagues (2016) stated that the evidence for CR after valve surgery remains sparse.  Thus, current recommendations are based on patients with ischemic heart disease.  In a randomized clinical trial, these researchers examined the effects of CR versus usual care after heart valve surgery.  The trial was an investigator-initiated, randomized superiority trial (The CopenHeartVR trial, VR; valve replacement or repair).  They randomized 147 patients after heart valve surgery 1:1 to 12 weeks of CR consisting of physical exercise and monthly psycho-educational consultations (intervention) versus usual care without structured physical exercise or psycho-educational consultations (control).  Primary outcome was physical capacity measured by VO2 peak and secondary outcome was self-reported mental health measured by Short Form-36.  A total of 76 % of participants were men, mean age of 62 years, with aortic (62 %), mitral (36 %) or tricuspid/pulmonary valve surgery (2 %).  Cardiac rehabilitation compared with control had a beneficial effect on VO2 peak at 4 months (24.8 mL/kg/min versus 22.5 mL/kg/min, p = 0.045); but did not affect Short Form-36 Mental Component Scale at 6 months (53.7 versus 55.2 points, p = 0.40) or the exploratory physical and mental outcomes.  Cardiac rehabilitation increased the occurrence of self-reported non-serious AEs (11/72 versus 3/75, p = 0.02).  The authors concluded that CR following heart valve surgery significantly improved VO2 peak at 4 months but had no effect on mental health and other measures of exercise capacity and self-reported outcomes.  Moreover, they stated that further research is needed to justify CR in this patient group.

Following Repair of Sinus Venosus Atrial Septal Defects

A Medscape review on “Sinus venosus atrial septal defects” (Satou, 2015) did not mention CR.  Furthermore, an UpToDate review on “Surgical and percutaneous closure of atrial septal defects in adults” (Connolly, 2017) does not mention CR as a management tool.

Cardiac Rehabilitation Following Septal Myectomy

Septal myectomy is one treatment option that is perfomed surgically via open-heart in order to reduce the muscle thickening that occurs in symptomatic patients with hypertrophic cardiomyopathy (HCM) refractory to medications, or with left ventricular outlow tract (LVOT) obstruction severely restricting blood ejection from the heart. Surgical spetal myectomy relieves LVOT obstruction by directly removing the thickened septal wall. The surgical septal myectomy involves performing a thoractomy, with individual being placed on cardiopulmonary bypass. Surgical septal myectomy results in resolution of the LVOT gradient and improvmeent in heart failure symptoms in most individuals. Long-term outcomes also includes reductions in implantable cardioverter-defibrillator (ICD) discharges and improvment in left atrial volumes and pulmonary hypertension (Maron, 2019).

Redwood et al (1979) noted that the effect of left ventriculomyotomy and myectomy on exercise capacity and cardiac function in patients with obstructive hypertrophic cardiomyopathy has not previously been determined.  In this study, a total of 29 patients were evaluated during graded treadmill exercise before and after operation.  Post-operatively, 27 of 29 patients reported symptomatic improvement and had greatly reduced left ventricular outflow gradient; 25 of 28 patients (89 %) attained higher exercise levels after operation, and this was accompanied by an increase in total body oxygen consumption from 16 to 21 ml/min per kg (p < 0.005).  A significant increase in cardiac index during maximal exercise also accompanied this improved exercise performance (5.0 to 5.7 L/min/m2, p < 0.05).  The increase in maximal cardiac index was associated with greater desaturation of mixed venous blood (34 to 24 %, p < 0.02) in patients with pre-operative angina.  At a given level of mixed venous oxygen saturation (30 %), overall mean cardiac index was higher post-operatively (4.6 to 5.2 L/min/m2, p < 0.05).  The authors concluded that these findings suggested that, although several mechanisms probably contributed to symptomatic improvement after myotomy and myectomy, enhanced cardiac performance played an important role in the majority of patients.

Franz et al (2008) stated that infective endocarditis due to viridans streptococci is associated with a mortality of 5 to 10 %.  Even today, it remains difficult to diagnose it at an early stage, to select a sufficient antibiotic therapy and to choose the right time for surgical intervention.  These investigators reported on the case of a 37-year old man who presented with anemia, fever, adynamia and a loud systolic murmur over the base of the heart.  Blood culture data were positive for Streptococcus mitis.  Trans-thoracic echocardiography (TTE) revealed an endocarditis of the aortic and mitral valve with regurgitations as well as a hypertrophic obstructive cardiomyopathy.  The hemodynamically stable patient was treated with penicillin G, gentamicin and verapamil.  Because of an extension of valve vegetations and a decline in the hemodynamic situation with an incipient sepsis, the patient was surgically treated urgently by replacement of the aortic and mitral valve as well as a Morrow septal myectomy.  A post-operative sepsis required the application of high catecholamine doses.  Because of a respiratory insufficiency, a prolonged mechanical ventilation was required.  Finally, the patient could be discharged for in-hospital rehabilitation.  The authors concluded that the indication for surgical therapy in patients with endocarditis of the aortic and mitral valve as well as hypertrophic obstructive cardiomyopathy should be critically discussed with regard to the patient's age, the aims of conservative therapy, and the consequences of a surgical intervention.  If there were any indices of a disease progress in spite of antibiotic therapy, patients should be subjected to cardiac surgery immediately.

Although there is insuffient evidence via randomized controlled clinical trials to support cardiac rehabilitation specifically for surgical septal myectomy, cardiac rehabilitation programs' efficacy has been established in other open-heart surgical indications (e.g. CABG, heart transplant).

Individuals With Lymphoma Undergoing Autologous Hematopoietic Stem Cell Transplantation

Rothe and colleagues (2018) noted that worldwide more than 50,000 hematopoietic stem cell transplants (HSCTs) are performed annually; and HSCT patients receive multiple cardiotoxic therapies (chemotherapy and radiation therapy) in addition to severe physical deconditioning during hospital admission.  These researchers hypothesized that guided exercise in a CR program following autologous HSCT is a safe and feasible intervention.  This was a pilot project to assess for safety, feasibility and impact of 8 weeks of CR in HSCT patients following transplant.  Consecutive patients with lymphoma underwent standard activity protocol testing before HSCT, at 6 weeks following HSCT (prior to CR), and at 14 weeks following HSCT (at completion of CR), consisting of grip strength (GS), gait speed (GtS), timed up-and-go (TUG), and 6-minute walk test (6MWT); CR consisted of 8 weekly visits for guided exercise.  Activity tolerance protocol data of 30 patients (24 male, 6 female) from December 2014 to December 2016 were analyzed using repeated measures (analysis of variance [ANOVA]) to observe for changes in GS, GtS, TUG, and 6MWT.  Statistically significant improvements were found in GS (p < 0.005), GtS (p = 0.02), and 6MWT (p = 0.001).  These improvements showed that guided CR-based exercise may assist HSCT survivors to meet or even surpass baseline exercise levels and improve physical functioning.  There were no AEs (i.e., death or injury) during the study period; 57 % of referred patients participated in CR, exceeding documented CR adherence in cardiac populations.  The authors concluded that the addition of CR-based exercise programming in HSCT survivorship care of patients with lymphoma was a safe and feasible intervention to assist in recovery following transplant.  These preliminary findings need to be validated by well-designed studies.

Symptomatic Individuals with Non-Obstructive Coronary Artery Disease

Kissel and colleagues (2018) stated that non-obstructive coronary artery disease (NOCAD) on coronary angiography is a common finding in patients with stable angina.  Angina in NOCAD patients is thought to be caused by endothelial dysfunction of the epicardial coronary arteries and/or the microvasculature.  Treatment is empiric, and 30 % of patients remain symptomatic in spite of therapy.  It is well known that physical exercise can improve endothelial function.  These investigators evaluated the evidence on effects of physical exercise in NOCAD patients with angina.  They performed a literature search (up to March 13, 2018) using the following search terms: syndrome X, microvascular angina, non-obstructive coronary artery disease and exercise training, cardiac rehabilitation, endothelial function.  All original publications which examined the effect of a CR program or exercise training (ET) on patients with angina and NOCAD.  A total of 8 studies, of which 4 were RCTs, examined 218 participants, 162 in an intervention and 56 in control groups.  Most patients were women (97.7 %).  Exercise programs varied from 8 weeks to 4 months at moderate intensity and some included relaxation therapy.  The studies examined the effect of CR on exercise capacity, QOL, and perfusion defects.  CR increased exercise capacity, oxygen uptake, symptom severity, and QOL; myocardial perfusion improved.  The authors concluded that CR appeared to be beneficial in symptomatic patients with NOCAD, improving exercise capacity and QOL and reducing severity of symptoms and myocardial perfusion defects.  Moreover, these researchers stated that data were limited to a small number of predominantly female patients.  They stated that further larger trials with inclusion of men are needed to determine the optimal rehabilitation protocols and define its long-term benefits.

The authors stated that this study had several drawbacks.  First, the included studies were all small with low patient numbers in each treatment group, thus limiting statistical power.  In addition, not all of the studies were randomized.  Second, the majority of studies included only women (97.7 %).  Although cardiac syndrome X is more common in women, it is well established that it also occurs in men, with up to 30 % of men with SA presenting for coronary angiogram, have NOCAD.  Given that the studies were limited to women, these investigators could only speculate whether ET has the same positive effect in men.  Outcome measures in the reported trials consisted mostly of parameters for exercise capacity, easily measurable physical values, and QOL assessed by questionnaires.  All outcomes were evaluated in the short-term, directly after completion of the CR program.  No data were available on the long-term effects of CR programs in NOCAD, and whether the beneficial effect was sustained over time.  Furthermore, it would be interesting to find out whether this transferred into hard end-points like less frequent hospitalization, lower treatment costs, and possibly an improved outcome.  For a long time, symptomatic patients with NOCAD were assured of the benign nature of their condition.  However, recent data pointed towards an adverse outcome of these patients in regard to MI, cardiovascular, and all-cause mortality.  Thus, it would be intriguing to examine if CR also led to an improved cardiovascular outcome in this patient population.  These researchers stated that current studies on the effect of ET in symptomatic patients with NOCAD are promising but larger, randomized studies with inclusion of men are needed to evaluate the benefit of ET on hard end-points and the long-term effect of ET.  Furthermore, a study protocol should include randomized groups to determine the optimal training protocol in regard to training intensity, duration, and inclusion of relaxation techniques.  Furthermore, it would be of interest to include vascular function studies to gain further insight into the pathophysiological mechanisms.

Appendix

New York Heart Association (NYHA) Functional Classification System – Designed to classify heart failure according to severity of symptoms:

  • Class I (mild) – No limitations on physical activity; ordinary physical activity does not cause undue fatigue, palpitation, dyspnea (shortness of breath) or anginal pain.
  • Class II (mild) – Slight limitation of physical activity; comfortable at rest; ordinary physical activity results in fatigue, palpitation, dyspnea or anginal pain.
  • Class III (moderate) – Marked limitation of physical activity; comfortable at rest; less than ordinary activity causes fatigue, palpitation, dyspnea or anginal pain.
  • Class IV (severe) – Inability to carry on any physical activity without discomfort; symptoms of cardiac insufficiency may be present even at rest. If any physical activity is undertaken, discomfort increases.

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

CPT codes covered if selection criteria are met:

93798 Physician or other qualified health care professional services for outpatient cardiac rehabilitation; with continuous ECG monitoring (per session) [not covered for Phase III or Phase IV]

CPT codes not covered for indications listed in the CPB:

92997 Percutaneous transluminal pulmonary artery balloon angioplasty; single vessel.
92998 Percutaneous transluminal pulmonary artery balloon angioplasty; each additional vessel
93797 Physician or other qualified health care professional services for outpatient cardiac rehabilitation; without continuous ECG monitoring (per session)

Other CPT codes related to the CPB:

93015- 93024 Cardiovascular stress test using maximal or submaximal treadmill or bicycle exercise, continuous electrocardiographic monitoring, and/or pharmacological stress; with physician supervision, with interpretation and report, or physician supervision only, without interpretation and report, or tracing only, without interpretation and report, or interpretation and report only

HCPCS codes covered if selection criteria are met:

G0422 Intensive cardiac rehabilitation; with or without continuous ECG monitoring with exercise, per session [Ornish Cardiac Rehab Program] [not covered for Phase III or Phase IV]
G0423 Intensive cardiac rehabilitation; with or without continuous ECG monitoring; without exercise, per session [not covered for Phase III or Phase IV]
S9472 Cardiac rehabilitation program, non-physician provider, per diem [not covered for Phase III or Phase IV]

Other HCPCS codes related to the CPB:

S9449 Weight management classes, non-physician provider, per session
S9451 Exercise classes, non-physician provider, per session
S9452 Nutrition classes, non-physician provider, per session
S9453 Smoking cessation classes, non-physician provider, per session
S9454 Stress management classes, non-physician provider, per session
S9470 Nutritional counseling, dietitian visit

ICD-10 codes covered if selection criteria are met:

I02.0 Rheumatic chorea with heart involvement
I05.0 - I05.9, I06.1 - I08.9 Rheumatic mitral, aortic, tricuspid, and multiple valve diseases
I09.81 Rheumatic heart failure (congestive)
I11.0 Hypertensive heart disease with heart failure
I13.0 Hypertensive heart and chronic kidney disease with heart failure and stage 1 through stage 4, chronic kidney disease, or unspecified chronic kidney disease
I13.2 Hypertensive heart and chronic kidney disease with heart failure and stage 5 chronic kidney disease or end stage renal disease
I20.9 Angina pectoris, unspecified [stable]
I21.01 - I25.9 Ischemic heart disease
I21.A1 Myocardial infarction type 2
I21.A9 Other myocardial infarction type
I34.0 - I34.9, I36.0 - I37.9 Nonrheumatic mitral, tricuspid and pulmonary valve disorders
I42.2 Other hypertrophic cardiomyopathy [asymmetric septal hypertrophy]
I42.3 - I42.7 Cardiomyopathy
I46.2 - I46.9 Cardiac arrest
I47.2 Ventricular tachycardia
I47.9 Paroxysmal tachycardia, unspecified
I49.01 Ventricular fibrillation
I49.02 Ventricular flutter
I50.1 - I50.9 Heart failure [compensated or stable]
I97.0, I97.110, I97.130, I97.190 Postprocedural cardiac functional disturbances
Z51.89 Encounter for other specified aftercare
Z94.1 Heart transplant status
Z94.2 Lung transplant status
Z95.1 Presence of aortocoronary bypass graft
Z95.2 Presence of prosthetic heart valve
Z95.3 Presence of xenogenic heart valve
Z95.4 Presence of other heart-valve replacement
Z95.5 Presence of coronary angioplasty implant and graft
Z95.811 Presence of heart assist device
Z95.812 Presence of fully implantable artificial heart
Z98.61 Coronary angioplasty status
Z98.890 Other specified postprocedural status [surgery to heart and great vessels]

ICD-10 codes not covered for indications listed in the CPB (not all-inclusive):

E08.00 - E13.9 Diabetes [uncontrolled]
I06.0 Rheumatic aortic stenosis [moderate to severe]
I20.0 Unstable angina
I27.24 Chronic thromboembolic pulmonary hypertension
I30.0 - I30.9 Acute pericarditis
I35.0 - I35.9 Nonrheumatic aortic valve disorder [moderate to severe stenosis]
I40.1 - I40.9 Acute myocarditis
I44.2 Atrioventricular block, complete [without pacemaker]
I48.0 - I48.2, I48.91 Atrial fibrillation [new onset]
I49.8 Other specified cardiac arrhythmias [postural tachycardia syndrome]
I74.01 - I74.9 Arterial embolism and thrombosis [recent]
I80.0 - I80.9 Phlebitis and thrombophlebitis [recent]
Q21.1 Atrial septal defect [sinus venosus atrial septal defect]
Q23.0 Congenital stenosis of aortic valve [moderate to severe]
Q23.3 Supravalvular aortic stenosis [moderate to severe]
R00.0 Tachycardia [postural]
R06.00 - R06.09 Dyspnea [progressive worsening at rest or on exertion over the previous three to five days]
R06.89 Other abnormalities of breathing [forced expiratory volume of less than one liter]
R50.81 Fever presenting with conditions classified elsewhere [systemic]
R50.9 Fever, unspecified [systemic]
Z86.73 Personal history of transient ischemic attack [TIA], and cerebral infarction without residual deficits [not covered when used to report secondary prevention after transient ischemic attack or mild, non-disabling stroke]

The above policy is based on the following references:

  1. Dinnes J, Kleijnen J, Leitner M, et al. Cardiac rehabilitation. Qual Health Care. 1999;8(1):65-71. 
  2. Thompson DR, De Bono DP. How valuable is cardiac rehabilitation and who should get it? Heart. 1999;82(5):545-546. 
  3. Kobashigawa JA. Postoperative management following heart transplantation. Transplant Proc. 1999;31(5):2038-2046. 
  4. Ades PA, Savage PD, Poehlman ET, et al. Lipid lowering in the cardiac rehabilitation setting. J Cardiopulm Rehabil. 1999;19(4):255-260. 
  5. Ceci V, Chieffo C, Giannuzzi P, et al. Standards and guidelines for cardiac rehabilitation. Working Group on Cardiac Rehabilitation of the European Society for Cardiology. Cardiologia. 1999;44(6):579-584. 
  6. Lavie CJ, Milani RV. Effects of cardiac rehabilitation and exercise training on peak aerobic capacity and work efficiency in obese patients with coronary artery disease. Am J Cardiol. 1999;83(10):1480-1483, A7. 
  7. Paul-Labrador M, Vongvanich P, Merz CN. Risk stratification for exercise training in cardiac patients: Do the proposed guidelines work? J Cardiopulm Rehabil. 1999;19(2):118-125. 
  8. Blackwood R. Cardiac rehabilitation. Curr Opin Cardiol. 1990;5(4):502-507. 
  9. Kobashigawa JA, Leaf DA, Lee N, et al. A controlled trial of exercise rehabilitation after heart transplantation [published erratum appears in N Engl J Med. 1999;340(12):976] N Engl J Med. 1999;340(4):272-277. 
  10. Fletcher GF. Current status of cardiac rehabilitation. Am Fam Physician. 1998;58(8):1778-1782. 
  11. Turner-Boutle M, Dinnes J. On the evidence. Cardiac rehabilitation. Health Serv J. 1998;108(5619):26-27. 
  12. Thompson DR, Bowman GS. Evidence for the effectiveness of cardiac rehabilitation. Intensive Crit Care Nurs. 1998;14(1):38-48. 
  13. Limacher MC. Exercise and rehabilitation in women. Indications and outcomes. Cardiol Clin. 1998;16(1):27-36. 
  14. Peterson ED, Shaw LJ, Califf RM. Risk stratification after myocardial infarction. Ann Intern Med. 1997;126(7):561-582. 
  15. No authors listed. Physical activity and cardiovascular health. NIH Consens Statement. 1995;13(3):1-33. 
  16. Wenger NK, Froelicher ES, Smith LK, et al. Cardiac rehabilitation. Clinical Practice Guideline No. 17. AHCPR Publication No. 96-0672. Rockville, MD: Agency for Health Care Policy and Research and the National Heart, Lung, and Blood Institute; October 1995. 
  17. Thompson DR. Cardiac rehabilitation in the United Kingdom: Guidelines and audit standards. National Institute for Nursing, the British Cardiac Society and the Royal College of Physicians of London. Heart. 1996;75(1):89-93. 
  18. Fletcher GF. Statement on exercise: Benefits and recommendations for physical activity programs for all Americans. A statement for health professionals by the Committee on Exercise and Cardiac Rehabilitation of the Council on Clinical Cardiology, American Heart Association. Circulation. 1996;94(4):857-862. 
  19. Verrill D. Recommended guidelines for monitoring and supervision of North Carolina phase II/III cardiac rehabilitation programs. A position paper by the North Carolina Cardiopulmonary Rehabilitation Association. J Cardiopulm Rehabil. 1996;16(1):9-24. 
  20. Pina IL. Guidelines for clinical exercise testing laboratories. A statement for healthcare professionals from the Committee on Exercise and Cardiac Rehabilitation, American Heart Association. Circulation. 1995;91(3):912-921. 
  21. Balady GJ, Fletcher BJ, Froelicher ES, et al. AHA Medical/Scientific Statement. Cardiac Rehabilitation Programs. Dallas, TX: American Heart Association (AHA); 1994. 
  22. Squires RW, Gau GT, Miller TD, et al. Cardiovascular rehabilitation: Status, 1990. Mayo Clin Proc. 1990;65(5):749-755. 
  23. Greenland P, Chu JS. Cardiac Rehabilitation Services: Clinical Practice Guidelines. Philadelphia, PA: American College of Physicians; 1994. 
  24. Hotta SS. Cardiac rehabilitation programs. Health Technology Assessment Reports. AHCPR Pub. No. 92-0015. Rockville, MD: Agency for Healthcare Policy and Research (AHCPR), Office of Health Technology Assessment (OHTA); December 1991;3. 
  25. American College of Cardiology (ACC). Cardiovascular Rehabilitation. ACC Position Statement.  Bethesda, MD: ACC; 1985:1-6. Available at: http://www.acc.org/clinical/position/72539.pdf. Accessed January 19, 2006.
  26. Greenland P, Chu JS. Efficacy of cardiac rehabilitation services. With emphasis on patients after myocardial infarction. Ann Intern Med. 1988;109(8):650-653. 
  27. Position paper of the American Association of Cardiovascular and Pulmonary Rehabilitation: Scientific evidence of the value of cardiac rehabilitation services with emphasis on patients following myocardial infarction - Section I: Exercise conditioning component. J Cardiopulm Rehab. 1990;10:79-87. 
  28. Fletcher GF. Current status of cardiac rehabilitation. Curr Probl Cardiol. 1992;17(3):143 -203. 
  29. O'Connor GT, Buring JE, Yusuf S, et al. An overview of randomized trials of rehabilitation with exercise after myocardial infarction. Circulation. 1989;80(2):234-244. 
  30. Oldridge N, Guyatt G, Jones N, et al. Effects on quality of life with comprehensive rehabilitation after acute myocardial infarction. Am J Cardiol. 1991;67(13):1084-1089. 
  31. Forman DE, Farquhar W. Cardiac rehabilitation and secondary prevention programs for elderly cardiac patients. Clin Geriatr Med. 2000;16(3):619-629. 
  32. Ades PA, Coello CE. Effects of exercise and cardiac rehabilitation on cardiovascular outcomes. Med Clin North Am. 2000;84(1):251-265, x-xi. 
  33. Pasquali SK, Alexander KP, Peterson ED. Cardiac rehabilitation in the elderly. Am Heart J. 2001;142(5):748-755. 
  34. Ades PA. Cardiac rehabilitation and secondary prevention of coronary heart disease. N Engl J Med. 2001;345(12):892-902.
  35. Balady GJ, Ades PA, Comoss P, et al. Core components of cardiac rehabilitation/secondary prevention programs: A statement for healthcare professionals from the American Heart Association and the American Association of Cardiovascular and Pulmonary Rehabilitation Writing Group. Circulation. 2000;102(9):1069-1073.
  36. Stone JA, Cyr C, Friesen M, et al. Canadian guidelines for cardiac rehabilitation and atherosclerotic heart disease prevention: A summary. Can J Cardiol. 2001;17 Suppl B:3B-30B.
  37. Davison J. Factors that affect women's uptake of cardiac rehabilitation schemes. Prof Nurse.  2002;17(11):682-685.
  38. Cooper AF, Jackson G, Weinman J, Horne R. Factors associated with cardiac rehabilitation attendance: A systematic review of the literature. Clin Rehabil. 2002;16(5):541-552.
  39. University of York. NHS Centre for Reviews and Dissemination. Cardiac rehabilitation. Effective Health Care. 1998;4(4):1-12.
  40. Ignaszewski A, Lear SA. Cardiac rehabilitation programs. In: Canadian Cardiovascular Society 1998 Consensus Conference on the Prevention of Cardiovascular Diseases: The Role of the Cardiovascular Specialist. Ottawa, ON: Canadian Cardiovascular Society; 1998. Available at: http://www.ccs.ca/society/conferences/archives/1998/1998coneng-25.asp. Accessed January 21, 2004.
  41. Scottish Intercollegiate Guidelines Network (SIGN). Cardiac rehabilitation. A national clinical guideline. SIGN Publication No. 57. Edinburgh, Scotland: SIGN; January 2002.
  42. New Zealand Guidelines Group (NZGG). Cardiac rehabilitation. Evidence-Based Best Practice Guideline. Wellington, New Zealand: NZGG; August 2002.
  43. Jolliffe JA, Rees K, Taylor RS, et al. Exercise-based rehabilitation for coronary heart disease. Cochrane Database Syst Rev. 2001;(1):CD001800.
  44. Rees K, Taylor RS, Singh S, et al. Exercise based rehabilitation for heart failure. Cochrane Database Syst Rev. 2004,(3):CD003331.
  45. Stewart KJ, Badenhop D, Brubaker PH, et al. Cardiac rehabilitation following percutaneous revascularization, heart transplant, heart valve surgery, and for chronic heart failure. Chest. 2003;123(6):2104-2111.
  46. Giannuzzi P, Saner H, Bjornstad H, et al. Secondary prevention through cardiac rehabilitation: Position paper of the Working Group on Cardiac Rehabilitation and Exercise Physiology of the European Society of Cardiology. Eur Heart J. 2003;24(13):1273-1278.
  47. National Institute for Clinical Excellence (NICE), North of England Evidence-based Guidelines Development Project. Prophylaxis for patients who have experienced a myocardial infarction: Drug treatment, cardiac rehabilitation and dietary manipulation - guideline. Evidence-based Clinical Practice Guideline. London, UK: NICE; 2001.
  48. Institute for Clinical Systems Improvement (ICSI). Cardiac rehabilitation. Technology Assessment Report. Bloomington, MN: ICSI; 2002.
  49. Brown A, Noorani H, Taylor R, et al. A clinical and economic review of exercise-based cardiac rehabilitation programs for coronary artery disease. Technology Overview No. 11. Ottawa, ON: Canadian Coordinating Office for Health Technology Assessment (CCOHTA); August 2003.
  50. Gordon NF, Gulanick M, Costa F, et al. Physical activity and exercise recommendations for stroke survivors: An American Heart Association scientific statement from the Council on Clinical Cardiology, Subcommittee on Exercise, Cardiac Rehabilitation, and Prevention; the Council on Cardiovascular Nursing; the Council on Nutrition, Physical Activity, and Metabolism; and the Stroke Council. Circulation. 2004;109(16):2031-2041.
  51. Taylor RS, Brown A, Ebrahim S, et al. Exercise-based rehabilitation for patients with coronary heart disease: Systematic review and meta-analysis of randomized controlled trials. Am J Med. 2004;116:682–692.
  52. Centers for Medicare and Medicaid Services (CMS). Cardiac rehabilitation programs. National Coverage Determination. Coverage Issues Manual Sec. 20.10. Baltimore, MD: CMS; effective August 1, 1989. Available at: http://www.cms.hhs.gov/mcd/. Accessed January 19, 2006.
  53. Herridge ML, Stimler CE, Southard DR, et al. Depression screening in cardiac rehabilitation: AACVPR Task Force Report. J Cardiopulm Rehabil. 2005;25(1):11-13.
  54. Arnold JM, Liu P, Demers C, et al; Canadian Cardiovascular Society. Canadian Cardiovascular Society consensus conference recommendations on heart failure 2006: Diagnosis and management. Can J Cardiol. 2006;22(1):23-45.
  55. Jolly K, Taylor RS, Lip GY, Stevens A. Home-based cardiac rehabilitation compared with centre-based rehabilitation and usual care: A systematic review and meta-analysis. Int J Cardiol. 2006;111(3):343-351.
  56. Zwisler A-D, Nissen NK, Madsen M; DANREHAB Group. Cardiac rehabilitation - a health technology assessment: Evidence from the literature and the DANREHAB trial [summary]. Copenhagen, Denmark: Danish Centre for Evaluation and Health Technology Assessment (DACEHTA); 2006.
  57. Skinner JS, Cooper A, Feder GS; Guideline Development Group. Secondary prevention for patients following a myocardial infarction: Summary of NICE guidance. Heart. 2007;93(7):862-864.
  58. Thomas RJ, King M, Lui K, et al; AACVPR; ACC; AHA; American College of Chest Physicians; American College of Sports Medicine; American Physical Therapy Association; Canadian Association of Cardiac Rehabilitation; European Association for Cardiovascular Prevention and Rehabilitation; Inter-American Heart Foundation; National Association of Clinical Nurse Specialists; Preventive Cardiovascular Nurses Association; Society of Thoracic Surgeons. AACVPR/ACC/AHA 2007 performance measures on cardiac rehabilitation for referral to and delivery of cardiac rehabilitation/secondary prevention services endorsed by the American College of Chest Physicians, American College of Sports Medicine, American Physical Therapy Association, Canadian Association of Cardiac Rehabilitation, European Association for Cardiovascular Prevention and Rehabilitation, Inter-American Heart Foundation, National Association of Clinical Nurse Specialists, Preventive Cardiovascular Nurses Association, and the Society of Thoracic Surgeons. J Am Coll Cardiol. 2007;50(14):1400-1433.
  59. National Institute for Health and Clinical Excellence (NICE). Secondary prevention in primary and secondary care for patients following a myocardial infarction. NICE Clinical Guideline 48. London, UK: NICE; May 2007.
  60. Centers for Disease Control and Prevention (CDC). Receipt of outpatient cardiac rehabilitation among heart attack survivors--United States, 2005. MMWR Morb Mortal Wkly Rep. 2008;57(4):89-94.
  61. Canyon S, Meshgin N. Cardiac rehabilitation - reducing hospital readmissions through community based programs. Aust Fam Physician. 2008;37(7):575-577.
  62. Austin J, Williams WR, Ross L, Hutchison S. Five-year follow-up findings from a randomized controlled trial of cardiac rehabilitation for heart failure. Eur J Cardiovasc Prev Rehabil. 2008;15(2):162-167.
  63. American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR). Guidelines for Cardiac Rehabilitation and Secondary Prevention Programs. 4th ed. Champaign, IL: Human Kinetics; 2004.
  64. Hamm LF. Cardiac rehabilitation in the United States: From evidence to application. Kardiol Pol. 2008;66:921-924.
  65. Centers for Medicare and Medicaid Services (CMS). NCD for cardiac rehabilitation programs. Pub No. 100-3, section 20.10, version 2. Medicare Coverage Database. Baltimore, MD: CMS; June 23, 2006.
  66. Ueno A, Tomizawa Y. Cardiac rehabilitation and artificial heart devices. J Artif Organs. 2009;12(2):90-97.
  67. Fernandez RS, Davidson P, Griffiths R, et al. A pilot randomised controlled trial comparing a health-related lifestyle self-management intervention with standard cardiac rehabilitation following an acute cardiac event: Implications for a larger clinical trial. Aust Crit Care. 2009;22(1):17-27.
  68. Hammill BG, Curtis LH, Schulman KA, Whellan DJ. Relationship between cardiac rehabilitation and long-term risks of death and myocardial infarction among elderly Medicare beneficiaries. Circulation. 2010;121(1):63-70.
  69. Taylor RS, Dalal H, Jolly K, et al. Home-based versus centre-based cardiac rehabilitation. Cochrane Database Syst Rev. 2010;(1):CD007130.
  70. Davies EJ, Moxham T, Rees K, et al. Exercise based rehabilitation for heart failure. Cochrane Database Syst Rev. 2010;(4):CD003331.
  71. Piepoli MF, Corrà U, Benzer W, et al; Cardiac Rehabilitation Section of the European Association of Cardiovascular Prevention and Rehabilitation. Secondary prevention through cardiac rehabilitation: From knowledge to implementation. A position paper from the Cardiac Rehabilitation Section of the European Association of Cardiovascular Prevention and Rehabilitation. Eur J Cardiovasc Prev Rehabil. 2010;17(1):1-17.
  72. American Association of Cardiovascular and Pulmonary Rehabilitation; American College of Cardiology Foundation; American Heart Association Task Force on Performance Measures (Writing Committee to Develop Clinical Performance Measures for Cardiac Rehabilitation), Thomas RJ, King M, Lui K, et al. AACVPR/ACCF/AHA 2010 Update: Performance Measures on Cardiac Rehabilitation for Referral to Cardiac Rehabilitation / Secondary Prevention Services Endorsed by the American College of Chest Physicians, the American College of Sports Medicine, the American Physical Therapy Association, the Canadian Association of Cardiac Rehabilitation, the Clinical Exercise Physiology Association, the European Association for Cardiovascular Prevention and Rehabilitation, the Inter-American Heart Foundation, the National Association of Clinical Nurse Specialists, the Preventive Cardiovascular Nurses Association, and the Society of Thoracic Surgeons. J Am Coll Cardiol. 2010;56(14):1159-1167.
  73. Prior PL, Hachinski V, Unsworth K, et al. Comprehensive cardiac rehabilitation for secondary prevention after transient ischemic attack or mild stroke: I: Feasibility and risk factors. Stroke. 2011;42(11):3207-3213.
  74. Balady GJ, Ades PA, Bittner VA, et al.; American Heart Association Science Advisory and Coordinating Committee. Referral, enrollment, and delivery of cardiac rehabilitation/secondary prevention programs at clinical centers and beyond: A presidential advisory from the American Heart Association. Circulation. 2011;124(25):2951-2960.
  75. Isaksen K, Morken IM, Munk PS, Larsen AI. Exercise training and cardiac rehabilitation in patients with implantable cardioverter defibrillators: A review of current literature focusing on safety, effects of exercise training, and the psychological impact of programme participation. Eur J Cardiovasc Prev Rehabil. 2012;19(4):804-812.
  76. Tikkanen AU, Oyaga AR, Riano OA, et al. Paediatric cardiac rehabilitation in congenital heart disease: A systematic review. Cardiol Young. 2012;22(3):241-250.
  77. King M, Bittner V, Josephson R, et al. Medical director responsibilities for outpatient cardiac rehabilitation/secondary prevention programs: 2012 update: A statement for health care professionals from the American Association of Cardiovascular and Pulmonary Rehabilitation and the American Heart Association. Circulation. 2012;126(21):2535-2543.
  78. Pack QR, Mansour M, Barboza JS, et al. An early appointment to outpatient cardiac rehabilitation at hospital discharge improves attendance at orientation: A randomized, single-blind, controlled trial. Circulation. 2013;127(3):349-355.
  79. Beauchamp A, Worcester M, Ng A, et al. Attendance at cardiac rehabilitation is associated with lower all-cause mortality after 14 years of follow-up. Heart. 2013;99(9):620-625.
  80. Centers for Medicare & Medicaid Services (CMS). Decision memo for cardiac rehabilitation (CR) programs - chronic heart failure (CAG-00437N). Medicare Coverage Database. Baltimore, MD: CMS; February 18, 2014.
  81. Centers for Medicare and Medicaid Services (CMS). National coverage determination (NCD) for cardiac rehabilitation programs for chronic heart failure (20.10.1). Baltimore, MD: CMS; February 18, 2014.
  82. Shibata S, Fu Q, Bivens TB, et al. Short-term exercise training improves the cardiovascular response to exercise in the postural orthostatic tachycardia syndrome. J Physiol. 2012;590(Pt 15):3495-3505.
  83. Benarroch EE. Postural tachycardia syndrome: A heterogeneous and multifactorial disorder. Mayo Clin Proc. 2012;87(12):1214-1225.
  84. Freeman R, Kaufman H. Postural tachycardia syndrome. UpToDate Inc., Waltham, MA. Last reviewed September 2014.
  85. Gaalema DE, Cutler AY, Higgins S3, Ades PA. Smoking and cardiac rehabilitation participation: Associations with referral, attendance and adherence. Prev Med. 2015;80:67-74.
  86. Huang K, Liu W, He D, et al. Telehealth interventions versus center-based cardiac rehabilitation of coronary artery disease: A systematic review and meta-analysis. Eur J Prev Cardiol. 2015;22(8):959-971.
  87. Taylor RS, Dalal H, Jolly K, et al. Home-based versus centre-based cardiac rehabilitation. Cochrane Database Syst Rev. 2015;8:CD007130.
  88. Zwisler AD, Norton RJ, Dean SG, et al. Home-based cardiac rehabilitation for people with heart failure: A systematic review and meta-analysis. Int J Cardiol. 2016;221:963-969.
  89. Sibilitz KL, Berg SK, Tang LH, et al. Exercise-based cardiac rehabilitation for adults after heart valve surgery. Cochrane Database Syst Rev. 2016;3:CD010876.
  90. Parreira LB, Jardim PC, Sousa AL, et al. Cardiac rehabilitation in hypertensive patients: Comparison between two protocols. J Hypertens. 2016;34 Suppl 2:e99.
  91. Satou GM. Sinus venosus atrial septal defects. Medscape. Pediatrics: Cardiac Disease and Critical Care Medicine. Last updated September 10, 2015. Available at: http://emedicine.medscape.com/article/892151-overview. Accessed October 11, 2017.
  92. Rauch B, Davos CH, Doherty P, et al; ‘Cardiac Rehabilitation Section’, European Association of Preventive Cardiology (EAPC), in cooperation with the Institute of Medical Biometry and Informatics (IMBI), Department of Medical Biometry, University of Heidelberg, and the Cochrane Metabolic and Endocrine Disorders Group, Institute of General Practice, Heinrich-Heine University, Düsseldorf, Germany. The prognostic effect of cardiac rehabilitation in the era of acute revascularisation and statin therapy: A systematic review and meta-analysis of randomized and non-randomized studies - The Cardiac Rehabilitation Outcome Study (CROS). Eur J Prev Cardiol. 2016;23(18):1914-1939.
  93. Fukui S, Ogo T, Takaki H, et al. Efficacy of cardiac rehabilitation after balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension. Heart. 2016;102(17):1403-1409.
  94. Sibilitz KL, Berg SK, Rasmussen TB, et al. Cardiac rehabilitation increases physical capacity but not mental health after heart valve surgery: A randomised clinical trial. Heart. 2016;102(24):1995-2003.
  95. Connolly HM. Surgical and percutaneous closure of atrial septal defects in adults. UpToDate Inc., Waltham, MA. Last reviewed September 2017.
  96. Risom SS, Zwisler AD, Johansen PP, et al. Exercise-based cardiac rehabilitation for adults with atrial fibrillation. Cochrane Database Syst Rev. 2017;2:CD011197. 
  97. Redwood DR, Goldstein RE, Hirshfeld J, et al. Exercise performance after septal myotomy and myectomy in patients with obstructive hypertrophic cardiomyopathy. Am J Cardiol. 1979;44(2):215-220.
  98. Franz M, Bahrmann P, Berndt A, et al. Surgical therapy of infective endocarditis. General aspects and case report. Med Klin (Munich). 2008;103(5):349-355.
  99. Kissel CK, Nikoletou D. Cardiac rehabilitation and exercise prescription in symptomatic patients with non-obstructive coronary artery disease - a systematic review. Curr Treat Options Cardiovasc Med. 2018;20(9):78.
  100. Rothe D, Cox-Kennett N, Buijs DM, et al. Cardiac rehabilitation in patients with lymphoma undergoing autologous hematopoietic stem cell transplantation: A cardio-oncology pilot project. Can J Cardiol. 2018;34(10S2):S263-S269.
  101. Centers for Medicare & Medicaid Services (CMS). Decision memo for cardiac rehabilitation programs (CAG-00089R). Medicare Coverage Database. Baltimore, MD: CMS; March 22, 2006.
  102. Centers for Medicare & Medicaid Services (CMS). Decision memo for cardiac rehabilitation programs (CAG-00089R2). Medicare Coverage Database. Baltimore, MD: CMS; February 22, 2010.
  103. Maron MS. Hypertrophic cardiomyopathy: Nonpharmacologic treatment of left ventricular outflow tract obstruction. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed January 2019.
  104. American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR). Program certification FAQs. Chicago, IL: AACVPR; 2018. Available at: https://www.aacvpr.org/Certification/Program-Certification/Program-Certification-FAQs#Physician_Supervision. Accessed January 22, 2019.
  105. CGS Administrators, LLC. Cardiac rehabilitation: Coverage and documentation requirements. April 18, 2018. Available at: https://www.cgsmedicare.com/parta/pubs/news/2018/04/cope7245.html. Accessed January 22, 2019.