Ambulatory ECG monitoring is one of the most commonly ordered diagnostic services in cardiology. It is also among the most frequently denied or audited due to incorrect code selection, mismatched documentation, and confusion between Holter, event monitors, patch monitors, external loop recorders, and extended continuous ECG systems.
This guide breaks down each code family in the 93224–93248 range, explains documentation rules, helps differentiate multiple monitoring modalities, and highlights the audit traps that practices should avoid.
Understanding Ambulatory ECG Monitoring Modalities
Ambulatory ECG monitoring is broadly divided into:
- Holter monitoring (24–48 hours)
- Extended continuous ECG monitoring (greater than 48 hours to 15 days)
- Event recording (patient-activated or automatically triggered)
- External loop recording (ELR)
- Patch-based monitors (Zio, Bardy, etc.)
- Mobile cardiac telemetry (MCT) — note: usually billed with 93228–93229 (not part of this guide but often confused)
Each modality has distinct CPT codes, coverage criteria, and documentation expectations.
Using the wrong code is a guaranteed denial.
Holter Monitoring Codes: 93224–93227
Holter monitors are continuous, uninterrupted ECG recordings for 24–48 hours.
The code set includes global, professional-only, and technical-only options.
93224 – Global (Monitoring + Scanning/Analysis + Report)
Includes:
- Device hook-up
- 24–48 hour continuous recording
- Analysis/scanning
- Final physician interpretation and report
- Bill this only when your practice provides all components.
93225 – Recording (Technical Component)
Used when your office provides the device and recording only.
No scanning or provider interpretation is included.
93226 – Scanning/Analysis (Technical Component)
Used when a third party provides scanning or when scanning is performed internally, but the interpreting doctor bills separately.
93227 – Physician Interpretation and Report (Professional Component)
Used when the physician provides only interpretation and final report.
Key points for Holter:
- Duration must be 24–48 hours; if less than 24 hours or more than 48, these codes are not appropriate.
- The service must be continuous recording—not intermittent or triggered.
- If the patient fails to wear the device for a full interpretable period, documentation must reflect the duration, and the code selection must be appropriate.
Holter is one of the easiest services to code correctly, but the most common mistakes arise when practices confuse these with extended monitoring codes (93241–93248).
Extended Ambulatory ECG Monitoring (Greater Than 48 Hours): 93241–93248
These codes apply to continuous ECG monitoring for more than 48 hours, up to 15 days.
This category includes patch-based monitors commonly used in cardiology.
There are several important distinctions:
- These codes are NOT Holter codes.
- They do not include loop/event recording.
- They represent long-term continuous monitoring, not intermittent triggered episodes.
Global Codes
93241 – 48 hours to 7 days (global)
Includes:
- Device setup
- Recording
- Scanning/analysis
- Physician interpretation
- Report
93243 – Greater than 7 days, up to 15 days (global)
Same components as 93241, but for a longer duration.
Technical-Only Codes
93242 – Recording only (48 hours to 7 days)
93244 – Recording only (>7 days to 15 days)
These are used when your practice supplies the device and recording, but does not perform interpretation.
Interpretation-Only Codes
93245 – Scanning/analysis + physician report (48 hours to 7 days)
93247 – Scanning/analysis + physician report (>7 days to 15 days)
Scanning-Only Codes
93246 – Scanning/analysis only (48 hours to 7 days)
93248 – Scanning/analysis only (>7 days to 15 days)
Critical guidance:
- These codes do not apply to durations >15 days; different codes or MCT may be required.
- Do not use Holter codes for patch monitors that exceed 48 hours.
- Physicians performing interpretation only must NOT bill global codes.
Event Monitoring & External Loop Recording Are NOT the Same as Extended ECG
A common audit failure is misusing extended ECG codes for event monitors or external loop recorders.
Extended ECG (93241–93248):
- Continuous recording for 48 hours to 15 days
- No looping mechanism
- No patient-triggered activation
- Scan is performed at the end of the monitoring period
Event Monitoring (e.g., 93268, 93270–93272):
- Intermittent, triggered recording
- Real-time or near-real-time transmissions
- NOT covered in this code guide, but highly confused
Using extended ECG codes for an event/loop recorder is an automatic denial.
Documentation Requirements for Holter and Extended ECG Monitoring
Payers require specific documentation to support:
- Medical necessity
- Correct code selection
- Duration of monitoring
- Interpretation of results
Required Elements
- Clinical indication
- Examples:
- Palpitations
- Dizziness
- Syncope
- AFib burden monitoring
- Premature ventricular contraction (PVC) assessment
- Cryptogenic stroke evaluation
- Order specifying the requested monitoring duration
- Must match the billed CPT code.
- Device hook-up documentation
- Date/time device placed
- Instructions given
- Condition of the patient
- Electrode/pad placement verified
- Monitoring duration
- Payers compare documentation with the claim:
- Holter must be 24–48 hours
- An extended ECG must exceed 48 hours
- For >7 days, billing must match one of the 93243/93244/93247/93248 codes
- Scanning/analysis details
- Arrhythmia events identified
- Summary of findings
- Total analyzable time
- Number of artifacts
- Physician interpretation & final report
- Must include:
- Summary of rhythms
- Presence/absence of arrhythmias
- Burden of AFib/PVCs
- Clinical correlation
- Physician signature/date
If any step is missing or unclear, commercial payers often deny the claim.
Common Audit Triggers in Holter & Extended ECG Billing
These services are highly audited. The most common triggers include:
1. Mismatched duration and code selection
Examples:
- 24-hour monitoring billed as 93241
- 10-day patch study billed using Holter code 93224
- 7-day monitor incorrectly billed as >7-day code
2. Missing medical necessity documentation
Auditors deny when the chart states only:
- “Palpitations”
- “Check arrhythmia”
- “Patient follow-up”
Diagnosis must be tied to symptoms or conditions.
3. Billing global codes when components are split
If the physician only interprets the ECG, they must use 93227 or 93245/93247, depending on duration.
4. Duplicate billing when the vendor also bills
Some third-party vendors automatically bill their portion.
Practices need to ensure roles are clear.
5. Unclear interpretation
Interpretation must not be:
- “Normal”
- “Monitor reviewed”
- “Sinus rhythm”
A full interpretation is required.
6. Overlapping monitoring periods
Payers deny if:
- Multiple devices are used for overlapping dates
- Holter + extended code are billed for the same timeframe
- Event and patch monitors overlap
7. Missing scanning documentation
Scanned data must be documented even if interpreted externally.
Coding Examples
Example 1: 48-Hour Holter in Clinic
Practice provides device, scanning, and interpretation → 93224
Example 2: Hospital provides device and recording, cardiologist interprets →
- Hospital: 93225 + 93226 (technical)
- Cardiologist: 93227 (professional interpretation)
Example 3: 10-Day Patch Monitor, Full Service in Clinic
Use 93243 (global >7 to 15 days)
Example 4: Cardiologist interprets 14-Day Monitor (scanning done by vendor)
Vendor: bills technical scanning (93248)
Cardiologist: bills 93247
Example 5: 5-Day Patch, Vendor Provides Device but Clinic Interprets
Vendor: 93242 (technical recording)
Clinic: 93245 (interpretation)
Example 6: Patient returns device early (3-day monitoring)
Extended ECG codes may still apply if:
- Monitoring exceeded 48 hours
- Data is interpretable
- Document actual duration.
Key Distinctions Between Holter, Patch, Loop Recorder, and MCT
Holter (93224–93227)
- Always continuous
- Always 24–48 hours
- Typically, 3-lead or 5-lead
Extended Patch (93241–93248)
- Continuous
- 48 hours to 15 days
- Single-use adhesive patch monitors
Event/Loop Recorder (NOT covered in this code set)
- Intermittent
- Patient-activated or auto-triggered
- Up to 30 days
Mobile Cardiac Telemetry (93228–93229)
- Continuous + real-time transmission
- Requires live algorithm analysis
- Much higher coding requirements
Understanding these categories prevents miscoding.
Best Practices to Avoid Denials
Always match documentation to the CPT code duration.
Start/stop times must be clear.
Maintain a monitoring log.
Many practices use:
- Device ID
- Serial number
- Patient return date
- Duration
- Technical staff initials
Ensure that interpreting physicians sign promptly.
Unsigned or late-signed reports often trigger recoupments.
Clarify agreements with vendors.
Prevent double-billing.
Avoid using modifier 25 or 59 unless necessary.
These services rarely need modifiers.
Build standardized templates
Include:
- Clinical indication
- Recording length
- Summary findings
- Recommendations
- Signatures
Templates reduce variability and audit exposure.
Conclusion
Holter and extended ECG monitoring are invaluable diagnostic tools in modern cardiology, but their coding rules can be confusing due to duration-based CPT selection, component-based billing, and overlapping monitoring technologies.
Accurate documentation, proper duration tracking, and correct application of CPT codes 93224–93248 are essential for compliant billing and to avoid denials or audits. Practices often prevent errors by using structured workflows, monitoring logs, and standardized reporting templates. When needed, teams also collaborate with specialized billing resources, such as Global Tech Billing LLC, to maintain accurate and compliant cardiology coding practices.
FAQs
1. What duration qualifies for a Holter monitor?
Holter monitors are continuous 24–48 hour ECG recordings.
2. When should extended ECG codes (93241–93248) be used?
For continuous monitoring longer than 48 hours, up to 15 days.
3. Can a patch monitor be billed with Holter codes?
No. Patch monitors exceeding 48 hours require extended ECG codes.
4. What are the components included in global codes?
Device setup, recording, scanning/analysis, and physician interpretation.
5. Can multiple monitors be billed concurrently?
No. Overlapping monitoring periods trigger denials.
6. What documentation is required for interpretation-only billing?
A full report including rhythm summary, arrhythmia burden, and clinical correlation.
7. Are event monitors billed with these codes?
No. Event/loop monitors use different CPT codes.
8. Can the Holter code 93224 be billed if the patient only wore it 12 hours?
No. Holter must be 24–48 hours; another code may apply depending on circumstances.
