Mobile Cardiac Telemetry and Implantable Loop Recorders
This policy governs medical necessity review and coverage criteria for ILR implantation and MCOT use for outpatient cardiac rhythm monitoring, affecting providers who order or perform these monitoring services for patients with suspected arrhythmia or cryptogenic stroke.
Title changed to Mobile Cardiac Telemetry and Implantable Loop Recorders and implantable loop recorders were added as medically necessary when criteria are met.
CPT code 33285 and HCPCS codes C1764 and E0616 were added.
Policy criterion added requiring prior non-diagnostic or inconclusive ambulatory cardiac monitoring of at least 14 continuous days for ILR placement.
Expanded not medically necessary policy statement to include ILRs and monitoring of asymptomatic individuals.
Removed the term 'ambulatory event monitor (AEM)' for clarity and made minor edits clarifying site of service review applies only to ILR.
Added SOS ASC and Site of Service Ambulatory Service Center (ASC) related policy for ILR procedures.
Coverage Criteria for ILR and MCOT
inv-01: ILR (Implantable Loop Recorder) - Initial — Covered when ALL of the following are met
Covered when ALL of the following are met:
ILR may be auto-activated or patient-activated
inv-02: MCOT (Mobile Cardiac Outpatient Telemetry) - Initial — Covered when ALL of the following are met
Covered when ALL of the following are met:
Examples of MCOT: CardioNet, LifeStar, ZioAT
inv-03: MCOT — Appropriate use in selected patients — Covered when ALL of the following are met
Covered when ALL of the following are met:
Derived from clinical input supporting MCOT in a subgroup of appropriately selected individuals.
inv-04: Implantable loop recorder — escalation from external monitoring — Covered when ALL of the following are met
Covered when ALL of the following are met:
Based on RCTs and observational studies showing higher detection with ILR.
inv-05: Use of mobile cardiac outpatient telemetry (MCOT) — clinical input-supported scenarios — Covered when ALL of the following are met for individuals with infrequent symptoms or specific indications:
Covered when ALL of the following are met for individuals with infrequent symptoms or specific indications:
From 2025 clinical input supporting MCOT in a subgroup of appropriately selected individuals
inv-06: MCOT or extended monitoring for cryptogenic stroke — Covered when ALL of the following are met for evaluation of cryptogenic stroke:
Covered when ALL of the following are met for evaluation of cryptogenic stroke:
Supported by guideline statements (AHA/ACC/HRS and ISHNE/HRS).
inv-07: Implantable Loop Recorder - Added criteria — ILRs considered medically necessary when ALL new listed conditions are met (policy added ILR coverage and prerequisites):
ILRs considered medically necessary when ALL new listed conditions are met (policy added ILR coverage and prerequisites):
Additional ILR medical necessity criteria in prior sections must also be met.
inv-08: MCOT - policy status — MCOT / mobile cardiac telemetry
MCOT / mobile cardiac telemetry:
Full historical policy language and code additions are recorded in the policy history.
Other uses of mobile cardiac outpatient telemetry (MCOT) and implantable loop recorders (ILRs) are considered not medically necessary when the coverage criteria above are not met. Examples of such noncovered uses include monitoring of asymptomatic individuals for risk factors for arrhythmia, routine surveillance of the effectiveness of antiarrhythmic medications, or attempting detection of myocardial ischemia by ST‑segment changes. Documentation supporting medical necessity per the policy must be provided for any requested monitoring service (including relevant prior monitoring and clinical history).
The policy does not support use of MCOT solely to increase arrhythmia detection when real‑time monitoring will not change management or improve outcomes. MCOT’s theoretical advantage is real‑time event transmission and potential emergent intervention, but randomized evidence that real‑time monitoring alone changes clinical management or reduces mortality is lacking; therefore MCOT is appropriate only when real‑time detection would be expected to prompt immediate clinical actions.
Prior clinical input did not reach consensus that MCOT universally provides incremental benefit over external event monitors. Reviewers agreed MCOT is comparable for arrhythmia detection but differed on whether the real‑time feature adds outcome benefit. The policy therefore limits MCOT use to scenarios where real‑time monitoring is likely to be essential and where other external monitors of adequate duration would be insufficient.
The policy explicitly expands the not medically necessary scope to include monitoring of asymptomatic individuals, including use of ILRs for asymptomatic surveillance. Requests for monitoring asymptomatic members should be evaluated as noncovered under this policy.
Use of MCOT or ILRs for indications that do not meet the stated medical necessity criteria is considered not medically necessary. This includes, but is not limited to, asymptomatic risk‑factor monitoring, routine assessment of antiarrhythmic drug effectiveness, or attempts to detect ischemia by ST‑segment changes. When other external monitors with sufficient recording duration (e.g., patch monitors ≥14 days) are appropriate, MCOT is not routinely supported.
Routine use of MCOT solely to detect arrhythmias without a documented plan for immediate clinical action is not supported. Because available studies have not demonstrated that real‑time detection by MCOT leads to improved clinical outcomes, MCOT should be reserved for cases where documentation shows that prompt detection would change management (for example, emergency intervention or immediate medication adjustment).
When real‑time monitoring does not provide an incremental benefit over external event monitors, or when other external monitors provide adequate recording duration, MCOT is not considered medically necessary. The policy reflects prior input noting uncertainty about outcome advantages of MCOT and supports selecting the monitoring modality based on symptom frequency and the likelihood that real‑time transmission will affect care.
Use of ILRs and other ambulatory monitoring for asymptomatic individuals is considered not medically necessary under the expanded policy statement. Requests for ILR insertion (e.g., CPT 33285) or related HCPCS codes added to the policy should include documentation that the member meets the ILR medical necessity criteria; absent such documentation, coverage may be denied.
Covered CPT code included in the policy: 33285 (Insertion, subcutaneous cardiac rhythm monitor, including programming). This CPT code was added to the policy during the recent updates and requires prior authorization with documentation that medical necessity criteria are met.
Billing and Coding
| 33285 | Insertion, subcutaneous cardiac rhythm monitor, including program. |
| 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; review and interpretation with report by a physician or other qualified health care professional. |
| DSH | FDA product code (ambulatory cardiac monitor category) |
| DXH | FDA product code (ambulatory cardiac monitor category) |
| DQK | FDA product code (ambulatory cardiac monitor category) |
| DSI | FDA product code (ambulatory cardiac monitor category) |
| MXD | FDA product code (ambulatory cardiac monitor category) |
| MHX | FDA product code (ambulatory cardiac monitor category) |
| 33285 | Insertion of insertable cardiac monitor (ICM) — code added to policy |
Provider Requirements and Operational Steps
Prior Authorization Required
Prior authorization is required when seeking coverage for ILR implantation (CPT 33285) or MCOT services (CPT 93228, 93229). Requests must include documentation that real-time monitoring is essential for patient safety and will lead to immediate clinical actions (e.g., medication changes, urgent procedures).
MCOT Supported When Real-Time Monitoring Essential
MCOT is supported for a subgroup of appropriately selected individuals with infrequent but clinically significant symptoms when prior external monitoring was non-diagnostic or contraindicated and real-time monitoring is essential for safety and immediate management.
- MCOT may be considered medically necessary when: prior external ambulatory cardiac event monitoring of at least 14 continuous days was non-diagnostic or contraindicated; symptoms occur less frequently than every 48 hours (infrequent) but are clinically significant; and real-time monitoring is required to ensure patient safety and enable immediate clinical interventions.
- Clinical input supports MCOT for recurrent unexplained presyncope, syncope, severe palpitations, or dizziness when symptoms are likely due to arrhythmia.
Medical Necessity Documentation for Coverage
Medical necessity must be documented in the medical record. Documentation should clearly show that all applicable clinical criteria are met and include specific prior monitoring details, symptom descriptions, and rationale for chosen device.
- Office visit notes with pertinent history and physical exam.
- Symptom diary or event log describing frequency, severity, and circumstances of episodes.
- Results and interpretation of prior external monitoring (including duration and whether non-diagnostic).
- For cryptogenic stroke evaluation: documentation of negative standard AF workup including 24-hour Holter, when applicable.
Documentation of Necessity for Real-Time Monitoring
When claiming that real-time monitoring is necessary, provide clinical justification that real-time data will materially change immediate management and is required for patient safety (for example, suspected life‑threatening arrhythmias where prompt intervention is possible).
- Explain why Holter/external AEM is insufficient or contraindicated.
- Describe how emergent detection would change management (e.g., urgent hospitalization, electrophysiology intervention, immediate medication adjustment).
- State anticipated monitoring duration and expected yield.
Required Documentation for Medical Necessity
Required documentation elements for medical necessity include evidence of prior non-diagnostic or inconclusive ambulatory cardiac monitoring of at least 14 continuous days, clinical description of symptoms, and supporting diagnostic test results.
- Evidence of prior external ambulatory cardiac monitoring ≥14 continuous days with non-diagnostic result.
- Description of recurrent unexplained presyncope, syncope, palpitations, or dizziness.
- For suspected AF in cryptogenic stroke: negative standard workup including 24-hour Holter.
- Relevant office notes, ECGs, and prior monitor reports.
Device Selection by Symptom Frequency
Select the monitoring device based on symptom frequency and nature. Short‑duration frequent symptoms favor Holter or short external monitors; infrequent but clinically significant events may require external event monitors, MCOT, or progression to an ILR when warranted.
- Holter monitor: preferred when events occur within 48 hours or very frequently.
- External ambulatory event monitors/patch recorders: for intermittent symptoms occurring more often than monthly but less frequent than daily.
- MCOT: for infrequent but potentially emergent symptoms when real-time monitoring is justified and prior external monitoring was nondiagnostic or contraindicated.
- ILR: when prolonged monitoring is needed or prior external monitoring (≥14 days) was non-diagnostic.
Required Prior External Monitoring
Before proceeding to ILR implantation or MCOT, at least 14 continuous days of external ambulatory cardiac monitoring must have been performed and documented as non‑diagnostic, unless external monitoring is contraindicated.
- Prior external ambulatory cardiac monitoring ≥14 continuous days is required and must be documented as non-diagnostic.
- If external monitoring is contraindicated, provide clinical rationale in the record.
Step from External Monitors to ILR
Progression from external monitors to ILR is supported when longer-term monitoring is needed to capture infrequent events and prior external monitoring (≥14 days) was non-diagnostic.
- Use ILR when symptoms are infrequent and prior external monitoring did not yield a diagnosis.
- Document that extended monitoring duration of ILR is clinically necessary to detect suspected arrhythmia.
Prior Non-Diagnostic Monitoring Requirement
A prior non-diagnostic monitoring requirement is enforced: requests for ILR implantation or MCOT lacking documentation of at least 14 continuous days of prior non-diagnostic external ambulatory cardiac monitoring will be at high risk for denial unless a valid contraindication is documented.
- Denial risk if prior external monitoring ≥14 days is not documented or the monitoring was diagnostic.
- If claiming contraindication to external monitoring, include clear clinical justification.
Definitions and Device Types
Background and Evidence Summary
Implantable loop recorders (ILRs) and mobile cardiac outpatient telemetry (MCOT) provide extended outpatient cardiac rhythm monitoring to detect intermittent arrhythmias such as atrial fibrillation, bradycardia, or tachyarrhythmias that may be missed on brief in‑office testing. MCOT delivers continuous external telemetry with real‑time transmission and central analysis typically for up to ~30 days, enabling immediate notification of detected events; ILRs are subcutaneous devices that provide long‑term automatic surveillance over months to years and are useful when symptoms are infrequent.
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