Cardiology is one of the highest-revenue medical specialties — and one of the highest-risk from a billing perspective. With procedures that can reimburse thousands of dollars per claim, cardiology billing errors are expensive. A missing modifier, a bundling violation, or an incorrect place of service code can result in a denial worth $800–$5,000 per claim. Multiply that across a busy cardiology practice and the financial impact is significant.

This guide covers the most commonly billed cardiology CPT codes, the modifier rules that trip up most practices, and the specific compliance risks that make cardiology a frequent OIG audit target.

Echocardiography CPT Codes

Echocardiography is the highest-volume diagnostic procedure in most cardiology practices. Selecting the correct echo code depends on the type of study performed, whether it is a complete or limited study, and — critically — whether the physician owns the equipment or is only performing the professional interpretation.

Transthoracic Echocardiography (TTE)

• 93306 — Echocardiography, transthoracic, real-time, with image documentation, complete — includes 2D, M-mode, spectral Doppler, and color flow Doppler. Most commonly billed echo code in cardiology practice.
• 93307 — TTE, real-time with image documentation, without spectral or color Doppler (2D only)
• 93308 — TTE, real-time with image documentation, follow-up or limited study — use when only select views are obtained, not a complete study

Transesophageal Echocardiography (TEE)

• 93312 — Echocardiography, transesophageal, real-time with image documentation, includes probe placement, image acquisition, interpretation and report
• 93313 — TEE placement of probe only (without interpretation)
• 93314 — TEE image acquisition, interpretation and report only (without probe placement)
• 93315 — TEE, for congenital cardiac anomalies — used in structural heart disease and congenital cases
• 93316 — TEE for congenital cardiac anomalies — probe placement only
• 93317 — TEE for congenital cardiac anomalies — image acquisition and interpretation only

Stress Echocardiography

• 93350 — Echocardiography during rest and cardiovascular stress test — pharmacological stress only
• 93351 — Echocardiography during rest and cardiovascular stress test — includes use of pharmacological stress agent and interpretation

Electrocardiography (ECG/EKG) CPT Codes

• 93000 — Electrocardiogram, routine ECG with at least 12 leads — with interpretation and report (global — physician owns equipment and interprets)
• 93005 — ECG — tracing only, without interpretation and report (technical component only)
• 93010 — ECG — interpretation and report only (professional component only — use with Modifier 26)

Cardiac Monitoring CPT Codes

• 93224 — External electrocardiographic recording up to 48 hours (Holter monitor) — includes recording, scanning analysis with report, physician review and interpretation
• 93225 — Holter recording only (without analysis or interpretation)
• 93226 — Holter scanning analysis with report only
• 93227 — Holter physician review and interpretation only
• 93228 — External mobile cardiovascular telemetry with ECG recording (MCOT) — up to 30 days, physician review and interpretation per 30 days
• 93229 — MCOT technical support with up to 30 days recording
• 93241–93248 — Extended external ECG monitoring codes for 2–7 day, 7–15 day, and 15–30 day recording periods

Cardiovascular Stress Testing CPT Codes

• 93015 — Cardiovascular stress test — treadmill or bicycle — with continuous ECG monitoring — complete (physician supervision + tracing + interpretation)
• 93016 — Stress test — physician supervision only, without interpretation and report
• 93017 — Stress test — tracing only, without interpretation and report
• 93018 — Stress test — interpretation and report only

Cardiac Catheterization CPT Codes

• 93454 — Catheter placement in coronary artery(s) for coronary angiography, with or without intraprocedural injection for left ventriculography (includes imaging supervision, interpretation and report)
• 93455 — Catheter placement in coronary artery(s) for coronary angiography — with catheter placement in bypass graft(s)
• 93456 — Catheter placement for coronary angiography — with right heart catheterization
• 93457 — Catheter placement for coronary angiography — with right heart catheterization and bypass graft angiography
• 93458 — Left heart catheterization — with coronary angiography and left ventriculography
• 93459 — Left heart catheterization — with coronary angiography, left ventriculography, and bypass graft angiography
• 93460 — Right and left heart catheterization — with coronary angiography and left ventriculography
• 93461 — Right and left heart catheterization — with coronary and bypass graft angiography, and left ventriculography

Critical Modifier Rules for Cardiology Billing

Top Cardiology Billing Errors and Compliance Risks

• Billing global echo (93306) when only the professional component (93306-26) should be billed — happens when cardiologist interprets hospital-based studies without owning the equipment
• Billing stress echo (93351) without also billing the stress test CPT code (93015/93018) — these are separate and distinct services
• Missing prior authorization for diagnostic catheterizations and stress testing — required by most Medicare Advantage and commercial plans
• Bundling violations — billing for services already included in a comprehensive catheterization code
• Incorrect place of service — hospital-based services billed with an office place of service code, or vice versa
• Not billing the separate Holter interpretation code when the recording device was supplied by a third party
• Upcoding echo studies from 93308 (limited) to 93306 (complete) without documentation supporting a complete study

How HNA Supports Cardiology Practices

HNA's cardiology billing specialists understand every CPT code, modifier rule, and payer-specific coverage policy for cardiac services. We conduct quarterly coding audits for all cardiology clients to identify patterns before they become compliance issues, and our clients consistently achieve 98%+ first-pass claim rates for cardiology services.