Insertable cardiac monitors (ICMs) — also known as implantable loop recorders (ILRs) — have become essential tools for long-term cardiac rhythm monitoring. They help diagnose unexplained syncope, detect atrial fibrillation, monitor cryptogenic stroke patients, and evaluate intermittent arrhythmias that cannot be captured on short-term monitors.
The CPT code used for insertion or replacement of an insertable cardiac monitor is 33285. This minimally invasive procedure is typically performed in the office, ambulatory surgery center, cath lab, or EP lab. Because ILR implantation is a high-value service with strict payer rules, accurate coding and documentation are crucial.
This comprehensive guide explains exactly how to bill CPT 33285, what it includes, what it doesn’t, medical necessity, device types, payer requirements, ICD-10 pairing, documentation rules, prior authorization, and how to avoid the most common denials.
Strengthen your revenue cycle with the most detailed Cardiology Billing and Coding Guide covering E&M, procedures, imaging, stress testing, NCCI edits, and more.
What Is CPT 33285?
Official CPT description:
“Insertion, subcutaneous cardiac rhythm monitor, including programming.”
In simple, clinical terms:
CPT 33285 = Insertion OR replacement of a subcutaneous insertable cardiac monitor (ICM/ILR) + initial device programming.
This code applies to ILR/ICM devices such as:
- Medtronic Reveal LINQ / LINQ II
- Abbott Confirm Rx
- Biotronik Biomonitor
- Boston Scientific LUX-Dx ICM
The code covers both:
- New implants
- Removal-and-replacement procedures (as long as a new ICM is inserted)
If removal ONLY is performed, different codes apply (explained below).
What CPT 33285 Includes
Billing CPT 33285 includes the full ILR implantation workflow:
1. Subcutaneous Incision and Pocket Creation
A small incision (typically 1 cm) is made below the pectoral region or left parasternal area. Improve accuracy and avoid payer denials with our comprehensive CPT 92960 Electrical Cardioversion Billing Guide covering documentation, clinical scenarios, and modifier rules.
2. ILR/ICM Device Insertion
The tunneling tool is used to place the device in the subcutaneous pocket.
3. Hemostasis, Closure, and Dressing
- Steri-strips, Dermabond, or sutures
- Clean wound closure
4. Initial Device Programming
Only the initial programming is included.
Includes:
- Setting detection parameters (e.g., AF, brady, tachy detection)
- Configuring symptom activation sensitivity
- Enabling diagnostic reporting
5. Final Testing
Ensuring:
- Adequate sensing
- Appropriate R-wave amplitude
- Device stability
6. Post-Procedure Monitoring and Instructions
Included as part of the implantation service.
What CPT 33285 Does NOT Include
Certain services must be billed separately when appropriate.
1. Device Removal
If removing an old ILR WITHOUT inserting a new one:
- Use CPT 33286 (removal only)
If removal + insertion occur the same day:
- Bill ONLY 33285 (covers replacement)
2. Remote Monitoring
Use separate remote monitoring codes (typically 93298 for professional component, 93297 for technical).
3. ECG/EKG
If medically necessary and separately documented:
- 93000 (ECG with interpretation)
4. Imaging Guidance
Ultrasound guidance for ILR implantation:
- NOT separately billable (considered bundled)
5. Sedation
If moderate sedation is provided:
- May bill 99152–99153 when criteria are met.
When to Use CPT 33285
CPT 33285 is used when a provider inserts an insertable cardiac monitor to evaluate episodic or unexplained symptoms.
Reduce approval delays by reviewing our essential Cardiology Prior Authorization Guide with payer requirements, documentation templates, and workflow best practices.
Most Common Indications:
1. Unexplained Syncope
When:
- Holter or event monitors are nondiagnostic
- Syncope occurs infrequently
- Structural causes have been ruled out
2. Cryptogenic Stroke Workup
To detect occult atrial fibrillation.
3. Suspected Intermittent Arrhythmias
Particularly when symptoms are rare, such as:
- Palpitations
- Near-syncope
- Atypical chest discomfort with arrhythmic suspicion
4. Evaluation for Atrial Fibrillation Recurrence
Post-ablation or after cardioversion.
5. Bradyarrhythmias or Tachyarrhythmias
Suspected but not captured by short-term monitoring.
6. Seizure-like Episodes
When arrhythmia-induced cerebral hypoperfusion is suspected.
7. Monitoring Ventricular Arrhythmia Risk
Selected high-risk patients.
When NOT to Use CPT 33285
Do not bill 33285 if:
❌ Only the ILR was removed
Use 33286.
❌ Only device reprogramming was performed
Use 93291 for device interrogation/programming.
❌ The procedure was a diagnostic Holter/event monitor hookup
That uses entirely different codes (e.g., 93224, 93228, 93268).
❌ A wearable or external monitor was used
ILR-only code applies to insertable devices.
❌ The procedure was aborted before device insertion
Use modifier -53 or appropriate reduced-service codes.
Documentation Requirements
To avoid denials, documentation must include the following:
1. Medical Necessity Documentation
- Symptoms: syncope, palpitations, cryptogenic stroke, dizziness
- Failed prior monitoring attempts
- Reason: long-term monitoring is required
2. Pre-Procedure Evaluation
- Rhythm assessment
- Anticoagulation review
- Informed consent
3. Procedure Details
Must include:
- Incision site
- Device type and manufacturer
- Programming parameters
- R-wave sensing values
- Hemostasis method
- Incision closure details
4. Device Activation & Transmission Setup
Document:
- Home monitor/smartphone app pairing
- Remote monitoring enrollment
5. Post-Procedure Instructions
- Wound care
- Activity restrictions
- Transmission expectations
6. Physician Signature
Missing ANY of these leads to denials or audits.
ICD-10 Codes Commonly Billed With 33285
Here are the most commonly accepted ICD-10 codes:
Syncope & Related Symptoms
- R55 – Syncope
- R42 – Dizziness
Atrial Fibrillation & Flutter
- I48.0 – Paroxysmal AF
- I48.1 – Persistent AF
- I48.21 – Permanent AF
- I48.3 – Typical flutter
Cryptogenic Stroke
- I63.9 – Cerebral infarction, unspecified
- Z86.73 – Personal history of TIA/stroke
Palpitations & Arrhythmias
- R00.2 – Palpitations
- I49.9 – Cardiac arrhythmia, unspecified
- I47.1 – SVT
- I47.2 – VT
Cardio-neurologic Symptoms
- G40.909 – Seizure disorder
- R40.4 – Transient loss of consciousness
Using ICD-10 codes outside these groups may trigger medical necessity denials.
Prior Authorization for CPT 33285
Prior authorization is almost ALWAYS required except in Medicare.
Medicare
- NO prior authorization required
- But documentation must show medical necessity
Medicare Advantage
- PA is almost always required
Commercial Payors (Aetna, Cigna, UHC, BCBS)
Most require PA for:
- Cryptogenic stroke evaluation
- Syncope
- Afib monitoring
Medicaid
PA required in most states.
Reimbursement for CPT 33285
Typical national reimbursement ranges:
Facility Setting
- $6,000–$10,000 (device + implantation combined)
Physician Professional Fee
- $350–$500
Rates vary widely by payer contract and location.
Because ILRs are high-cost devices, payers scrutinize these claims closely.
Modifier Considerations
Modifier -RT / -LT
NOT used — ILR placement is midline and not considered laterality-specific.
Modifier -52 (Reduced Services)
Use for:
- Aborted procedures
- Partial pocket creation without device insertion
Modifier -53 (Discontinued Procedure)
Use when the procedure is discontinued due to patient instability.
Modifier -76 / -77
Rare for ILRs, but may apply for repeat insertion on the same day.
Modifier -22 (Increased Procedural Services)
Possible if:
- Reoperation through scar tissue
- Significant hematoma evacuation
- Extensive dissection required
Documentation must justify increased work.
Common Denials for CPT 33285
❌ 1. Medical necessity not supported
Fix: Document syncope, failed monitors, cryptogenic stroke, etc.
❌ 2. PA not obtained
Fix: Always verify authorization BEFORE implant.
❌ 3. Wrong diagnosis
Fix: Use accepted arrhythmia/syncope/stroke ICD-10 codes.
❌ 4. Missing programming documentation
Fix: Include programming parameters + device pairing.
❌ 5. Billed with the wrong removal code
Remember: replacement = 33285 (not 33286).
❌ 6. Provider billed remote monitoring incorrectly
Use 93297/93298 appropriately.
Final Thoughts
CPT 33285 represents one of the key procedures in cardiac rhythm management, especially in evaluating unexplained arrhythmias and cryptogenic stroke. Because ILR implantation involves a high-cost device and strict payer rules, correct coding and strong documentation are essential.
If your cardiology practice needs help improving ILR billing accuracy, optimizing PA workflows, or reducing denials, Global Tech Billing LLC provides specialized cardiology RCM services designed to maximize reimbursement and ensure compliance.
Frequently Asked Questions (FAQ)
1. Does CPT 33285 include the device cost?
Yes — in a facility billing scenario, the device cost is included.
2. Is programming included?
Only initial programming is included.
Reprogramming uses 93291.
3. Can 33285 be billed in an office?
Yes — if the office is properly accredited and device reimbursement policies allow it.
Improve accuracy in device, ablation, and EP study billing using our expert Electrophysiology Billing & Coding Guide designed to help EP practices reduce audits and claim rejections.
4. Can remote monitoring be billed the same month as the implant?
Yes — with
- 93298 (professional)
- 93297 (technical)
5. Can TEE or echo be billed on the same day?
Yes — if medically necessary and unrelated to implantation.
