1. Aetna considers external intermittent cardiac event monitors (i.e., external loop recorders) medically necessary for any of the following conditions:

   1. To document an arrhythmia instead of using a Holter monitor or if a Holter monitor (see CPB 019 - Holter Monitors) fails to document a suspected arrhythmia; 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 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.

   External loop recorders are considered experimental and investigational for all other indications.

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) medically necessary for evaluation of recurrent unexplained episodes of presyncope, syncope, 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 nondiagnostic Holter monitor, or symptoms occur infrequently (less frequently than daily) such that the arrhythmia is unlikely to be diagnosed by Holter monitoring.

   MCT has no proven value for other indications.

3. Aetna considers an implantable loop recorder (e.g., Reveal Insertable Loop Recorder by Medtronic, Inc.) medically necessary for evaluation of recurrent unexplained episodes of pre-syncope, syncope, 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. Non-invasive ambulatory monitoring, consisting of either MCT or two 30-day pre-symptom external loop recordings, fails to establish a definitive diagnosis because the symptoms occur so infrequently and unpredictably that the monitoring period may not have been long enough to capture a diagnostic ECG.

   Implantable loop recorders are considered experimental and investigational for all other indications.

   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.

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

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 (see, 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, mentally retarded persons) who cannot 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 (see, 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 minutes of memory.  Cardiac event monitors with expanded memory capabilities have been developed, extending memory from approximately 20 to 30 minutes (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 noninvasive 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. MCT is similar to standard cardiac telemetry used in the hospital setting.

CardioNet (Philadelphia, PA) has developed an MCT device with extended memory, automatic 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 (see CPB 019 - 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 antiarrhythmic drug therapy.

The CardioNet ambulatory ECG arrhythmia detector and alarm is cleared for marketing by the 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, presyncope, 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 percent of MCT subjects compared to 75 percent 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 also evidence to suggest that MCT is superior to autotriggered external loop recorders for diagnosing symptoms thought to be due to a cardiac arrhythmia. Loop recorders with autotrigger 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 autotriggered loop recorders, as this type of recorder was not available at all study sites. However, two of the 17 study sites used looping event recorders with an autotrigger algorithm in all of their randomized patients (Rothman, et al., 2007). Forty-nine subjects, or 16 percent of the randomized population were from these two sites. In a post-hoc analysis of this subgroup of patients, a diagnosis was made in 88 percent of MCT subjects compared to 46% of patients with autotriggered external loop recorders. One possible factor accouting for the poor diagnostic yield of the autotrigger 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 autotrigger 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 workup bias; the study did not describe whether any of the study subjects had ever had previous workups 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 examine the records of 122 consecutive patients evaluated using MCT for palpitations (n = 76), presyncope/syncope (n = 17), or to monitor the effectiveness of antiarrhythmic therapy (n = 29). The investigators reported on the proportion of patients with syncope/presyncope 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 five days per month for six 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 Hearlink 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 two 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 autotrigger 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 U.S. Food and Drug Administration 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 RCT [by Rothman, et al., 2007] (only 16% of patients used this model)."

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:

   • Dynamic electrocardiography (e.g., Holter monitor)

   • Non-attended.

CMS has determined that an ambulatory cardiac monitoring device or service is not covered if it does not fit into these categories.  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."