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MP 2.02.08 Ambulatory Event Monitors and Mobile Cardiac Outpatient Telemetry

Medical Policy    
Original Policy Date
Last Review Status/Date
Reviewed with literature search/10:2013


Our medical policies are designed for informational purposes only and are not an authorization, or an explanation of benefits, or a contract.  Receipt of benefits is subject to satisfaction of all terms and conditions of the coverage.  Medical technology is constantly changing, and we reserve the right to review and update our policies periodically.


There are a wide variety of devices available for outpatient cardiac rhythm monitoring. The primary purpose of these devices is the evaluation of suspected arrhythmias that have not been detected by office- or hospital-based monitoring. These devices differ in the types of monitoring leads used, the duration and continuity of monitoring, the ability to detect arrhythmias without patient intervention, and the mechanism of delivery of the information from patient to clinician.


A brief description of the major categories of devices is given below. There has been a trend in recent years toward using novel technology to increase the efficiency, comfort, and convenience of these devices. These technologic advances include the development of devices that are smaller and more convenient to use, as well as novel ways to rapidly transmit information, such as by use of mobile devices. These advances in technology may present challenges in categorizing new devices.

Some of the newer devices are described below for informational purposes in assigning them to the most relevant category. However, since there may be many devices within each category, a comprehensive description of individual devices is beyond the scope of this review.

Continuous monitoring devices (Holter monitors and similar devices)

Ambulatory Holter electrocardiography (EKG) is a widely used noninvasive test in which EKG is continuously recorded over an extended period of time, typically 24 to 48 hours, to evaluate symptoms suggestive of cardiac arrhythmias, ie, palpitations, dizziness, or syncope. However, Holter monitoring will be ineffective if a patient experiences infrequent symptoms. Therefore, the sensitivity of Holter monitoring is low for detection of arrhythmias that are intermittent.

Continuous monitoring devices with longer recording periods

Some newer devices are continuous monitors that are similar to traditional Holter monitoring in concept, but offer other advantages such as the ability to monitor for longer periods of time.

  • The Zio® Patch system (iRhythm Technologies, Inc., San Francisco, CA) is a long-term continuous monitoring system that is most analogous to a Holter monitor that records and stores information for longer time periods. It is primarily used for asymptomatic monitoring. This system consists of a patch worn over the left pectoral region of the body that records continuously for up to 14 days, while the patient keeps a symptom log. At the end of the recording period, the patient mails back the recorder in a prepaid envelope to a central station and a full report is provided to the physician within a few days.
  • The BodyGuardian Remote Monitoring System™ (Preventice®, Inc., Minneapolis, MN) continuously detects and records a variety of physiologic data including ECG tracing, respiratory rate, and activity level for up to 30 days. The data can be transmitted to the physician’s office via a cellular telephone, and information can be viewed by the patient and physician through the internet.

Noncontinuous monitoring devices (ambulatory event monitors and similar devices)

Ambulatory event monitors (AEMs) were developed to provide longer periods of monitoring by using noncontinuous monitoring. In this technique, the recording device is either worn continuously and activated only when the patient experiences symptoms, or is carried by the patient and applied and activated when symptoms are present. The recorded EKGs are then stored for future analysis or transmitted by telephone to a receiving station, eg, a doctor's office; hospital; or cardiac-monitoring service, where the EKGs can then be analyzed. AEMs can be used for extended periods of time, typically up to 1 month or until the patient experiences symptoms. Since the EKGs are recorded only during symptoms, there is good correlation with any underlying arrhythmia. Conversely, if no EKG abnormality is noted, a noncardiac etiology of the patient's symptoms can be sought. Several different types of AEMs are available:

Noncontinuous devices with memory

These devices are carried by the patient and applied to the precordial area via nongel electrodes when the symptoms are occurring or, alternatively, a recording device may be worn on the wrist and then activated when symptoms are present. The limitation of these devices is that an arrhythmia of very short duration would be difficult to record. In addition, noncontinuous devices require reasonable dexterity on the part of the patient to apply the device correctly during a symptomatic period. This is a particular limitation if the patient is incapacitated during symptomatic periods.

  • The Zio® Event Card (iRhythm Technologies, Inc., San Francisco, CA) is a noncontinuous real-time recording device that can be worn up to 30 days. This device can be worn comfortably under clothing (including during sleep), as it weighs less than 2 ounces and is similar in size to a standard credit card. Upon activation by the patient, the card is able to record the previous 45 seconds of electrocardiography (ECG) activity into memory plus the first 15 seconds after the button is pushed. This is made possible because this device continuously scans for ECG activity but only records upon symptom activation. After the device is activated, the patient is responsible for calling the iRhythm National Clinical Center (NCCC), which then instructs the patient on sending the event over the phone line.
  • The REKA E100™ system is a noncontinuous single-lead cardiac event monitor. This device is the size of a hockey puck and weighs no more than a few ounces. There are 2 options, depending on the patient’s circulation: (1) a zero-lead device that is separate from the body and may be carried in a purse or coat pocket; or if a patient’s circulation is determined to be inadequate, (2) a single electrode lead that the patient connects to the device at the time of an event. The zero-lead device records an event by patient activation and can record and store up to 2000 readings. The patient has the option of sending stored event information to the physician across a free-of-charge phone app or the Internet in their computer. Internet transmission requires one of the following systems: Android, Blackberry, iPhone 3, 3S, 4, and 4S, iPad, iPod Touch® Microsoft, or Windows.

Continuous "memory loop" devices

These devices are able to continuously store a single channel of EKG data in a refreshed memory. If the patient activates the device, the EKG is then recorded from the memory loop for the preceding 30 to 90 seconds and for the next minute or so. Therefore, these types of devices permit recording of the onset of arrhythmias and/or transient or incapacitating events . They obviously must be worn continuously.

Implantable continuous “memory loop” devices

An implantable loop recorder device is inserted just under the patient’s skin in the chest area during an outpatient surgical procedure. When symptoms are felt, the patient places a hand-held activator over the recorder to activate the storage of cardiac rhythms. This device can be used for more than 1 year. The Reveal® Insertable Loop Recorder (Medtronic) is an implantable memory loop device recently approved by the U.S. Food and Drug Administration (FDA).

Autotrigger devices

All of the previously described devices require activation by the patient. More recently, autotriggering technology has become available, which can be adapted to memory loop devices. For example, event monitors can be programmed to detect heart rates greater than 165 beats per minute, less than 40 beats per minute, or an asystole of greater than 3 seconds.

Implantable continuous “memory loop” devices with autotrigger

These devices combine the long-term monitoring available with implantable devices with the autotriggers seen on newer event monitors. These devices contain algorithms that are programmed to detect heart rates exceeding an upper or lower limit, asystole of greater than 3 seconds. They typically contain other autotriggers, such as a variable RR interval seen with atrial fibrillation.

Mobile cardiac outpatient telemetry

Ambulatory event monitors store the recorded data, which are ultimately transmitted either to a physician’s office or to a central recording station. In contrast, outpatient cardiac telemetry provides real-time monitoring and analysis. For example, CardioNet® Inc. (Conshohocken, PA) offers mobile cardiac outpatient telemetry. In this system, the patient wears a 3-lead sensor, which constantly communicates with the CardioNet monitor, a lightweight unit that can be carried in a pocket or a purse. When an arrhythmia is detected according to preset parameters, the EKG is automatically transmitted to a central CardioNet service center, where the EKG is immediately interpreted, with results sent to the referring physician. The referring physician can request the level and timing of response, ranging from daily reports to stat results. Other systems for outpatient cardiac telemetry include the HEARTLink II™ system (Cardiac Telecom Corp.), the Vital Signs Transmitter (VST™, Biowatch Medical, Columbia, SC), and the LifeStar™ Ambulatory Cardiac Telemetry (ACT) system (Card Guard Scientific Survival Ltd., Israel). The CardioNet system has a built-in cellular telephone that automatically transmits signals when the patient is away from home.

  • The VectraplexECG™ System is a real-time continuous Mobile Cardiac Outpatient Telemetry device to measure ischemic ECG changes that can be indicative of a myocardial infarction (MI). This device utilizes the Internet to communicate real-time ECG changes to the physician. The patient is hooked up to a mini-tablet by either 5 electrodes, which communicate 15-lead ECG data, or 10 electrodes that communicate 12-lead ECG data. While this system is primarily intended to monitor for ischemia, the continuous ECG monitoring would presumably detect rhythm disturbances, as well as ischemic changes. 


The use of patient-activated or auto-activated external ambulatory event monitors may be considered medically necessary as a diagnostic alternative to Holter monitoring in the following situations:

  • Patients who experience infrequent symptoms (less frequently than every 48 hours) suggestive of cardiac arrhythmias (ie, palpitations, dizziness, presyncope, or syncope).
  • Patients with atrial fibrillation who have been treated with catheter ablation, and in whom discontinuation of systemic anticoagulation is being considered.

The use of implantable ambulatory event monitors, either patient-activated or auto-activated, may be considered medically necessary only in the small subset of patients who experience recurrent symptoms so infrequently that a prior trial of other external ambulatory event monitors has been unsuccessful.

Outpatient cardiac telemetry (also known as mobile cardiac outpatient telemetry or MCOT) as a diagnostic alternative in patients who experience infrequent symptoms (less frequently than every 48 hours) suggestive of cardiac arrhythmias (ie, palpitations, dizziness, presyncope, or syncope) is expected to result in outcomes that are equivalent to alternatives such as autotrigger devices, but may be more costly than alternatives. In this situation, the more costly alternative may be considerednot medically necessary, and the least costly alternative may be considered medically necessary (See Policy Guidelines, and Benefit Application sections)

Continuous ambulatory monitors that record and store information for periods longer than 48 hours are consideredinvestigational.

Other uses of ambulatory event monitors, including outpatient cardiac telemetry, are considered investigational, including but not limited to monitoring effectiveness of antiarrhythmic medications, for patients with cryptogenic stroke, and detection of myocardial ischemia by detecting ST segment changes.

Policy Guidelines

Based on currently available evidence, health outcomes for MCOT and for alternative treatments appear to be equivalent. When outcomes are expected to be equivalent, the least costly alternative provision may be considered in determining medical necessity. When it is determined that a strategy using MCOT is more costly than one using alternatives (as determined by product pricing, provider charges, and/or other mechanisms), then MCOT may be considered not medically necessary using the Medical Policy Reference Manual definition of medical necessity.

The implantation and removal of an insertable loop recorder are coded as follows:

33282: Implantation of patient-activated cardiac event recorder

33284: Removal of an implantable, patient-activated cardiac event recorder

The interpretation of the EKGs recorded with ambulatory event monitors (AEMs) may be coded as follows:

93268: External patient and, when performed, auto activated electrocardiographic rhythm derived event recording with symptom-related memory loop with remote download capability up to 30 days, 24-hour attended monitoring; includes transmission, physician review and interpretation

The above CPT code represents a bundled CPT code including all components of AEM monitoring, including EKG analysis of all the recorded strips during a 30-day period.

Other CPT codes that can be used for AEM monitoring represent unbundling of the 93268 code. For example, CPT code 93270 describes the connection, recording and disconnection of an external device; CPT code 93271 describes the transmission download and analysis; and 93272 describes the physician review and interpretation of the EKG strips. AEM monitoring services may supply the monitoring, receipt of transmissions and analysis of the EKGs (ie, CPT codes 93271 and 93272), but the provider supplies the hook-up and disconnection of the device (ie, CPT code 93270). If this is the case, the unbundled codes may be used. It should also be noted that CPT code 93272 (physician review and interpretation) applies to all EKGs transmitted during a 30-day period; therefore, billing for each individual transmitted strip is not warranted.

Effective January 1, 2009, there are specific CPT codes for mobile outpatient cardiac telemetry:

93228: External mobile cardiovascular telemetry with electrocardiographic recording, concurrent computerized real-time data analysis and greater than 24 hours of accessible ECG data storage (retrievable with query) with ECG triggered and patient selected events transmitted to a remote attended surveillance center for up to 30 days; physician review and interpretation with report

93229 ; technical support for connection and patient instructions for use, attended surveillance, analysis and physician prescribed transmission of daily and emergent data reports.

Both of these codes can only be reported once per 30 days of service.

Effective in 2012, category III CPT codes were added for devices with longer recording capabilities:

0295T External electrocardiographic recording for more than 48 hours up to 21 days by continuous rhythm recording and storage; includes recording, scanning analysis with report, review and interpretation

0296T ; recording (includes connection and initial recording)

0297T ; scanning analysis with report

0298T ; review and interpretation

Benefit Application

BlueCard/National Account Issues

Plans may consider requiring the use of CPT code 93268, when possible, to avoid unbundling of services. However, aside from the hook-up and disconnection of the device, which is frequently performed by the provider, the actual monitoring and analysis of the electrocardiography (EKG) are frequently performed by a monitoring service. If this is the case, the various components of the ambulatory event monitors (AEMs) will be unbundled.

Because use of mobile cardiac outpatient telemetry (MCOT) is generally more costly than alternatives such as the autotrigger device, but has not been shown to lead to improved outcomes compared to those alternatives, it is considered not medically necessary using the Medical Policy Reference Manual definition of medical necessity.

For contracts that do not use this definition of medical necessity, other contract provisions may apply. For example, benefit or contract language describing the "least costly alternative" may also be applicable for this choice of testing.


Ambulatory event monitors (AEMs) are a well-established technology that are most typically used to evaluate episodes of cardiac symptoms (palpitations, dizziness, syncope), which, due to their infrequency, would escape detection on a standard 24- to 48-hour Holter monitor. Other proposed uses include monitoring the efficacy of antiarrhythmic therapy and evaluating ST segment changes as an indication of myocardial ischemia (MI). However, evidence is inadequate to validate these uses of AEMs. Although serial electrocardiography (EKG) monitoring has often been used to guide antiarrhythmic therapy in patients with symptomatic sustained ventricular arrhythmias or survivors of near sudden cardiac death, (1) it is not known what level of reduction of arrhythmic events constitutes successful drug therapy. Furthermore, the patient’s cardiac activity must be evaluated before and during treatment, such that the patient can serve as his or her own control. The routine monitoring of asymptomatic patients after MI is also controversial, especially after the Cardiac Arrhythmia Suppression Trial (CAST) showed that patients treated with encainide or flecainide actually had a higher mortality. While Holter monitoring has been used to detect ST segment changes, it is unclear whether ST segment changes can be reliably detected by an AEM. The interpretation of ST segment change is limited by instability of the isoelectric line, which is in turn dependent on meticulous attention to skin preparation, electrode attachment, and measures to reduce cable movement.

Hoefman et al.(2) published a systematic review on diagnostic tools for detecting cardiac arrhythmias. This analysis included studies of patients presenting with palpitations and compared the yield of remote monitoring for several classes of devices: Holter monitors; patient-activated event recorders; autotriggered event recorders; and implantable loop recorders. The yield varied among devices, with the autotrigger devices offering the highest range of detection (72-80%), followed by the patient-activated devices (17-75%), and Holter monitors (33-35%). No combined analysis was performed due to heterogeneity in patient population and study design. Limitations in the evidence base precluded any specific recommendations on selection of devices. The authors concluded that the choice of device should be driven largely by the presence, type, and frequency of symptoms experienced by each individual patient.

Continuous Monitors With Longer Recording Periods

Newer devices are available that record cardiac rhythms continuously, but for longer periods of time than traditional Holter monitors. For example, the Zio® Patch continuously records and stores information for up to 2 weeks. In addition to recording information for longer periods of time, this device uses “near-field” recording electrodes that differ from most other devices.

Tuakhia et al. published a study in 2013 evaluating the diagnostic yield of the Zio Patch.(3) Data from the manufacturer was used to identify 26,751 first-time users of the device. The most common clinical indications were palpitations (40.3%), atrial fibrillation (24.3%) and syncope (15.1%). The mean duration of use was 7.6±3.6 days, and 95.9% of patients wore the device for more than 48 hours. At least one episode of arrhythmia was detected in 16,142 patients (60.3%). The authors compared the detection rate in the first 48 hours with the detection rate over the entire time period that the device was worn. 70.1% of patients had their arrhythmia detected within the first 48 hours, and 29.9% had their first arrhythmia detected after the first 48 hours. The overall yield was significantly higher when comparing the total monitored period with the first 48 hours (62.2% vs 43.9%, p<0.0001). These data confirm previous studies that have shown that a substantial proportion of arrhythmias in symptomatic patients can be detected with a 48-hour period of monitoring and that longer monitoring periods increase the detection rate.

Autotriggered Event Monitors and Loop Recorders

Autotrigger loop recorders have become a part of the standard diagnostic approach to patients who have infrequent symptoms that are thought likely to be due to arrhythmias. Therefore, this is the test to which newer technologies should be compared.

Several studies, including an analysis of a database of 100,000 patients, compared the diagnostic yield of automatic and patient-activated arrhythmia recordings and reported an improved yield with autotriggering devices.(4-6) One comparative study of 50 patients noted that auto-activation may result in a large number of inappropriately stored events.(7) The policy statement does not distinguish whether the device used is auto- or patient-activated.

Implantable autotrigger loop recorders have also been developed that are specifically geared toward detection of atrial fibrillation through the use of atrial fibrillation detection algorithms. Hindricks et al.(8) evaluated the accuracy of an implantable autotriggered loop recorder in 247 patients at high risk for paroxysmal atrial fibrillation. All patients underwent simultaneous 46-hour continuous Holter monitoring, and the authors calculated the performance characteristics of the loop recorder using physician-interpreted Holter monitoring as the gold standard. The sensitivity of the loop recorder for detecting atrial fibrillation episodes of 2 minutes or more in duration was 88.2%, rising to 92.1% for episodes of 6 minutes or more. Atrial fibrillation was falsely identified by the loop recorder in 19 of 130 patients who did not have atrial fibrillation on Holter monitoring, for a false-positive rate of 15%. The atrial fibrillation burden was accurately measured by the loop recorder, with the mean absolute difference between the loop recorder and Holter monitor of 1.4±6.4%.

Hanke et al.(9) compared an implantable autotrigger device with 24-hour Holter monitoring done at 3-month intervals in 45 patients who had undergone surgical ablation for atrial fibrillation.(9) After a mean follow-up of 8.3 months, the implantable loop recorder identified atrial fibrillation in 19 patients (42%) in whom Holter monitoring recorded sinus rhythm.

One small RCT was identified that compared the use of an implantable loop recorder with conventional follow-up in 78 patients with a first episode of syncope. (10) A significant number of patients had cardiomyopathy (23%), atrial fibrillation (15.4%), and/or bundle branch block on electrocardiography (ECG, 58%). Mean follow-up time was 27 months. A total of 21 patients (27%) had at least one arrhythmia detected, with a significant difference in detection rate for the implantable loop recorder group (36.6%) compared to the conventional follow-up group (10.8%, p=0.02).

The most recent generation of event recorders has incorporated transmission using cellular phone technology.(11,12) These devices incorporate a cell phone into the event monitor, allowing patients or autotrigger to transmit data directly from the device. This modification is intended to simplify the transmission of data, thus minimizing the proportion of transmissions that are not successful. Leshem-Rubinow et al. performed an observational study of 604 patients with palpitations, presyncope, and/or chest pain. This study demonstrated that the Cardio R® device (SHL-Medical, Tel Aviv, Israel) was able to efficiently diagnose and transmit heart rhythm information. Of 604 patients, a rhythm disturbance that could account for symptoms was found in 49% of cases. The information was transmitted within 7 minutes in 93% of cases.

Mobile Outpatient Cardiac Telemetry

The published literature regarding outpatient cardiac telemetry was reviewed, with a specific focus on whether outpatient cardiac telemetry was associated with incremental benefit compared to the use of ambulatory event monitors. Of specific interest was the benefit of real-time monitoring in an ambulatory population, presumably considered to be at a lower level of risk from significant arrhythmia such that an electrophysiologic study or inpatient telemetry was not required.

A number of uncontrolled case series report on outcomes of mobile cardiac outpatient telemetry (MCOT).(13-16) One such published study described the outcomes of a consecutive case series of 100 patients.(13) Patients with a variety of symptoms were included, including, most commonly, palpitations (47%), dizziness (24%), or syncope (19%), as well as efficacy of drug treatment (25%). Clinically significant arrhythmias were detected in 51% of patients, but half of these patients were asymptomatic. The authors comment that the automatic detection results in an increased diagnostic yield, but there was no discussion of its unique feature, ie, the real-time analysis, transmission, and notification of arrhythmia. In another uncontrolled case series, Tayal et al. reported on a retrospective analysis of patients with cryptogenic stroke, who had not been diagnosed with atrial fibrillation by standard monitoring.(16) In this study, 13 of 56 patients (23%) with cryptogenic stroke were found to have atrial fibrillation with MCOT. Twenty-seven asymptomatic atrial fibrillation episodes were detected in the 13 patients, 23 of these were shorter than 30 seconds in duration.

One randomized controlled trial (RCT) was identified that compared MCOT to standard event monitors.(17) This study involved 305 patients who were randomly assigned to the LOOP recorder or MCOT and who were monitored for up to 30 days. The unblinded study enrolled patients at 17 centers; those enrolled were patients for whom the investigators had a strong suspicion of an arrhythmic cause of symptoms including those with symptoms of syncope, presyncope, or severe palpitations occurring less frequently than once per 24 hours and a nondiagnostic 24-hour Holter or telemetry monitor within the prior 45 days. Test results were read in a blinded fashion by an electrophysiologist. The majority of patients in the control group had a patient-triggered event monitor. Only a subset of patients (n=50) had autotrigger devices, thus precluding a comparison between MCOT and autotrigger devices.

A diagnostic endpoint (confirmation/exclusion of arrhythmic cause of symptoms) was found in 88% of MCOT patients and in 75% of LOOP patients (p=0.008). The difference in rates was primarily due to detection of asymptomatic (not associated with simultaneous symptoms) arrhythmias in the MCOT group, symptoms consisting of rapid atrial fibrillation and/or flutter (15 patients vs 1 patient) and ventricular tachycardia defined as more than 3 beats and rate greater than 100 (14 patients vs. 2 patients). These were thought to be clinically significant rhythm disturbances and the likely causes of the patients’ symptoms. The paper does not comment on the clinical impact (changes in management) of these findings in patients for whom the rhythm disturbance did not occur simultaneously with symptoms. In this study, the median time to diagnosis in the total study population was 7 days in the MCOT group and 9 days in the LOOP group. Kadish et al.(18) evaluated the frequency with which events transmitted by MCOT represented emergent arrhythmias, thereby indirectly assessing the clinical utility of real-time outpatient monitoring. A total of 26,438 patients who had undergone MCOT during a 9-month period were retrospectively examined. Of these patients, 21% (5,459) had an arrhythmic event requiring physician notification, and 1% (260) had an event that could be considered potentially emergent. These potentially emergent events included 120 patients with wide-complex tachycardia, 100 patients with sinus pauses 6 seconds or longer, and 42 with sustained bradycardia at less than 30 beats per minute.

Patients with atrial fibrillation treated with catheter ablation

Many patients with atrial fibrillation treated with catheter ablation are on long-term anticoagulation, and all patients treated with ablation are given anticoagulation for up to 3 months postprocedure. In patients with an apparently successful ablation who do not show signs or symptoms of recurrent atrial fibrillation at time periods longer than 3 months postablation, the decision on whether to continue treatment with anticoagulants needs to be made. Studies have demonstrated that late recurrences are not uncommon following ablation and that these recurrent episodes are often asymptomatic.(19,20) In addition, the presence of recurrent episodes of atrial fibrillation is a predictor of future thromboembolic events. In one of the larger observational study of 565 patients followed postablation, the 2 major predictors of thromboembolism were the CHADS(2) score and the presence of recurrent episodes of atrial fibrillation.(21)

Several other observational studies have followed patients who stopped anticoagulation after an evaluation that included ambulatory monitoring was negative for recurrent episodes. These patients appear to have a low subsequent rate of thromboembolic events. In one such study of 3,355 patients from 5 clinical centers,(22) 2692 discontinued anticoagulation at 3 to 6 months following ablation. During a mean follow-up of 28 months, 2 patients (0.07%) who were off anticoagulation experienced an ischemic stroke. This rate was not significantly different from the rate of stroke in patients who continued anticoagulation (0.45%). The rate of major hemorrhage was lower for patients who were off anticoagulation compared to those who continued (2 vs 0.04%, respectively; p<0.001).

This evidence makes a strong indirect argument that monitoring for asymptomatic episodes of atrial fibrillation by use of ambulatory event monitors will lead to changes in management of long-term anticoagulation. These changes in management based on ambulatory monitoring are likely to lead to improved outcomes.

Patients with cryptogenic stroke

Patients with cryptogenic stroke are often monitored for the presence of atrial fibrillation, since atrial fibrillation is estimated to be the cause of cryptogenic stroke in more than 10% of patients.(23) Approximately 5% of patients with cryptogenic stroke will have atrial fibrillation diagnosed on ECG and/or telemetry monitoring in the hospital. The use of continuous telemetry monitory has been compared to Holter monitoring for patients hospitalized for stroke or transient ischemic attack (TIA); these results are inconclusive as to which is the preferred method.(24,25) Longer-term ambulatory event monitoring will identify additional patients with asymptomatic episodes, with rates of detection reported in the literature for an estimated 6-26% of patients.(23,26,27) Many of these asymptomatic episodes of atrial fibrillation are brief and the relationship to the preceding stroke uncertain, as there are other potential causes of asymptomatic stroke.

There were two trials identified that evaluated ambulatory monitoring in patients with cryptogenic stroke. One small RCT randomized 40 patients with cryptogenic ischemic stroke or high-risk TIA to usual care or 21 days of mobile cardiac outpatient telemetry (MCOT).(28) There were no cases of atrial fibrillation detected in either group. Two patients in the MCOT group had nonsustained ventricular tachycardia detected, which was of uncertain clinical significance in relation to their stroke.

One controlled trial in the outpatient setting was identified, this study compared 7-day Holter monitoring with an implantable loop recorder.(29) A total of 60 patients with an acute cryptogenic stroke that was consistent with an embolic event were included. All patients received 7-day Holter monitoring as well as an implantable cardiac monitor (ICM). Patients were monitored with the ICM for a minimum of one year, or until an episode of atrial fibrillation was detected. A total of 10 patients (17%; 95% confidence interval [CI], 7 to 26%) had atrial fibrillation detected by ICM compared to 1 patient (1.7%; 95% CI, 0 to 5%) who had atrial fibrillation detected by Holter monitor (p<0.001 for between-group comparison of detection rate). The average time to detection with ICM was 64 days (range, 1-556 days). All patients who had atrial fibrillation detected were treated with anticoagulation, and there were no recurrent strokes in either group.

Section Summary

The evidence on the use of ambulatory event monitors in cryptogenic stroke is not sufficient to conclude that health outcomes are improved. Longer periods of monitoring will pick up additional episodes of atrial fibrillation in this patient group. However, the clinical significance of these findings is not certain, especially when brief periods of atrial fibrillation are detected, and/or the time interval between the stroke and detection of atrial fibrillation is long. Initiating anticoagulation in these patients has an accompanying risk of bleeding, so that the benefit/risk ratio needs to be better defined. An ongoing randomized controlled trial (RCT), the CRYSTAL-AF study, is evaluating whether long-term monitoring of patients with cryptogenic stroke leads to changes in anticoagulant management and/or improved outcomes for patients with cryptogenic stroke.(30)

Clinical Input Received through Physician Specialty Societies and Academic Medical Centers

In response to requests, input was received from 1 physician specialty society (1 review) and 4 academic medical centers (5 reviews) while this policy was under review in 2009. While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted. There were differences among reviewers regarding outpatient cardiac telemetry, with some reviewers concluding it had a role in certain subsets of patients; for example, in those with sporadic atrial fibrillation. Other reviewers commented that the value of this technology should be considered in both providing a diagnosis and in making treatment decisions. At times, excluding arrhythmia as a cause of a patient’s symptoms is an important finding.


A number of studies have indicated that autotrigger event monitors detect additional episodes of arrhythmias compared to Holter monitoring or patient-triggered devices. This evidence has led to the acceptance of autotrigger event monitors as the gold standard for detecting arrhythmias that occur infrequently. There is also evidence that autotrigger devices can pick up asymptomatic episodes of atrial fibrillation in patients treated with catheter ablation and that identifying asymptomatic episodes may lead to modifications in treatment. For patients with cryptogenic stroke, longer monitoring periods will detect additional episodes of atrial fibrillation, but the evidence is not sufficient to conclude that outcomes are improved.

Newer continuous monitoring devices are available that use novel technology and record information for longer periods than a Holter monitor, eg, up to 2 weeks. There is a lack of evidence on the quality of recording from these devices, and on the detection rate for cardiac arrhythmias. Due to a lack of evidence, these continuous monitoring devices that record for longer time periods are considered investigational.

Mobile cardiac outpatient telemetry (MCOT) is another option for long-term cardiac monitoring. The current evidence on MCOT establishes that it does record cardiac electric signals, without patient activation, for subsequent analysis. Currently, the literature does not provide any adequate comparative data for MCOT compared to the autotrigger device. One retrospective, uncontrolled study reported that only a small minority of events (1%) detected by MCOT were potentially emergent. None of the available studies have clearly shown an improvement in clinical utility as a result of using MCOT. Further studies are needed to compare MCOT with the autotrigger loop recorder in order to determine whether the faster response possible with real-time monitoring leads to improved outcomes.

Thus, at the present time, outcomes from use of a MCOT are expected to be equivalent to outcomes from use of autotrigger or other types of devices. As a result, in situations where MCOT is more expensive than alternate devices such as the autotrigger device, MCOT is considered not medically necessary.

Practice Guidelines and Position Statements

In 1999, the American College of Cardiology (ACC) in conjunction with the American Heart Association (AHA) published guidelines for the use of ambulatory electrocardiography.(31) These guidelines did not make an explicit distinction between continuous (ie, Holter monitor) and intermittent (ie, ambulatory event monitor) monitoring. Regarding the effectiveness of antiarrhythmic therapy, the ACC guidelines list one Class I* indication: “To assess antiarrhythmic drug response in individuals in whom baseline frequency of arrhythmia has been well characterized as reproducible and of sufficient frequency to permit analysis.” The guidelines do not specify whether Holter monitoring or AEMs are most likely to be used. However, the accompanying text notes that intermittent monitoring may be used to confirm the presence of an arrhythmia during symptoms. This indication is addressed in the first policy statement above, ie, evaluation of symptomatic patients. There were no Class I indications for detection of myocardial ischemia. In addition, there were no Class I indications for ambulatory monitoring to assess risk for future cardiac events in patients without symptoms of arrhythmia. This latter category would suggest that routine monitoring of patients after MI to detect nonsustained ventricular tachycardia as a risk factor for sudden cardiac death is not routinely recommended. As noted in a review article by Zimetbaum and Josephson,(32) there is a paucity of data to document the impact on the final health outcomes, and, furthermore, it is not clear at what point after a myocardial infarction such monitoring would be optimal.

A consensus document on catheter and surgical ablation for atrial fibrillation was published in 2012.(33) This document did not contain formal clinical practice guidelines, but provided general recommendations based on literature review and expert consensus. The use of AEMs postablation was addressed in two sections of the document. First, in the section discussing the use of anticoagulation following ablation, the following statement was made:

  • Patients in whom discontinuation of systemic anticoagulation is being considered should consider undergoing continuous ECG monitoring to screen for asymptomatic AF/AFL/AT.

In the section of the document dealing with postoperative rhythm monitoring of patients who are postablation the following statements were made:

  • ECGs should be obtained at all follow-up visits.
  • More intense monitoring should be mainly driven by the clinical impact of AF [atrial fibrillation] detection with strict monitoring being necessary (eg, in patients with thromboembolic risk factors for determining the adequate anticoagulation approach).
  • Frequent ECG recording using a manually activated event recorder and counseling patients to take their pulse to monitor for irregularity may serve as initial screening tools for asymptomatic AF episodes.
  • A 1- to 7-day Holter monitor is an effective way to identify frequent asymptomatic recurrences of AF.
  • A 4-week autotrigger event monitor, mobile cardiac outpatient telemetry system, or implantable subcutaneous monitor may identify less frequent AF.


  1. DiMarco JP, Philbrick JT. Use of ambulatory electrocardiographic (Holter) monitoring. Ann Intern Med 1990; 113(1):53-68.
  2. Hoefman E, Bindels PJ, van Weert HC. Efficacy of diagnostic tools for detecting cardiac arrhythmias: systematic literature search. Neth Heart J 2010; 18(11):543-51.
  3. Turakhia MP, Hoang DD, Zimetbaum P et al. Diagnostic utility of a novel leadless arrhythmia monitoring device. Am J Cardiol 2013; 112(4):520-4.
  4. Balmelli N, Naegeli B, Bertel O. Diagnostic yield of automatic and patient-triggered ambulatory cardiac event recording in the evaluation of patients with palpitations, dizziness, or syncope. Clin Cardiol 2003; 26(4):173-6.
  5. Ermis C, Zhu AX, Pham S et al. Comparison of automatic and patient-activated arrhythmia recordings by implantable loop recorders in the evaluation of syncope. Am J Cardiol 2003; 92(7):815-9.
  6. Reiffel JA, Schwarzberg R, Murry M. Comparison of autotriggered memory loop recorders versus standard loop recorders versus 24-hour Holter monitors for arrhythmia detection. Am J Cardiol 2005; 95(9):1055-9.
  7. Ng E, Stafford PJ, Ng GA. Arrhythmia detection by patient and auto-activation in implantable loop recorders. J Interv Card Electrophysiol 2004; 10(2):147-52.
  8. Hindricks G, Pokushalov E, Urban L et al. Performance of a new leadless implantable cardiac monitor in detecting and quantifying atrial fibrillation: Results of the XPECT trial. Circ Arrhythm Electrophysiol 2010; 3(2):141-7.
  9. Hanke T, Charitos EI, Stierle U et al. Twenty-four-hour holter monitor follow-up does not provide accurate heart rhythm status after surgical atrial fibrillation ablation therapy: up to 12 months experience with a novel permanently implantable heart rhythm monitor device. Circulation 2009; 120(11 Suppl):S177-84.
  10. Da Costa A, Defaye P, Romeyer-Bouchard C et al. Clinical impact of the implantable loop recorder in patients with isolated syncope, bundle branch block and negative workup: a randomized multicentre prospective study. Arch Cardiovasc Dis 2013; 106(3):146-54.
  11. Leshem-Rubinow E, Berger M, Shacham J et al. New real-time loop recorder diagnosis of symptomatic arrhythmia via telemedicine. Clin Cardiol 2011; 34(7):420-5.
  12. Sankari Z, Adeli H. HeartSaver: a mobile cardiac monitoring system for auto-detection of atrial fibrillation, myocardial infarction, and atrio-ventricular block. Comput Biol Med 2011; 41(4):211-20.
  13. Joshi AK, Kowey PR, Prystowsky EN et al. First experience with a Mobile Cardiac Outpatient Telemetry (MCOT) system for the diagnosis and management of cardiac arrhythmia. Am J Cardiol 2005; 95(7):878-81.
  14. Olson JA, Fouts AM, Padanilam BJ et al. Utility of mobile cardiac outpatient telemetry for the diagnosis of palpitations, presyncope, syncope, and the assessment of therapy efficacy. J Cardiovasc Electrophysiol 2007; 18(5):473-7.
  15. Saarel EV, Doratotaj S, Sterba R. Initial experience with novel mobile cardiac outpatient telemetry for children and adolescents with suspected arrhythmia. Congenital heart disease 2008; 3(1):33-8.
  16. Tayal AH, Tian M, Kelly KM et al. Atrial fibrillation detected by mobile cardiac outpatient telemetry in cryptogenic TIA or stroke. Neurology 2008; 71(21):1696-701.
  17. Rothman SA, Laughlin JC, Seltzer J et al. The diagnosis of cardiac arrhythmias: a prospective multi-center randomized study comparing mobile cardiac outpatient telemetry versus standard loop event monitoring. J Cardiovasc Electrophysiol 2007; 18(3):241-7.
  18. Kadish AH, Reiffel JA, Clauser J et al. Frequency of serious arrhythmias detected with ambulatory cardiac telemetry. Am J Cardiol 2010; 105(9):1313-6.
  19. Dagres N, Kottkamp H, Piorkowski C et al.:Influence of the duration of Holter monitoring on the detection of arrhythmia recurrences after catheter ablation of atrial fibrillation: implications for patient follow-up. Int J Cardiol 2010; 139(3):305-6.
  20. Pokushalov E, Romanov A, Corbucci G et al. Ablation of paroxysmal and persistent atrial fibrillation: 1-year follow-up through continuous subcutaneous monitoring. J Cardiovasc Electrophysiol 2011; 22(4):369-75.
  21. Chao TF, Lin YJ, Tsao HM et al. CHADS(2) and CHA(2)DS(2)-VASc scores in the prediction of clinical outcomes in patients with atrial fibrillation after catheter ablation. J Am Coll Cardiol 2011; 58(23):2380-5.
  22. Themistoclakis S, Corrado A, Marchlinski FE et al. The risk of thromboembolism and need for oral anticoagulation after successful atrial fibrillation ablation. J Am Coll Cardiol 2010; 55(8):735-43.
  23. Mittal S, Movsowitz C, Steinberg JS. Ambulatory external electrocardiographic monitoring: focus on atrial fibrillation. J Am Coll Cardiol 2011; 58(17):1741-9.
  24. Gumbinger C, Krumsdorf U, Veltkamp R et al. Continuous monitoring versus HOLTER ECG for detection of atrial fibrillation in patients with stroke. Eur J Neurol 2012; 19(2):253-7.
  25. Lazzaro MA, Krishnan K, Prabhakaran S. Detection of atrial fibrillation with concurrent holter monitoring and continuous cardiac telemetry following ischemic stroke and transient ischemic attack. J Stroke Cerebrovasc Dis 2012; 21(2):89-93.
  26. Cotter PE, Martin PJ, Ring L et al. Incidence of atrial fibrillation detected by implantable loop recorders in unexplained stroke. Neurology 2013; 80(17):1546-50.
  27. Miller DJ, Khan MA, Schultz LR et al. Outpatient cardiac telemetry detects a high rate of atrial fibrillation in cryptogenic stroke. J Neurol Sci 2013; 324(1-2):57-61.
  28. Kamel H, Navi BB, Elijovich L et al. Pilot randomized trial of outpatient cardiac monitoring after cryptogenic stroke. Stroke 2013; 44(2):528-30.
  29. Ritter MA, Kochhauser S, Duning T et al. Occult atrial fibrillation in cryptogenic stroke: detection by 7-day electrocardiogram versus implantable cardiac monitors. Stroke 2013; 44(5):1449-52.
  30. Sinha AM, Diener HC, Morillo CA et al. Cryptogenic Stroke and underlying Atrial Fibrillation (CRYSTAL AF): design and rationale. Am Heart J 2010; 160(1):36-41 e1.
  31. Crawford MH, Bernstein SJ, Deedwania PC et al. ACC/AHA Guidelines for Ambulatory Electrocardiography. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Revise the Guidelines for Ambulatory Electrocardiography). Developed in collaboration with the North American Society for Pacing and Electrophysiology. J Am Coll Cardiol 1999; 34(3):912-48.
  32. Zimetbaum PJ, Josephson ME. The evolving role of ambulatory arrhythmia monitoring in general clinical practice. Ann Intern Med 1999; 130(10):848-56.
  33. Calkins H, Kuck KH, Cappato R et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. J Interv Card Electrophysiol 2012; 33(2):171-257.




CPT  33282  Implantation of patient-activated cardiac event recorder 
  33284  Removal of an implantable, patient-activated cardiac event recorder 
  93228 Wearable mobile cardiovascular telemetry with electrocardiographic recording, concurrent computerized real time data analysis and greater than 24 hours of accessible ECG data storage (retrievable with query) with ECG triggered and patient selected events transmitted to a remote attended surveillance center for up to 30 days; physician review and interpretation with report
  93229 ;technical support for connection and patient instructions for use, attended surveillance, analysis and physician prescribed transmission of daily and emergent data reports
  93268  Wearable patient activated electrocardiographic rhythm derived multiple event recording with presymptom memory loop, 24-hour attended monitoring, per 30 day period of time; includes transmission, physician review and interpretation 
  93270  Recording (includes connection, recording, and disconnection) 
  93271  Monitoring, receipt of transmissions, and analysis 
  93272  Physician review and interpretation only 
  0295T External electrocardiographic recording for more than 48 hours up to 21 days by continuous rhythm recording and storage; includes recording, scanning analysis with report, review and interpretation
   0296T ;recording (includes connection and initial recording)
   0297T ;scanning analysis with report
   0298T ;review and interpretation
ICD-9 Procedure  89.50  Ambulatory cardiac monitoring 
ICD-9 Diagnosis  426.9  Unspecified conduction disorder 
   427.31 Atrial fibrillation
  427.60  Premature beats, unspecified 
  427.89  Other specified cardiac dysrhythmias 
  427.9  Cardiac dysrhythmia, unspecified 
  780.2  Syncope and collapse 
  780.4  Dizziness 
  785.1  Palpitations 
ICD-10-CM (effective 10/1/15) I44.0- I44.7 Atrioventricular and left bundle-branch block code range  
   I45.0 – I45.9 Other conduction disorders code range  
   I47.0 – I47.9 Paroxysmal tachycardia code range  
  I48.0 – I48.1 Atrial fibrillation and flutter code range  
    I49.01 – I49.9 Other cardiac arrhythmias code range  
    R00.2 Palpitations  
  R42  Dizziness and giddiness  
    R55 Syncope and collapse 
ICD-10-PCS (effective 10/1/15)    ICD-10-PCS codes are only used for inpatient services.  
   4A12X45 Measurement and monitoring, physiological systems, monitoring, cardiac, external, electrical activity, ambulatory 
Type of Service Cardiology  
Place of Service Outpatient  


Ambulatory Event Monitoring
Arrhythmias, Monitoring
Cardiac Monitoring, Ambulatory Event
Insertable Loop Recorder
Mobile Outpatient Cardiac Telemetry
Reveal Device
Telemetry, Cardiac, Outpatient

Policy History

Date Action Reason
07/10/98 Add to Medicine Section New policy
11/01/99 Replace policy New CPT code; policy statement unchanged
07/12/02 Replace policy Policy updated; policy statement unchanged
04/29/03 Replace policy Policy reviewed without literature review; new review date only.
09/27/05 Replace policy Policy updated with review of auto-activated ambulatory event monitors, and outpatient cardiac telemetry. Policy statement revised to indicate that outpatient cardiac telemetry is not medically necessary. Reference numbers 4 through 8 added.
12/12/06 Replace policy Policy updated with literature review; policy statement unchanged. Reference number 9 added
04/17/07 Replace policy Policy updated with literature review; policy statement unchanged. Reference numbers 10 and 11 added 
09/18/07 Replace policy Policy updated, reference number 12 added
05/14/09 Replace policy Policy updated with literature search, references 13 and 14 added; clinical input reviewed, policy statement on MCOT changed from investigational to not medically necessary.
09/16/10 Replace policy Policy updated with literature search; reference numbers 8, 9, and 15 added. No change to policy statements
10/04/11 Replace policy

Policy updated with literature search; reference numbers 4,11,12 added. Medically necessary indication added to policy statement for use of autotrigger devices in treated patients with atrial fibrillation to evaluate for asymptomatic episodes.

11/10/11 Replace policy - coding update only New CPT category III codes 0295T-0298T added
11/08/12 Replace Policy Policy updated with literature search; reference numbers 17-24, 25 added. Medically necessary indication for use of event monitors in patients with atrial fibrillation treated with catheter ablation revised for clarity and for wording to be consistent with recent guidelines. Not medically necessary indication for MCOT changed to reflect revised language for not medically necessary technologies. Additional investigational indications added for use of continuous monitors that record for periods longer than 72 hours, and for monitoring patients with cryptogenic stroke.
11/08/12 Replace Policy Policy updated with literature search; reference numbers 17-24, 25 added. Medically necessary indication for use of event monitors in patients with atrial fibrillation treated with catheter ablation revised for clarity and for wording to be consistent with recent guidelines. Not medically necessary indication for MCOT changed to reflect revised language for not medically necessary technologies. Additional investigational indications added for use of continuous monitors that record for periods longer than 72 hours, and for monitoring patients with cryptogenic stroke.
03/14/13 Replace policy - correction only Corrected policy statement on continuous monitoring to say 48 hours rather than 72 hours – “Continuous ambulatory monitors that record and store information for periods longer than 48 hours are considered investigational.”
10/10/13 Replace policy Policy updated with literature review through August 2013, references 3, 10, 28, 29 added. Medically necessary criteria for implantable ambulatory event monitors revised from “…a prior trial of Holter monitor and other external ambulatory event monitors has been unsuccessful” to “…a prior trial of other external ambulatory event monitors has been unsuccessful.” The policy statement on outpatient cardiac telemetry was reworded and language was added that the least costly alternative may be considered medically necessary.
11/14/13 Replace policy-correction only Policy History for October 2013 revised to change “loop monitors” to “ambulatory event monitors” and add “The policy statement on outpatient cardiac telemetry was reworded and language was added that the least costly alternative may be considered medically necessary.”