Cardiac Event Monitors

Number: 0073

Policy

1. Aetna considers external intermittent cardiac event monitors (i.e., external loop recorders) and external intermittent cardiac event monitors with real-time data transmission and analysis (e.g., eCardio eVolution) medically necessary for any of the following conditions:

   1. To document a suspected arrhythmia in persons with a non-diagnostic Holter monitor or 48 hour telemetry (e.g., suspected atrial fibrillation as cause of cryptogenic stroke), or in persons whose symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring (see CPB 0019 - Holter Monitors); or 
   2. To document ST segment depression for suspected ischemia; or
   3. To document the benefit after initiating drug therapy for an arrhythmia; or
   4. To document the recurrence of an arrhythmia after discontinuation of drug therapy; or
   5. To document the results after an ablation procedure for arrhythmia; or
   6. To evaluate syncope and lightheadedness in persons with a non-diagnostic Holter monitor or 48 hour telemetry, or in persons whose symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring.

   Aetna considers external loop recorders experimental and investigational for all other indications because their effectiveness for indications other than the ones listed above has not been established.

2. Aetna considers mobile cardiovascular telemetry (MCT) (e.g., CardioNet Mobile Cardiac Outpatient Telemetry (MCOT) Service; Cardiac Telecom and Health Monitoring Services of America’s Telemetry @ Home Service; Heartbreak ECAT (External Cardiac Ambulatory Telemetry) (Med net Healthcare Technologies), HEARTLink™ II ECG Arrhythmia Detector and Alarm System by Cardiac Telecom Corporation, LifeStar ACT by LifeWatch®, Inc., a subsidiary of Card Guard Scientific, SAVI® (Mediacom), Telemetry™ (Scott Care Cardiovascular Solutions) and Trove® (Biomedical Systems)) medically necessary when either criteria in A or B is met:

   1. Evaluation of recurrent unexplained episodes of presyncope, syncope, palpitations or dizziness when both of the following (1 and 2) are met:

      1. A cardiac arrhythmia is suspected as the cause of the symptoms; and
      2. Members have a non-diagnostic Holter monitor or 48 hour telemetry, or symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring; or

   2. For evaluation of members with suspected atrial fibrillation as a cause of cryoptogenic stroke who have had a nondiagnostic Holter monitor or 48 hour telemetry.

   Aetna considers MCT experimental and investigational for other indications because its effectiveness for indications other than the ones listed above has not been established.

3. Aetna considers an implantable loop recorder (e.g., Reveal Insertable Loop Recorder by Medtronic, Inc.) medically necessary for the following indications:

   1. A cardiac arrhythmia is suspected as the cause of the symptoms; and
   2. Either of the following criteria is met:
      
      
      1. For persons with heart failure, prior myocardial infarction or significant electrocardiogram (ECG) abnormalities (see appendix), noninvasive ambulatory monitoring, consisting of 30-day presymptom external loop recordings or MCT, fails to establish a definitive diagnosis; or
      2. For persons without heart failure, prior myocardial infarction or significant ECG abnormalities (see appendix), symptoms occur so infrequently and unpredictably (less frequently than once per month) that noninvasive ambulatory monitoring (MCT or external loop recorders) are unlikely to capture a diagnostic ECG; or
         
   3. For evaluation of recurrent unexplained episodes of pre-syncope, syncope, "seizures", palpitations, or dizziness when both of the following criteria are met:
      
      
      1. A cardiac arrhythmia is suspected as the cause of the symptoms; and
      2. Members have a non-diagnostic Holter monitor or 48 hour telemetry, or symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring; or
         
   4. For evaluation of members with suspected atrial fibrillation as a cause of cryoptogenic stroke who have had a nondiagnostic Holter monitor or 48 hour telemetry.

4. Aetna considers implantable loop recorders experimental and investigational for all other indications because their effectiveness for indications other than the ones listed above has not been established.

   Note: Depending on clinical presentation, the individual may have had a negative or non-diagnostic electrophysiological study (EPS); however, EPS is no longer considered a prerequisite to insertion of an implantable loop recorder.

5. Aetna considers the use of long-term (greater than 48 hours) external ECG monitoring by continuous rhythm recording and storage (e.g., Zio Patch) medically necessary for the following indications:

   1. To evaluate syncope and lightheadedness in persons with a non-diagnostic Holter monitor or 48 hour telemetry, or in persons whose symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring (see CPB 0019 - Holter Monitors); or
   2. To document an arrhythmia in persons with a non-diagnostic Holter monitor or 48 hour telemetry, or in persons whose symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring.  

6. Aetna considers the following experimental and investigational because their clinical value has not been established.

   1. Biotronik BioMonitor
   2. CardioPatch
   3. Kardia Mobile (previously known as AliveCore Mobile ECG, AliveCor Heart Monitor (iPhoneECG))
   4. Mobile patient management systems (e.g., BodyGuardian Remote Monitoring System, and iHEART)
   5. Self-monitoring ECG technologies or the ViSi Mobile Monitoring System
   6. Zio Patch for documentation of responses following initiation of drug therapy for arrhythmia

Requests for cardiac event monitoring that do not meet the above criteria and requests for repeat studies within 1 year of a previous study are subject to medical necessity review.

Background

Cardiac event monitors are small portable devices worn by a patient during normal activity for up to 30 days.  The device has a recording system capable of storing several minutes of the individual's electrocardiogram (EKG) record.  The patient can initiate EKG recording during a symptomatic period of arrhythmia.  Cardiac event monitors have primarily been used to diagnose and evaluate cardiac arrhythmias.  These monitors are particularly useful in obtaining a record of arrhythmia that would not be discovered on a routine EKG or an arrhythmia that is so infrequent that it is not detected during a 24-hour period by a Holter monitor.

Two different types of cardiac event monitors are available.  Pre-symptom (looping memory) event monitors are equipped with electrodes attached to the chest, and are able to capture EKG rhythms before the cardiac event monitor is triggered (pre-symptom recording) (Healthwise, 2003).  This feature is especially useful for people who lose consciousness when arrhythmias occur. 

Post-symptom event monitors do not have chest electrodes (Healthwise, 2003).  One type of post-symptom event monitor is worn on the wrist.  When symptoms occur, the patient presses a button to trigger an EKG recording.  Another type of post-symptom event monitor is a device that the patient carries within easy reach.  When symptoms occur, the patient presses the electrodes on the device against their chest and presses a button to trigger the EKG recording.

Cardiac event monitors have been developed with automatic trigger capabilities, which are designed to automatically trigger an EKG recording when certain arrhythmias occur.  Automated trigger cardiac event monitors are thought to be more sensitive, but less specific, than manually-triggered cardiac event monitors for significant cardiac arrhythmias.  The simplest automatic trigger cardiac event monitors detect a single type of arrhythmia (e.g., atrial fibrillation), whereas more sophisticated monitors are capable of detecting several types of arrhythmias (e.g., PDSHEART, 2001; Instromedix, 2002; LifeWatch, 2004; Medicomp, 2005; eCardio Diagnostics, 2004).  Automatic trigger cardiac event monitors may be especially useful for persons with asymptomatic arrhythmias, persons with syncope, and other persons (children, persons with intellectual disabilities) who can not reliably trigger the monitor when symptoms occur.

Cardiac event monitors may come with 24-hour remote monitoring.  Usually, EKG results are transmitted over standard phone lines at the end of each day to an attended monitoring center, where a technician screens EKG results and notifies the patient’s physician of any significant abnormal results, based on predetermined notification criteria.  Newer cardiac event monitors allow EKG results to be transmitted via e-mail over the internet (CardioPhonics, 2006).  Some cardiac event monitors allow the patient to transmit EKG over standard telephone lines to the attended monitoring center immediately after symptoms occur (e.g., Versweyveld, 2001; Transmedex, 2001); other cardiac event monitors have been adapted to also allow immediate transmission of EKG results by cellular telephone (Philips, 2003; Schiller, 2004; CRY, 2004; HealthFrontier, 2004).  If test results suggest a life-threatening emergency, monitoring center personnel may instruct the patient to go to the hospital or call an ambulance (Daja et al, 2001).  The development of mobile technology may extend the use of cardiac event monitors from primarily diagnostic purposes to use primarily as an alarm system, to allow rapid intervention for the elderly and others at increased risk of cardiac events (Cox, 2003; Lloyds, 1999).

Standard cardiac event monitors come with 5 to 10 mins of memory.  Cardiac event monitors with expanded memory capabilities have been developed, extending memory from approximately 20 to 30 mins (Instromedix, 2002; LifeWatch, 2002; Philips Medical Systems, 2003; PDSHeart, 2006) to as much as several hours (CardioPhonics, 2001; CardioPhonics, 2006).  Extended memory is especially useful for automatic trigger cardiac event monitors, because the automatic trigger may not reliably discriminate between clinically significant arrhythmias (true positives) and EKG artifacts (false positives), such that a more limited memory would be filled with false positives.

Mobile cardiovascular telemetry (MCT) refers to non-invasive ambulatory cardiac event monitors with extended memory capable of continuous measurement of heart rate and rhythm over several days, with transmission of results to a remote monitoring center.  Mobile cardiovascular telemetry is similar to standard cardiac telemetry used in the hospital setting.

CardioNet (Philadelphia, PA) has developed an MCT device with extended memory, automatic electrocardiogram (ECG) arrhythmia detector and alarm that is incorporated into a service that CardioNet has termed "Mobile Cardiac Outpatient Telemetry (MCOT)."  The CardioNet device couples an automatic arrhythmia detector and cellular telephone transmission so that abnormal EKG waveforms can automatically be transmitted immediately to the remote monitoring center.  The CardioNet device also has an extended memory characteristic of digital Holter monitors; the CardioNet device is capable of storing up to 96 hours of EKG waveforms.  These ECG results are transmitted over standard telephone lines to the remote monitoring center at the end of each day.  The physician receives both urgent and daily reports.

The manufacturer states that an important advantage of MCOT is that it is capable of detecting asymptomatic events and transmitting them immediately, even when the patient is away from home, allowing timely intervention should a life-threatening arrhythmia may occur.  The CardioNet device’s extended memory allows the physician to examine any portion of the ECG waveform over an entire day.  This extended memory ensures that it does not fill with EKG artifact (false positives) where the CardioNet’s automated ECG trigger is unable to reliably discriminate between artifact and significant arrhythmias (true positives).  Potential uses of MCOT include diagnosis of previously unrecognized arrhythmias, ascertainment of cause of symptoms, and initiation of anti-arrhythmic drug therapy.

The CardioNet ambulatory ECG arrhythmia detector and alarm is cleared for marketing by the Food and Drug Administration (FDA) based on a 510(k) premarket notification due to the FDA’s determination that the CardioNet device was substantially equivalent to devices that were currently on the market.  The CardioNet device is not intended for monitoring patients with life-threatening arrhythmias (FDA, 2002).

There is reliable evidence that MCT is superior to patient-activated external loop recorders for diagnosing cardiac arrhythmias.  Rothman et al (2007) reported on a randomized controlled clinical study comparing the diagnostic yield of MCT (CardioNet MCOT) to patient-activated external looping event monitors for symptoms thought to be due to an arrhythmia.  Subjects with symptoms of syncope, pre-syncope, or severe palpitations who had a non-diagnostic 24-hour Holter monitor were randomized to MCT or an external loop recorder for up to 30 days.  The primary endpoint was the confirmation or exclusion of a probable arrhythmic cause of their symptoms.  A total of 266 patients who completed the monitoring period were analyzed.  A diagnosis was made in 88 % of MCT subjects compared to 75 % of subjects with standard loop recorders (p = 0.008).  The authors noted that cardiac arrhythmias without associated symptoms, but nonetheless capable of causing the index symptoms, were the major determining factor accounting for the difference in diagnostic yield of MCT and patient-activated external loop recorders.

There is also evidence to suggest that MCT is superior to auto-triggered external loop recorders for diagnosing symptoms thought to be due to a cardiac arrhythmia.  Loop recorders with auto-trigger algorithms have been used to improve the diagnostic yield of event monitors (Strickberger et al, 2006).  Rothman et al (2007) explained that their study of MCT was not designed to evaluate auto-triggered loop recorders, as this type of recorder was not available at all study sites.  However, 2 of the 17 study sites used looping event recorders with an auto-trigger algorithm in all of their randomized patients (Rothman et al, 2007).  A total of 49 subjects, or 16 % of the randomized population were from these 2 sites.  In a post-hoc analysis of this subgroup of patients, a diagnosis was made in 88 % of MCT subjects compared to 46 % of patients with auto-triggered external loop recorders.  One possible factor accounting for the poor diagnostic yield of the auto-trigger loop recorders employed in this study is that they may have had limited memory which quickly filled with artifact.  In addition, the CardioNet MCOT device used in this study uses dual EKG leads, whereas the auto-trigger loop recorders may have used single leads.

One limitation of the study by Rothman et al (2007) was the lack of blinding of the investigators or subjects.  The investigators sought to overcome this bias by having all monitoring strips and diagnoses evaluated by another electrophysiologist that was blinded to assignment.  Another limitation of this study is that it did not explore the potential for work-up bias; the study did not describe whether any of the study subjects had ever had previous work-ups for cardiac arrhythmias that included evaluation with an external loop recorder.

A number of retrospective uncontrolled studies have been published that have described the experience with MCT.  Olson et al (2007) retrospectively examined the records of 122 consecutive patients evaluated using MCT for palpitations (n = 76), pre-syncope/syncope (n = 17), or to monitor the effectiveness of anti-arrhythmic therapy (n = 29).  The investigators reported on the proportion of patients with syncope/pre-syncope and palpitations whose diagnosis was established by MCT, and the proportion of patients monitored for medication titration who had dosage adjustments.  This study is of similar design to an earlier study by Joshi et al (2005), which reported on the first 100 consecutive patients monitored by MCT. 

Vasamreddy et al (2006) reported on a small (n = 19) prospective exploratory study examining the feasibility and results of using MCT for monitoring patients with atrial fibrillation before and after catheter ablation for atrial fibrillation.  The authors concluded that MCT has potential utility for this use.  The authors noted, however, that poor patient compliance with the study's MCT monitoring protocol represented an important limitation; only 10 of 19 subjects that were enrolled in the study completed the protocol, which required subjects to wear the MCT monitor 5 days per month for 6 months following the ablation.

Cardiac Telecom Corporation (Greensburg, PA) and Health Monitoring Services of America (Boca Raton, FL) have developed an MCT service called "Telemetry @ Home" that shares many similarities to the CardioNet Service.  The Telemetry @ Home Service utilizes Cardiac Telecom’s Heartlink II Monitor, which has automatic arrhythmia detection and extended memory.  The Heartlink II Monitor is able to wirelessly transmit abnormal EKG waveforms from a base station in the home to a remote monitoring center.  Unlike the CardioNet Service, the Heartlink II Monitor does not have a built-in cellular telephone, so that the monitor does not automatically transmit abnormal waveforms when the patient is away from home out of range of the base station.  The Heartlink II Monitor was cleared by the FDA based upon a 510(k) premarket notification.

Biowatch Medical (Columbia, SC) offers an MCT service called "Vital Signs Transmitter (VST)" that shares many similarities to other MCT services.  According to the manufacturer, VST provides continuous, real-time, wireless ambulatory patient monitoring of 2 ECG channels plus respiration and temperature (Biowatch Medical. 2008; Gottipaty et al, 2008).  The VST is a wireless belt-like device with non-adhesive electrodes that is worn around the patient's chest.  The VST has an integrated microprocessor and wireless modem to automatically detect and transmit abnormal ECG waveforms.  The monitor transmits ECG data via an integrated cellular telephone, when activated by the patient or by the monitor’s real-time analysis software, to a central monitoring station, where the tracing is analyzed by technicians.  The technicians can then notify the patient’s physician of any serious arrhythmias, transmit ECG tracings, and provide patient intervention if required.  The monitoring center also provides daily reports that can be accessed by the patient's physician over the Internet.  According to the manufacturer, a new VST device is being developed that will also provide data on the patient's oxygen saturation, blood pressure, and weight (Biowatch Medical, 2008).  The VST was cleared by the FDA based on a 510(k) premarket notification.

Lifewatch Inc. (Rosemount, IL) has developed an MCT service called LifeStar Ambulatory Cardiac Telemetry (ACT).  The LifeStar ACT is similar to the CardioNet MCOT in that it has built-in cellular transmission so that results can be transmitted away from home.  The LifeStar ACT cardiac monitoring system utilizes an auto-trigger algorithm to detect atrial fibrillation, tachycardia, bradycardia, and pauses, and requires no patient intervention to capture or transmit an arrhythmia when it occurs.  The device can also be manually triggered by the patient during symptoms.  Upon arrhythmia detection or manual activation, the LifeStar ACT transmits data via the integrated cellular telephone to LifeWatch, where the ECG is analyzed.  The LifeStar ACT has a longer continuous memory loop that can be retrieved as needed by the monitoring center.  The LifeWatch ACT was cleared by the FDA based on a 510(k) premarket notification.

A systematic evidence review of remote cardiac monitoring prepared for the Agency for Healthcare Research and Quality by the ECRI Evidence-based Practice Center (AHRQ, 2007) reached the following conclusions about the evidence for MCT: "This study [by Rothman et al, 2007] was a high-quality multicenter study with few limitations.  Therefore, the evidence is sufficient to conclude that real-time continuous attended monitoring leads to change in disease management in significantly more patients than do certain ELRs [external loop recorders].  However, because this is a single multicenter study, the strength of evidence supporting this conclusion is weak.  Also, the conclusion may not be applicable to ELRs with automatic event activation, as this model was underrepresented in the randomized controlled trial (RCT) [by Rothman et al, 2007] (only 16 % of patients used this model)."

The Zio Patch (iRhythm Technologies, Inc., San Francisco, CA) is a recording device that provides continuous single-lead ECG data for up to 14 days (Mittal et al, 2011).  The Zio Patch uses a patch that is placed on the left pectoral region.  The patch does not require patient activation.  However, a button on the patch can be pressed by the patient to mark a symptomatic episode.  At the end of the recording period, the patient mails back the recorder in a prepaid envolope to a central monitoring station(Mittal et al, 2011).  A report is provided to the ordering physician within a few days.  The manufacturer states that it is indicated for use in patients who may be asymptomatic or who may suffer from transient symptoms (e.g., anxiety, dizziness, fatigue, light-headedness, palpitations, pre-syncope, shortness of breath, and syncope).  The Zio ECG Utilization Service (ZEUS) system is a comprehensive system that processes and analyzes received ECG data captured by long-duration, single-lead, continuous recording diagnostic devices (e.g., the Zio Patch and Zio Event Card).  However, the clinical outcomes and cost-effectiveness of extended cardiac monitoring by means of the Zito Patch, the ZEUS system and similar devices have not been shown to be superior to other available approaches.  Mittal et al (2011) noted that "clinical experience [with the Zio Patch] is currently lacking".  The author stated that it is not known how well patients can tolerate the patch for 1 to 2 weeks, and whether the patch can yield a high-quality artifact-free ECG recording through the entire recording period.  The authors stated, furthermore, that "the clinical implications of not having access to ECG information within the recording period need to be determined".

Rosenberg et al (2013) compared the Zio Patch, a single-use, non-invasive waterproof long-term continuous monitoring patch, with a 24-hour Holter monitor in 74 consecutive patients with paroxysmal atrial fibrillation (AF) referred for Holter monitoring for detection of arrhythmias.  The Zio Patch was well-tolerated, with a mean monitoring period of 10.8 +/- 2.8 days (range of 4 to 14 days).  Over a 24-hour period, there was excellent agreement between the Zio Patch and Holter for identifying AF events and estimating AF burden.  Although there was no difference in AF burden estimated by the Zio Patch and the Holter monitor, AF events were identified in 18 additional individuals, and the documented pattern of AF (persistent or paroxysmal) changed in 21 patients after Zio Patch monitoring.  Other clinically relevant cardiac events recorded on the Zio Patch after the first 24 hours of monitoring, including symptomatic ventricular pauses, prompted referrals for pacemaker placement or changes in medications.  As a result of the findings from the Zio Patch, 28.4 % of patients had a change in their clinical management.  The authors concluded that the Zio Patch was well-tolerated, and allowed significantly longer continuous monitoring than a Holter, resulting in an improvement in clinical accuracy, the detection of potentially malignant arrhythmias, and a meaningful change in clinical management.  Moreover, they stated that further studies are necessary to examine the long-term impact of the use of the Zio Patch in AF management.

Turakhia and colleagues (2013) noted that although extending the duration of ambulatory electrocardiographic monitoring beyond 24 to 48 hours can improve the detection of arrhythmias, lead-based (Holter) monitors might be limited by patient compliance and other factors.  These researchers, therefore, evaluated compliance, analyzable signal time, interval to arrhythmia detection, and diagnostic yield of the Zio Patch, a novel leadless, electrocardiographic monitoring device in 26,751 consecutive patients.  The mean wear time was 7.6 ± 3.6 days, and the median analyzable time was 99 % of the total wear time.  Among the patients with detected arrhythmias (60.3 % of all patients), 29.9 % had their first arrhythmia and 51.1 % had their first symptom-triggered arrhythmia occur after the initial 48-hour period.  Compared with the first 48 hours of monitoring, the overall diagnostic yield was greater when data from the entire Zio Patch wear duration were included for any arrhythmia (62.2 % versus 43.9 %, p < 0.0001) and for any symptomatic arrhythmia (9.7 % versus 4.4 %, p < 0.0001).  For paroxysmal atrial fibrillation (AF), the mean interval to the first detection of AF was inversely proportional to the total AF burden, with an increasing proportion occurring after 48 hours (11.2 %, 10.5 %, 20.8 %, and 38.0 % for an AF burden of 51 % to 75 %, 26 % to 50 %, 1 % to 25 %, and less than 1 %, respectively).  The authors concluded that extended monitoring with the Zio Patch for less than or equal to 14 days is feasible, with high patient compliance, a high analyzable signal time, and an incremental diagnostic yield beyond 48 hours for all arrhythmia types.  These findings could have significant implications for device selection, monitoring duration, and care pathways for arrhythmia evaluation and AF surveillance.

Higgins (2013) stated that a number of substantial improvements to the 60-year old concept of the Holter monitor have recently been developed.  One promising advance is the Zio Patch (iRhythm Technologies, Inc., CA), a small 2 × 5-inch patch, which can continuously record up to 14 days of a single ECG channel of cardiac rhythm without the need for removal during exercise, sleeping or bathing.  Its ease-of-use, which enables optimal long-term monitoring, has been established in the ambulatory setting, although some insurance carriers have been reluctant to reimburse appropriately for this advance, an issue characteristic of other heart monitors, treated as 'loss-leaders'.  In this article, in addition to discussing possible reasons for this reluctance, a novel model for direct-to-consumer marketing of heart monitoring, outside of the traditional health insurance reimbursement model, is also presented.  Additional current and future advances in heart rhythm recording are also discussed.  Such potentially revolutionary opportunities have only recently become possible as a result of technologic advances.

The Center for Medicare and Medicaid Services (CMS) (2004) has determined that an ambulatory cardiac monitoring device or service is eligible for Medicare coverage only if it can be placed into the following categories:

1. Patient/Event Activated Intermittent Recorders

   1. Pre-symptom memory loop (insertable or non-insertable)

      1. Attended;
      2. Non-attended.

   2. Post-symptom (no memory loop)

      • Non-attended

2. Non-activated Continuous Recorders

   1. Dynamic electrocardiography
   2. Non-attended.

The CMS has determined that an ambulatory cardiac monitoring device or service is not covered if it does not fit into these categories.  The CMS noted that it may create new ambulatory electrocardiographic monitoring device categories "if published, peer-reviewed clinical studies demonstrate evidence of improved clinical utility, or equal utility with additional advantage to the patient, as indicated by improved patient management and/or improved health outcomes in the Medicare population (such as superior ability to detect serious or life-threatening arrhythmias) as compared to devices or services in the currently described categories".

Hanke et al (2009) noted that 24-hr Holter monitoring (24HM) is commonly used to assess cardiac rhythm after surgical therapy of atrial fibrillation (AF).  However, this "snapshot" documentation leaves a considerable diagnostic window and only stores short-time cardiac rhythm episodes.  To improve accuracy of rhythm surveillance after surgical ablation therapy and to compare continuous heart rhythm surveillance versus 24HM follow-up intra-individually, these investigators evaluated a novel implantable continuous cardiac rhythm monitoring (IMD) device (Reveal XT 9525, Medtronic Inc., Minneapolis, MN).  A total of 45 cardiac surgical patients (male 37, mean age of 69.7+/-9.2 years) with a mean pre-operative AF duration of 38 +/- 45 m were treated with either left atrial epicardial high-intensity focus ultrasound ablation (n = 33) or endocardial cryothermy (n = 12) in case of concomitant mitral valve surgery.  Rhythm control readings were derived simultaneously from 24HM and IMD at 3-month intervals with a total recording of 2,021 hours for 24HM and 220,766 hours for IMD.  Mean follow-up was 8.30 +/- 3.97 m (range of 0 to 12 m).  Mean post-operative AF burden (time period spent in AF) as indicated by IMD was 37 +/- 43 %.  Sinus rhythm was documented in 53 readings of 24HM, but in only 34 of these instances by the IMD in the time period before 24HM readings (64 %, p < 0.0001), reflecting a 24HM sensitivity of 0.60 and a negative-predictive value (NPV) of 0.64 for detecting AF recurrence.  The authors concluded that for "real-life" cardiac rhythm documentation, continuous heart rhythm surveillance instead of any conventional 24HM follow-up strategy is necessary.  This is particularly important for further judgment of ablation techniques, devices as well as anti-coagulation and anti-arrhythmic therapy.

Hindricks et al (2010) quantified the performance of the first implantable leadless cardiac monitor (ICM) with dedicated AF detection capabilities.  Patients (n = 247) with an implanted ICM who were likely to present with paroxysmal AF were selected.  A special Holter device stored 46 hours of subcutaneously recorded ECG, ICM markers, and 2 surface ECG leads.  The ICM automatic arrhythmia classification was compared with the core laboratory classification of the surface ECG.  Of the 206 analyzable Holter recordings collected, 76 (37 %) contained at least 1 episode of core laboratory classified AF.  The sensitivity, specificity, positive-predictive value, and NPV for identifying patients with any AF were 96.1 %, 85.4 %, 79.3 %, and 97.4 %, respectively.  The AF burden measured with the ICM was very well-correlated with the reference value derived from the Holter (Pearson coefficient = 0.97).  The overall accuracy of the ICM for detecting AF was 98.5 %.  The authors concluded that in this ICM validation study, the dedicated AF detection algorithm reliably detected the presence or absence of AF and the AF burden was accurately quantified.  

Ip et al (2012) examined the outcomes of surgical ablation and post-ablation AF surveillance with a leadless ICM.  A total of 45 patients with drug-refractory paroxysmal or persistent AF underwent video-assisted epicardial ablation using a bipolar radiofrequency clamp.  An ICM was implanted subcutaneously post-ablation to assess AF recurrence.  AF recurrence was defined as greater than or equal to 1 AF episode with a duration of greater than or equal to 30 s.  The device-stored data were down-loaded weekly over the internet, and all transmitted events were reviewed.  A total of 1,220 AF automatic and patient-activated AF episodes were analyzed over a follow-up of 12 +/- 3 months.  Of these episodes, 46 % were asymptomatic.  Furthermore, only 66 % of the patient-activated episodes were AF.  Recurrence of AF was highest in first 4 weeks and substantially decreased 6 months post-ablation.  The overall freedom from AF recurrence at the end of follow-up was 60 %.  When 48-hr Holter recordings were compared with the device-stored episodes, the sensitivity of the device to detect AF was 98 %, and the specificity was 71 %.  The authors concluded that ICM provides an objective measure of AF ablation success and may be useful in making clinical decisions.

The AliveCor Heart Monitor (AliveCor, Inc., San Francisco, CA) is an iPhone-enabled heart monitor that has been known as the "iPhoneECG".  It is in a thin case with 2 electrodes that snaps onto the back of an iPhone 4 or 5.  To obtain an electrocardiogram (ECG) recording, the patient just holds the device while pressing fingers from each hand onto the electrodes.  The device can also obtain an ECG from the patient's chest.  The AliveCor ECG iPhone application can record rhythm strips of any duration to be stored on the phone and uploaded securely for later analysis, sharing, or printing through AliveCor's website.  The AliveCor Heart Monitor will operate for about 100 hours on a 3.0 V coin cell battery. 

However, there is currently a lack of evidence to support the clinical value of the AliveCor Heart Monitor. Prospective, randomized controlled studies are needed to ascertain how the use of the AliveCor Heart Monitor would improve clinical outcomes in patients with cardiovascular diseases/disorders.

According to the company, research studies are currently in progress to explore effectiveness of the AliveCor Heart Monitor in the following areas:

• Expanding physician assistant/registered nurse data collection abilities
• Long-term atrial fibrillation remote monitoring
• Medication-induced QT-duration response monitoring
• Multi-specialty care integration
• Post-ablation follow-up
• Preventive pediatric care
• Stress induced rhythm morphology changes

The implantable loop recorder (ILR) is a subcutaneous, single-lead, ECG monitoring device used for diagnosis in patients with recurrent unexplained episodes of palpitations or syncope. The 2009 ESC syncope guidelines include the following recommendations for use of ILRs: 

• ILR is indicated for early phase evaluation in patients with recurrent syncope of uncertain origin, absence of high-risk criteria (see appendix), and a high likelihood of recurrence within the battery life of the device.
• An ILR is recommended in patients who have high-risk features (see appendix) in whom a comprehensive evaluation did not demonstrate a cause of syncope or lead to a specific treatment.
• An ILR should be considered to assess the contribution of bradycardia before embarking on cardiac pacing in patients with suspected or certain reflex syncope with frequent or traumatic syncopal episodes.

Ziegler et al (2012) stated that the detection of undiagnosed atrial tachycardia/atrial fibrillation (AT/AF) among patients with stroke risk factors could be useful for primary stroke prevention.  These researchers analyzed newly detected AT/AF (NDAF) using continuous monitoring in patients with stroke risk factors but without previous stroke or evidence of AT/AF.  Newly detected AT/AF (AT/AF greater than 5 mins on any day) was determined in patients with implantable cardiac rhythm devices and greater than or equal to 1 stroke risk factors (congestive heart failure, hypertension, age greater than or equal to 75 years, or diabetes).  All devices were capable of continuously monitoring the daily cumulative time in AT/AF. Of 1,368 eligible patients, NDAF was identified in 416 (30%) during a follow-up of 1.1 ± 0.7 years and was unrelated to the CHADS2 score (clinical prediction rules for estimating the risk of stroke in patients with non-rheumatic AF) (congestive heart failure, hypertension [blood pressure consistently greater than 140/90 mm Hg or hypertension treated with medication], age greater than or equal to 75 years, diabetes mellitus, previous stroke or transient ischemic attack).  The presence of AT/AF greater than 6 hours on greater than or equal to 1 day increased significantly with increased CHADS2 scores and was present in 158 (54 %) of 294 patients with NDAF and a CHADS2 score of greater than or equal to 2.  Newly detected AT/AF was sporadic, and 78 % of patients with a CHADS2 score of greater than or equal to 2 with NDAF experienced AT/AF on less than 10 % of the follow-up days.  The median interval to NDAF detection in these higher risk patients was 72 days (interquartile range: 13 to 177).  The authors concluded that continuous monitoring identified NDAF in 30 % of patients with stroke risk factors.  In patients with NDAF, AT/AF occurred sporadically, high-lighting the difficulty in detecting paroxysmal AT/AF using traditional monitoring methods.  However, AT/AF also persisted for greater than 6 hours on greater than or equal to 1 day in most patients with NDAF and multiple stroke risk factors.  Whether patients with CHADS2 risk factors but without a history of AF might benefit from implantable monitors for the selection and administration of anti-coagulation for primary stroke prevention merits additional investigation.

Cotter et al (2013) examined the usefulness of ILR with improved AF detection capability (Reveal XT) and the factors associated with AF in the setting of unexplained stroke.  A cohort study was reported of 51 patients in whom ILRs were implanted for the investigation of ischemic stroke for which no cause had been found (cryptogenic) following appropriate vascular and cardiac imaging and at least 24 hours of cardiac rhythm monitoring.  Age of patients ranged from 17 to 73 (median of 52) years.  Of the 30 patients with a shunt investigation, 22 had a patent foramen ovale (73.3 %; 95 % CI: 56.5 % to 90.1 %).  Atrial fibrillation was identified in 13 (25.5 %; 95 % confidence intervals [CI]: 13.1 % to 37.9 %) cases.  Atrial fibrillation was associated with increasing age (p = 0.018), inter-atrial conduction block (p = 0.02), left atrial volume (p = 0.025), and the occurrence of atrial premature contractions on preceding external monitoring (p = 0.004).  The median (range) of monitoring prior to AF detection was 48 (0 to 154) days.  The authors concluded that in patients with unexplained stroke, AF was detected by ILR in 25.5 %.  Predictors of AF were identified, which may help to target investigations.  They stated that ILRs may have a central role in the future in the investigation of patients with unexplained stroke.

1. in 11 (55 %) patients, stored ECGs confirmed AF at 62 ± 38 days after ablation;
2. in 4 (20 %) patients, although the ILR suggested AF, episodes actually represented sinus rhythm with frequent premature atrial contractions and/or over-sensing;
3. in 5 (25 %) patients, no AF was observed.  Episodes less than 4 hours were associated with low AF burden (less than 1 %) or false detections. 

The 1-year freedom from any episode of AF greater than 4 and greater than 12 hours was 52 % and 83 %, respectively.  The authors concluded that these findings showed that many (but not all) patients develop new AF within the first 4 months of flutter ablation.  Since external ECG monitoring for this duration is impractical, the ILR has an important role for long-term AF surveillance.  They stated that future research should be directed toward identifying the relationship between duration/burden of AF and stroke and improving existing ILR technology.

An UpToDate review on "Cryptogenic stroke" (Prabhakaran and Elkind, 2013) states that "Paroxysmal atrial fibrillation (AF), if transient, infrequent, and largely asymptomatic, may be undetected on standard cardiac monitoring such as continuous telemetry and 24 or 48-hour Holter monitors.  In a study that assessed longer-term monitoring using an outpatient telemetry system for a median duration of 21 days among 56 patients with cryptogenic stroke, paroxysmal AF was detected in 13 patients (23 %).  The median time to detection of AF was 7 days.  The majority of patients with paroxysmal AF were asymptomatic during the fleeting episodes.  Other reports have noted that the detection rate of paroxysmal AF can be increased with longer duration of cardiac monitoring, and that precursors of AF such as frequent premature atrial contractions may predict those harboring paroxysmal AF.  The optimal monitoring method – continuous telemetry, ambulatory electrocardiography, serial electrocardiography, transtelephonic ECG monitoring, or implantable loop recorders – is uncertain, though longer durations of monitoring are likely to obtain the highest diagnostic yield".

Sanna et al (2014) conducted a randomized, controlled study of 441 patients (CRYSTAL AF trial) to assess whether long-term monitoring with an insertable cardiac monitor (ICM) is more effective than conventional follow-up (control) for detecting atrial fibrillation in patients with cryptogenic stroke.  Patients 40 years of age or older with no evidence of atrial fibrillation during at least 24 hours of ECG monitoring underwent randomization within 90 days after the index event.  The primary end-point was the time to first detection of atrial fibrillation (lasting greater than 30 seconds) within 6 months.  Among the secondary end-points was the time to first detection of atrial fibrillation within 12 months.  Data were analyzed according to the intention-to-treat principle.  By 6 months, atrial fibrillation had been detected in 8.9 % of patients in the ICM group (19 patients) versus 1.4 % of patients in the control group (3 patients) (hazard ratio [HR], 6.4; 95 % confidence interval [CI]: 1.9 to 21.7; p < 0.001).  By 12 months, atrial fibrillation had been detected in 12.4 % of patients in the ICM group (29 patients) versus 2.0 % of patients in the control group (4 patients) (HR, 7.3; 95 % CI, 2.6 to 20.8; p < 0.001).  The authors concluded that ECG monitoring with an ICM was superior to conventional follow-up for detecting atrial fibrillation after cryptogenic stroke.

In the EMBRACE trial, Gladstone et al (2014) randomly assigned 572 patients 55 years of age or older, without known atrial fibrillation, who had had a cryptogenic ischemic stroke or TIA within the previous 6 months (cause undetermined after standard tests, including 24-hour electrocardiography [ECG]), to undergo additional noninvasive ambulatory ECG monitoring with either a 30-day event-triggered recorder (intervention group) or a conventional 24-hour monitor (control group).  The primary outcome was newly detected atrial fibrillation lasting 30 seconds or longer within 90 days after randomization.  Secondary outcomes included episodes of atrial fibrillation lasting 2.5 minutes or longer and anticoagulation status at 90 days.  Atrial fibrillation lasting 30 seconds or longer was detected in 45 of 280 patients (16.1 %) in the intervention group, as compared with 9 of 277 (3.2 %) in the control group (absolute difference, 12.9 percentage points; 95 % [CI: 8.0 to 17.6; p < 0.001; number needed to screen, 8).  Atrial fibrillation lasting 2.5 minutes or longer was present in 28 of 284 patients (9.9 %) in the intervention group, as compared with 7 of 277 (2.5 %) in the control group (absolute difference, 7.4 percentage points; 95 % CI: 3.4 to 11.3; p < 0.001).  By 90 days, oral anti-coagulant therapy had been prescribed for more patients in the intervention group than in the control group (52 of 280 patients [18.6 %] versus 31 of 279 [11.1 %]; absolute difference, 7.5 percentage points; 95 % CI: 1.6 to 13.3; p = 0.01).  The investigators concluded that, among patients with a recent cryptogenic stroke or TIA who were 55 years of age or older, paroxysmal atrial fibrillation was common.  Non-invasive ambulatory ECG monitoring for a target of 30 days significantly improved the detection of atrial fibrillation by a factor of more than 5 and nearly doubled the rate of anti-coagulant treatment, as compared with the standard practice of short-duration ECG monitoring.

An accompanying editorial stated that at least 2 relevant questions remain unanswered (Kamel, 2014).  "First, subclinical atrial fibrillation is clearly not the whole answer to the riddle of cryptogenic stroke. Even after long-term follow-up involving 3 years of continuous rhythm monitoring in the CRYSTAL AF trial, less than one third of the patients had evidence of atrial fibrillation. We need to identify additional sources of embolism and better markers of known stroke mechanisms such as nonobstructive atherosclerosis. Second, we need more evidence to guide therapy for subclinical atrial fibrillation. Randomized trials of antithrombotic therapy have involved patients with a sufficient burden of atrial fibrillation to allow its recognition without prolonged rhythm monitoring. Whether the proven benefit of anticoagulation in this population extends to patients with subclinical atrial fibrillation must be answered in future trials."

The editorialist (Kamel, 2014) continued: "In the meantime, how should the results of the CRYSTAL AF and EMBRACE trials change practice? The weight of current evidence suggests that subclinical atrial fibrillation is a modifiable risk factor for stroke recurrence, and its presence should be thoroughly ruled out in this high-risk population. Therefore, most patients with cryptogenic stroke or transient ischemic attack should undergo at least several weeks of rhythm monitoring. Relatively inexpensive external loop recorders, such as those used in the EMBRACE trial, will probably be cost-effective; the value of more expensive implantable loop recorders is less clear. Furthermore, the detection of subclinical atrial fibrillation in these patients should generally prompt a switch from antiplatelet to anticoagulant therapy. At the least, patients should be followed closely in order to detect progression to clinically apparent atrial fibrillation, in which case the evidence unambiguously supports anticoagulant therapy for the secondary prevention of stroke."

The BIOTRONIK BioMonitor (BIOTRONIK Home Monitoring) is an implantable cardiac monitor. It differs from other implantables as it does not have leads going to the heart. The BioMonitor is suggested to continuously record ECG data when an arrhythmia occurs. An external magnet can also be positioned over the implanted device to record ECG data when symptoms are experienced. 

The mobile patient management system is a monitoring device designed for detection of cardiac arrhythmias. These devices differ from other ECG devices as they may also monitor activity, body fluid status, body temperature posture and respiratory rate. An example of such a device is the BodyGuardian Remote Monitoring System.

The ViSi Mobile Monitoring System is intended for single or multi-parameter vital sign monitoring of adults. It measures ECG (three or five leads), heart rate, respiration rate, noninvasive blood pressure, noninvasive monitoring of oxygen saturation (SpO2), pulse rate and skin temperature.

Self-monitoring ECG technologies, which may be obtained without physician prescription include, but are not limited to, software applications for smartphones and other electronic devices suggested to monitor ECG, heart rate, oxygen saturation, respiratory rate, etc. In addition, there are devices (wireless or non-wireless) such as the Alive Heart and Activity Monitor (Alive Technologies), a wireless health monitoring system, purported to monitor ECG, heart rate and other non-cardiac related indications. These devices may be attached to a finger, ear lobe or other body part.

Biotronik BioMonitor

Ciconte and colleagues (2017) noted that continuous rhythm monitoring is valuable for adequate AF management in the clinical setting.  Subcutaneous leadless ICMs yield an improved AF detection, overcoming the intrinsic limitations of the currently available external recording systems, thus resulting in a more accurate patient treatment.  These investigators evaluated the detection performance of a novel 3-vector ICM device equipped with a dedicated AF algorithm.  A total of 66 patients (86.4 % males; mean age of 60.4 ± 9.4 years) at risk to present AF episodes, having undergone the novel ICM implant (BioMonitor, Biotronik SE&Co. KG, Berlin, Germany), were enrolled.  External 48-hour ECG Holter was performed 4 weeks after the device implantation.  The automatic ICM AF classification was compared with the manual Holter arrhythmia recordings.  Of the overall study population, 63/66 (95.5 %) had analyzable Holter data, 39/63 (62 %) showed at least 1 true AF episode.  All these patients had at least 1 AF episode stored in the ICM.  On Holter monitoring, 24/63 (38 %) patients did not show AF episodes, in 16 of them (16/24, 67 %), the ICM confirmed the absence of AF.  The AF detection sensitivity and positive predictive value (PPV) for episodes' analysis were 95.4 and 76.3 %, respectively.  The authors concluded that continuous monitoring using this novel device, equipped with a dedicated detection algorithm, yielded an accurate and reliable detection of AF episodes.  They stated that the  ICM is a promising tool for tailoring individual AF patient management; further long-term prospective studies are needed to confirm these encouraging results.

The AliveCor Heart Monitor (iPhoneECG)

Chung and Guise (2015) evaluated the feasibility of AliveCor tracings for QTC assessment in patients receiving dofetilide.  A total of 5 patients with persistent AF underwent the 2-handed measurement (mimicks Lead I).  On the ECG, Lead I or II was used.  There was no significant difference between the AliveCor-QTC and ECG-QTC (all ± 20 msec).  The authors concluded that the AliveCor device can be used to monitor the QTC in these patients.  This was a small (n = 5) feasibility study; the clinical role of the AliveCor heart monitor has yet to be established.

Baquero et al (2015) stated that the AliveCor ECG is an FDA-approved ambulatory cardiac rhythm monitor that records a single channel (lead I) ECG rhythm strip using an iPhone.  In the past few years, the use of smartphones and tablets with health related applications has significantly proliferated.  In this initial feasibility trial, these researchers attempted to reproduce the 12-lead ECG using the bipolar arrangement of the AliveCor monitor coupled to smart phone technology.  They used the AliveCor heart monitor coupled with an iPhone cellular phone and the AliveECG application (APP) in 5 individuals.  In these 5 individuals, recordings from both a standard 12-lead ECG and the AliveCor generated 12 lead ECG had the same interpretation.  The authors concluded that the findings of this study demonstrated the feasibility of creating a 12-lead ECG with a smart phone.  They stated that the validity of the recordings would seem to suggest that this technology could become an important useful tool for clinical use; this new hand-held smartphone 12-lead ECG recorder needs further development and validation.

In a pilot study, Muhlestein et al (2015) attempted to gain experience with smartphone ECG prior to designing a larger multi-center study evaluating standard 12-lead ECG compared to smartphone ECG.  A total of 6 patients for whom the hospital STEMI protocol was activated were evaluated with traditional 12-lead ECG followed immediately by a smartphone ECG using right (VnR) and left (VnL) limb leads for precordial grounding.  The AliveCor Heart Monitor was utilized for this study.  All tracings were taken prior to catheterization or immediately after re-vascularization while still in the catheterization laboratory.  The smartphone ECG had excellent correlation with the gold standard 12-lead ECG in all patients; 4 out of 6 tracings were judged to meet STEMI criteria on both modalities as determined by 3 experienced cardiologists, and in the remaining 2, consensus indicated a non-STEMI ECG diagnosis.  No significant difference was noted between VnR and VnL.  The authors concluded that smartphone-based ECG is a promising, developing technology intended to increase availability and speed of electrocardiographic evaluation.  This study confirmed the potential of a smartphone ECG for evaluation of acute ischemia and the feasibility of studying this technology further to define the diagnostic accuracy, limitations and appropriate use of this new technology.

Peritz et al (2015) noted that rapidly detecting dangerous arrhythmias in a symptomatic athlete continues to be an elusive goal.  The use of hand-held smartphone ECG monitors could represent a helpful tool connecting the athletic trainer to the cardiologist.  A total of 6 college athletes presented to their athletic trainers complaining of palpitations during exercise were included in this analysis.  A single-lead ECG was performed using the AliveCor Heart Monitor and sent wirelessly to the Team Cardiologist who confirmed an absence of dangerous arrhythmia.  The authors concluded that the AliveCor monitoring has the potential to enhance evaluation of symptomatic athletes by allowing trainers and team physicians to make diagnosis in real-time and facilitate faster return to play.

Chan and associates (2016) stated that diagnosing AF before ischemic stroke occurs is a priority for stroke prevention in AF.  Smartphone camera-based photo-plethysmographic (PPG) pulse waveform measurement discriminates between different heart rhythms, but its ability to diagnose AF in real-world situations has not been adequately investigated.  These researchers evaluated the diagnostic performance of a stand-alone smartphone PPG application, Cardiio Rhythm, for AF screening in primary care setting.  Patients with hypertension, with diabetes mellitus, and/or aged greater than or equal to 65 years were recruited.  A single-lead ECG was recorded by using the AliveCor heart monitor with tracings reviewed subsequently by 2 cardiologists to provide the reference standard; PPG measurements were performed by using the Cardiio Rhythm smartphone application; AF was diagnosed in 28 (2.76 %) of 1,013 participants.  The diagnostic sensitivity of the Cardiio Rhythm for AF detection was 92.9 % (95 % CI: 77 to 99 %) and was higher than that of the AliveCor automated algorithm (71.4 % [95 % CI: 51 to 87 %]).  The specificities of Cardiio Rhythm and the AliveCor automated algorithm were comparable (97.7 % [95 % CI: 97 to 99 %] versus 99.4 % [95 % CI: 99 to 100 %]).  The PPV of the Cardiio Rhythm was lower than that of the AliveCor automated algorithm (53.1 % [95 % CI: 38 to 67 %] versus 76.9 % [95 % CI: 56 to 91 %]); both had a very high negative predictive value (NPV) (99.8 % [95 % CI: 99 to 100 %] versus 99.2 % [95 % CI: 98 to 100 %]).  The authors concluded that the Cardiio Rhythm smartphone PPG application provided an accurate and reliable means to detect AF in patients at risk of developing AF and has the potential to enable population-based screening for AF.

Desteghe and colleagues (2017) determined the usability, accuracy, and cost-effectiveness of 2 hand-held single-lead ECG devices for AF screening in a hospital population with an increased risk for AF.  Hospitalized patients (n = 445) at cardiological or geriatric wards were screened for AF by 2 hand-held ECG devices (MyDiagnostick and AliveCor).  The performance of the automated algorithm of each device was evaluated against a full 12-lead or 6-lead ECG recording.  All ECGs and monitor tracings were also independently reviewed in a blinded fashion by 2 electrophysiologists.  Time investments by nurses and physicians were tracked and used to estimate cost-effectiveness of different screening strategies.  Hand-held recordings were not possible in 7 and 21.4 % of cardiology and geriatric patients, respectively, because they were not able to hold the devices properly.  Even after the exclusion of patients with an implanted device, sensitivity and specificity of the automated algorithms were sub-optimal (Cardiology: 81.8 and 94.2 %, respectively, for MyDiagnostick; 54.5 and 97.5 %, respectively, for AliveCor; Geriatrics: 89.5 and 95.7 %, respectively, for MyDiagnostick; 78.9 and 97.9 %, respectively, for AliveCor).  A scenario based on automated AliveCor evaluation in patients without AF history and without an implanted device proved to be the most cost-effective method, with a provider cost to identify 1 new AF patient of €193 and €82 at cardiology and geriatrics, respectively.  The cost to detect 1 preventable stroke per year would be €7535 and €1916, respectively (based on average CHA2DS2-VASc of 3.9 ± 2.0 and 5.0 ± 1.5, respectively).  Manual interpretation increases sensitivity, but decreases specificity, doubling the cost per detected patient, but remains cheaper than sole 12-lead ECG screening.  The authors concluded that using AliveCor or MyDiagnostick hand-held recorders requires a structured screening strategy to be effective and cost-effective in a hospital setting.  It must exclude patients with implanted devices and known AF, and requires targeted additional 12-lead ECGs to optimize specificity.  They noted that under these circumstances, the expenses per diagnosed new AF patient and preventable stroke are reasonable.

Chan and colleagues (2017) noted that 2 new devices have been introduced that use automated algorithms to diagnose AF.  One FDA-approved device uses algorithms on a smartphone and dry electrodes that plug into the phone to detect AF (AliveCor Heart Monitor), while the other is in use in Europe and uses an algorithm integrated with an automatic blood pressure device (Microlife WatchBP Office AFIB).  In this study from Hong Kong, a total of 2,052 patients with a mean age of 68 years were evaluated by both devices.  If either diagnosed AF, a 12-lead ECG was performed.  Two cardiologists examined the single-lead ECG generated by the AliveCor device to determine the reference standard cardiac rhythm.  They then calculated the sensitivity and specificity of the devices.  Poor sensitivity could lead to missed diagnoses, whereas poor specificity would lead to the need for unnecessary ECGs to confirm the diagnosis.  The AliveCor device detected 16 of 24 patients with a final diagnosis of AF (67 % sensitivity; 95 % CI: 45 % to 84%) compared with 20 of 24 for the MicroLife device (83 % sensitivity; 95 % CI: 63 % to 95 %).  The AliveCor device had 11 false-positive results (99.5 % specificity) compared with 27 for the Microlife device (98.7 % specificity).

Lown and co-workers (2017) stated that AF is a cause of stroke and a marker of atherosclerosis and of all patients with stroke, around 17 % have AF.  The screening and treatment of AF could prevent about 12 % of all strokes.  Several relatively low-cost devices with good accuracy now exist which can detect AF including WatchBP and AliveCor.  However, they can only measure the ECG or pulse over short time periods.  Inexpensive devices such as heart rate monitors, which are widely available, can measure heart rate for prolonged periods and may have potential in screening for AF.  In a pilot study, these researchers determined the accuracy of AliveCor and WatchBP along with a bespoke algorithm using a heart rate monitor belt (Polar H7) and a wearable RR interval recorder (Firstbeat Bodyguard 2) for detecting AF during a single screening visit in primary care patients.  This is a multi-center case-control diagnostic study comparing the 4 different devices for the detection of AF with a reference standard consisting of a 12-lead ECG in GP surgeries across Hampshire, UK.  These investigators aim to recruit 92 participants with AF and 329 without AF aged 65 years and over.  They will ask participants to rate comfort and overall impression for each device; and will collect qualitative data from participants capturing their experience of using wearable devices in order to evaluate acceptability.  These researchers will collect data from general practitioners to determine their views on AF screening.  The authors concluded that this protocol was approved by the London-City & East Research Ethics Committee in June 2016.  The findings of the trial will be disseminated through peer-reviewed journals, national and international conference presentations and the Atrial Fibrillation Association, UK.  Moreover, these investigators stated that based on the results, they will design a larger clinical trial to examine prolonged AF screening in the community using inexpensive consumer devices.

Tu and colleagues (2017) stated that paroxysmal AF is a common and preventable cause of devastating strokes.  However, currently available monitoring methods, including Holter monitoring, cardiac telemetry and event loop recorders, have drawbacks that restrict their application in the general stroke population.  AliveCor heart monitor, a novel device that embeds miniaturized ECG in a smartphone case coupled with an application to record and diagnose the ECG, has recently been shown to provide an accurate and sensitive single-lead ECG diagnosis of AF.  This device could be used by nurses to record a 30-s ECG instead of manual pulse taking and automatically provide a diagnosis of AF.  These researchers plan to compare the proportion of patients with paroxysmal AF detected by AliveCor ECG monitoring with current standard practice.  Consecutive ischemic stroke and transient ischemic attack patients presenting to participating stroke units without known AF will undergo intermittent AliveCor ECG monitoring administered by nursing staff at the same frequency as the vital observations of pulse and blood pressure until discharge, in addition to the standard testing paradigm of each participating stroke unit to detect paroxysmal AF.  This study will enroll 296 subjects; primary outcome will be proportion of patients with paroxysmal AF detected by AliveCor ECG monitoring compared to 12-lead ECG, 24-h Holter monitoring and cardiac telemetry.  The authors concluded that the use of AliveCor heart monitor as part of routine stroke unit nursing observation has the potential to be an inexpensive non-invasive method to increase paroxysmal AF detection, leading to improvement in stroke secondary prevention.

CardioPatch

Marcelli and colleagues (2017) described the conceptual design and the first prototype implementation of the Multi-Sense CardioPatch, a wearable multi-sensor patch for remote heart monitoring aimed at providing a more detailed and comprehensive heart status diagnostics.  The system integrates multiple sensors in a single patch for detection of both electrical (ECG) and mechanical (Heart Sounds, HS) cardiac activity, in addition to physical activity (PA).  The prototypal system also comprises a microcontroller board with a radio communication unit and it is powered by a Li-Ion rechargeable battery.  Results from preliminary evaluations on healthy subjects have shown that the prototype can successfully measure electro-mechanical cardiac activity, providing useful cardiac indexes.  The authors concluded that the system has potential to improve remote monitoring of cardiac function in chronically diseased patients undergoing home-based cardiac rehabilitation programs.

iHEART/Kardia Mobile

Kardia Mobile is the next generation of trans-telephonic ECG event recorders.

Hickey et al (2016) stated that AF is a major public health problem and is the most common cardiac arrhythmia, affecting an estimated 2.7 million Americans.  The true prevalence of AF is likely under-estimated because episodes are often sporadic; therefore, it is challenging to detect and record an occurrence in a "real world" setting.  To-date, mobile health tools that promote earlier detection and treatment of AF and improvement in self-management behaviors and knowledge have not been evaluated.  This study will be the first to address the problem of AF with a novel approach utilizing advancements in mobile health ECG technology to empower patients to actively engage in their healthcare and to evaluate impact on quality of life and quality-adjusted life years.  Furthermore, sending a daily ECG transmission, coupled with receiving educational and motivational text messages aimed at promoting self-management and a healthy lifestyle may improve the management of chronic cardiovascular conditions (e.g., diabetes, heart failure, and hypertension, etc.).  These researchers are currently conducting a prospective, single-center RCT to evaluate the effectiveness of a mobile health intervention, iPhone® Helping Evaluate Atrial fibrillation Rhythm through Technology (iHEART) versus usual cardiac care.  A total of 300 participants with a recent history of AF will be enrolled.  Participants will be randomized 1:1 to receive the iHEART intervention, receiving an iPhone® equipped with an AliveCor® Mobile ECG and accompanying Kardia application and behavioral altering motivational text messages or usual cardiac care for 6 months.  The authors stated that this will be the first study to investigate the utility of a mobile health intervention in a "real world" setting.  They will evaluate the ability of the iHEART intervention to improve the detection and treatment of recurrent AF and assess the intervention's impact on improving clinical outcomes, quality of life, quality-adjusted life-years and disease-specific knowledge.

Halcox and associates (2017) conducted a randomized controlled trial (RCT) of AF screening using an AliveCor Kardia monitor attached to a WiFi-enabled iPod to obtain ECGs (iECGs) in ambulatory patients.  Patients greater than or equal to 65 years of age with a CHADS-VASc score greater than or equal to 2 free from AF were randomized to the iECG arm or routine care (RC).  iECG participants acquired iECGs twice-weekly over 12 months (plus additional iECGs if symptomatic) onto a secure study server with over-read by an automated AF detection algorithm and by a cardiac physiologist and/or consultant cardiologist.  Time to diagnosis of AF was the primary outcome measure.  The overall cost of the devices, ECG interpretation, and patient management were captured and used to generate the cost per AF diagnosis in iECG patients.  Clinical events and patient attitudes/experience were also evaluated.  These researchers studied 1,001 patients (500 iECG, 501 RC) who were 72.6 ± 5.4 years of age; 534 were women.  Mean CHADS-VASc score was 3.0 (heart failure, 1.4 %; hypertension, 54 %; diabetes mellitus, 30 %; prior stroke/transient ischemic attack, 6.5 %; arterial disease, 15.9 %; all CHADS-VASc risk factors were evenly distributed between groups).  A total of 19 patients in the iECG group were diagnosed with AF over the 12-month study period versus 5 in the RC arm (HR, 3.9; 95 % CI: 1.4 to 10.4; p = 0.007) at a cost per AF diagnosis of $10,780 (£8255).  There was a similar number of stroke/transient ischemic attack/systemic embolic events (6 versus 10, iECG versus RC; HR = 0.61; 95 % CI: 0.22 to 1.69; p = 0.34).  The majority of iECG patients were satisfied with the device, finding it easy to use without restricting activities or causing anxiety.  The authors concluded that screening with twice-weekly single-lead iECG with remote interpretation in ambulatory patients greater than or equal to 65 years of age at increased risk of stroke was significantly more likely to identify incident AF than RC over a 12-month period.  They stated that this approach is also highly acceptable to this group of patients, supporting further evaluation in an appropriately powered, event-driven clinical trial.

Narasimha and colleagues (2018) noted that ambulatory cardiac monitoring devices such as ELRs are often used in the out-patient clinic to evaluate palpitations.  However, ELRs can be bulky and uncomfortable to use, especially in public, at work, or in social situations.  An alternative approach is a smartphone-based ECG recorder/event recorder (Kardia Mobile [KM]), but the comparative diagnostic yield of each approach has not been studied.  In this study, a total of 33 patients with palpitations wore an ELR and carried a KM for a period of 14 to 30 days.  They were instructed to transmit ECGs via KM and also to activate the ELR whenever they had symptoms.  The tracings obtained from both devices were independently analyzed by 2 cardiologists, and the overall arrhythmia yield, as well as patient preference and compliance, were evaluated.  The paired binomial data obtained from both devices were compared using an unconditional test of non-inferiority.  Of the 38 patients enrolled in the study, more patients had a potential diagnosis for their symptoms (i.e., at least 1 symptomatic recording during the entire monitoring period) with KM than with the ELR (KM = 34 [89.5 %] versus ELR = 26 [68.4 %]; χ2  = 5.1, p = 0.024).  In the per protocol analysis, all 33 patients (100 %) had a potential diagnosis using the KM device, which was significantly higher compared to 24 patients (72.2 %) using the ELR (χ2  = 10.4, p = 0.001).  The authors concluded that KM was non-inferior to an ELR for detecting arrhythmias in the out-patient setting.  They stated that the ease of use and portability of this device made it an attractive option for the detection of symptomatic arrhythmias.  This was a small study (n = 33) with a short study duration (14 to 30 days).  These findings need to be validated by well-designed studies.

Pacemaker Event Recorders for Detection of Ventricular Arrhythmias

Sampaio and colleagues (2018) noted that although new pacemakers can register cardiac rhythm, few studies were performed evaluating their accuracy in diagnosing ventricular arrhythmias (VA).  These investigators examined the correlation and agreement between the pacemaker's monitor and the ambulatory Holter in detecting VA.  They studied 129 patients with pacemakers, mean age of 68.6 ± 19.1 years, 54.8 % women.  Once Holter monitoring was connected, the pacemakers' event counters were reset and clocks of both systems were synchronized to register ECG simultaneously.  Pacemakers were programmed to detect the lowest ventricular rate and lowest number of sequential beats allowed in their event monitors.  After 72 hours, Holter and pacemakers records were analyzed; VA was defined in Holter and event monitor respectively as: isolated premature ventricular complexes: "PVC"; pairs: "couplets"; non-sustained ventricular tachycardia (NSVT): "triplets"- 3 beats; "runs"- 4 to 8 or greater than 8 beats, and "HVR"- 3 to 4 beats.  Spearman correlations evaluated whether pacemaker and Holter identified the same parameters.  Intra-class correlation coefficients (ICCs) and respective 95 % CIs were calculated to assess the concordance between methods.  The agreement between both systems was low, except for "triplet" and 3 beats NSVT (ICC = 0.984).  The correlation for more than 10 PVC/hour was moderate (kappa = 0.483).  When the pacemaker was programmed to detect HVR sequences of 3 beats lower than 140 bpm (less than 140/3), the correlation with NSVT was perfect (r = 1) and agreement was also quite high (ICC = 0.800).  The authors concluded that pacemaker's event monitors under-estimated the occurrence of VAs detected by Holter.  They stated that standardization of pacemakers' algorithms is needed before using this function for patient's clinical follow-up.

Appendix

Short-Term High Risk Criteria Which Require Prompt Hospitalization or Intensive Evaluation

• Severe structural or coronary artery disease (heart failure, low LVEF, or previous myocardial infarction)
• Clinical or ECG features suggesting arrhythmic syncope
   
  
  • Syncope during exertion or supine
  • Palpitations at the time of syncope
  • Family history of SCD
  • Non-sustained VT
  • Bifascicular-block (LBBB or RBBB combined with left anterior or left posterior fascicular block) or other intraventricular conduction abnormalities with QRS duration ≥120 ms
  • Inadequate sinus bradycardia (<50 bpm) or sinoartrial block in absence of negative chronotropic medications or physical training
  • Pre-excited QRS complex
  • Prolonged or short QT interval
  • RBBB pattern with ST-elevation in leads V1-V3 (Brugada pattern)
  • Negative T waves in right precordial leads, epsilon waves, and ventricular late potentials suggestive of ARVC
     
• Important co-morbidities
  
  
  • Severe anemia
  • Electrolyte disturbance

Key: ARVC: arrhythmogenic right ventricular cardiomyopathy; bpm: beats per minute; LBBB: left bundle branch block; LVEF: left ventricular ejection fraction; RBBB: right bundle branch block; SCD: sudden cardiac death; VT: ventricular tachycardia.

Source: Task Force for the Diagnosis and Management of Syncope; European Society of Cardiology (ESC); European Heart Rhythm Association (EHRA); Heart Failure Association (HFA); Heart Rhythm Society (HRS), Moya A, Sutton R, Ammirati F, et al. Guidelines for the diagnosis and management of syncope (version 2009). Eur Heart J. 2009;30(21):2631-2671. 

The above policy is based on the following references: