This document addresses the use of external (nonimplanted) ambulatory event monitors (AEMs) that are not equipped for real-time physician notification. Examples of devices addressed in this document include  continuous 24- to 48-hour Holter monitors.

This document does not address implantable ambulatory event monitors or the use of AEMs equipped with cellular telecommunications equipment for real time physician notification. For information related to these devices, refer to:

• CG-MED-74 Implantable Ambulatory Event Monitors and Mobile Cardiac Telemetry

Also, this document does not address attended, real-time electrocardiogram monitoring.

Clinical Indications

I.  Ambulatory Electrocardiograph (ECG) Holter Monitor

Medically Necessary:

Continuous 24- to 48-hour ambulatory ECG Holter monitor use is considered medically necessary for adults with any of the following indications:

1. As a diagnostic tool to evaluate frequent, unexplained symptoms suggestive of cardiac arrhythmias such as palpitations, unexplained dizziness or syncope or near syncope; or
2. Evaluation of hypertrophic cardiomyopathy or dilated cardiomyopathies; or
3. As a diagnostic tool for detecting ventricular arrhythmias, QT interval changes, or ST changes, to evaluate risk; or
4. As a method to assess treatment response to antiarrhythmic therapy (efficacy; proarrhythmic effect); or
5. As a method to assess for paroxysmal atrial fibrillation following cryptogenic stroke; or
6. As a method to assess for asymptomatic atrial fibrillation three or more months after ablation of arrhythmogenic foci for atrial fibrillation; or
7. Assessment of the function of pacemakers or implantable cardioverter defibrillators (ICD) in individuals:
   1. with frequent symptoms of palpitation, syncope, or near syncope to assess device function to exclude myopotential inhibition and pacemaker mediated tachycardia; or
   2. to assist in programming parameters such as rate-responsivity and automatic mode switching; or
   3. to evaluate suspected component failure or malfunction when device interrogation is not definitive; or
   4. to assess response to adjunctive pharmacologic therapy in individuals receiving frequent ICD therapy; or
8. Suspected variant angina.

Continuous 24- to 48-hour ambulatory ECG Holter monitor use is considered medically necessary for children with any of the following indications:

1. As a diagnostic tool to evaluate frequent, unexplained symptoms suggestive of cardiac arrhythmias such as palpitations, unexplained dizziness or syncope or near syncope; or
2. Evaluation of hypertrophic cardiomyopathy or dilated cardiomyopathies; or
3. Evaluation of possible or documented long QT syndromes; or
4. As a method to assess treatment response to antiarrhythmic therapy (efficacy; proarrhythmic effect); or
5. Palpitations in children with prior surgery for congenital heart disease and significant residual hemodynamic abnormalities; or
6. Asymptomatic, unpaced, congenital complete atrioventricular (AV) block; or
7. Evaluation of cardiac rhythm after transient (AV) block associated with heart surgery or catheter ablation; or
8. Evaluation of rate-responsive or physiological pacing function in children with persistent or recurrent cardiac symptoms.

Not Medically Necessary:

Ambulatory ECG Holter monitor use is considered not medically necessary when the above criteria are not met.

Ambulatory ECG Holter monitor use is considered not medically necessary for all other indications including, but not limited to:

• Autonomic cardiac neuropathy associated with diabetes mellitus
• After a myocardial infarction when the individual has left ventricular dysfunction (ejection fraction [EF] less than or equal to 40%)

II.  External Ambulatory Event Monitor

Medically Necessary:

The use of external ambulatory event monitors is considered medically necessary when EITHER of the following criteria are met (A or B):

1. As a diagnostic alternative to Holter monitoring, in individuals who experience infrequent symptoms (less frequently than once every 48 hours) suggestive of cardiac arrhythmias; or
2. Following cryptogenic stroke, for the detection of suspected paroxysmal atrial fibrillation when prior testing with Holter monitoring has yielded inconclusive results and when external ambulatory event monitoring is intended to guide medical management with anticoagulants.

Not Medically Necessary:

Other uses of external ambulatory event monitors and telemetry are considered not medically necessary including, but not limited to, the following clinical situations:

• Monitoring effectiveness of antiarrhythmic therapy and detection of myocardial ischemia by detecting ST segment changes
• Following catheter or surgical ablation of atrial fibrillation
• Monitoring for the presence of atrial fibrillation in individuals with cryptogenic stroke when the criteria are not met