Cardiology ICD-10 Codes & CPT Codes

Accurate cardiology coding is critical for reimbursement and compliance. This reference covers the most-used ICD-10-CM diagnosis codes and CPT procedure codes for cardiology practices in the United States. Whether you are billing for hypertension management, echocardiography, or arrhythmia treatment, these codes reflect current CMS guidelines and are updated for the 2025-2026 fiscal year.

FY 2026 ICD-10-CM (CMS) · CPT codes updated annually · All codes verified billable · Last verified: June 2026

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Top ICD-10 Codes for Cardiology

ICD-10 Code Description Billable
I10 Essential (primary) hypertension
I25.10 Atherosclerotic heart disease of native coronary artery w/o angina
I25.9 Chronic ischemic heart disease, unspecified
I48.91 Unspecified atrial fibrillation
I48.0 Paroxysmal atrial fibrillation
I50.9 Heart failure, unspecified
I50.22 Chronic systolic (congestive) heart failure
I21.9 Acute myocardial infarction, unspecified
I20.9 Angina pectoris, unspecified
I42.9 Cardiomyopathy, unspecified
I44.2 Atrioventricular block, complete
I47.2 Ventricular tachycardia
I49.9 Cardiac arrhythmia, unspecified
I35.0 Nonrheumatic aortic (valve) stenosis
I11.9 Hypertensive heart disease without heart failure
R00.0 Tachycardia, unspecified
R00.1 Bradycardia, unspecified
R07.9 Chest pain, unspecified
Z95.0 Presence of cardiac pacemaker
Z82.49 Family history of ischemic heart disease and other diseases of the circulatory system
I21.01 ST elevation myocardial infarction of left anterior descending coronary artery
I21.11 ST elevation myocardial infarction of right coronary artery
I21.4 Non-ST elevation (NSTEMI) myocardial infarction
I25.110 Atherosclerotic heart disease of native coronary artery with unstable angina
I25.2 Old myocardial infarction
I26.09 Other pulmonary embolism without acute cor pulmonale
I27.0 Primary pulmonary hypertension
I27.20 Pulmonary hypertension, unspecified
I30.9 Acute pericarditis, unspecified
I31.9 Disease of pericardium, unspecified
I33.0 Acute and subacute infective endocarditis
I34.0 Nonrheumatic mitral valve insufficiency
I38 Endocarditis, valve unspecified
I43 Cardiomyopathy in diseases classified elsewhere
I45.10 Unspecified right bundle-branch block
I46.9 Cardiac arrest, cause unspecified
I48.19 Other persistent atrial fibrillation
I48.20 Chronic atrial fibrillation, unspecified
I50.1 Left ventricular failure, unspecified
I50.32 Chronic diastolic congestive heart failure
I63.9 Cerebral infarction, unspecified
I70.201 Unspecified atherosclerosis of native arteries of extremities, right leg
I73.9 Peripheral vascular disease, unspecified
I77.1 Stricture of artery
Z87.39 Personal history of other endocrine, nutritional and metabolic diseases

Source: CMS ICD-10-CM Official Code Set FY 2026

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Common CPT Codes for Cardiology Billing

CPT Code Description Medicare Rate* Common Modifiers
93000 ECG, routine with at least 12 leads; with interpretation and report ~$15.90 -26, -TC
93306 Echocardiography, transthoracic, real-time with image documentation ~$225.40 -26, -TC, -52
93017 Cardiovascular stress test using maximal or submaximal treadmill or bicycle exercise ~$64.80 -26, -TC
93010 ECG, routine; interpretation and report only ~$10.50 -26
93880 Duplex scan of extracranial arteries; complete bilateral study ~$148.20 -26, -TC
99213 Office outpatient visit, established patient, low complexity ~$77.50 -25, -95
99214 Office outpatient visit, established patient, moderate complexity ~$111.90 -25, -95
93015 Cardiovascular stress test; complete procedure ~$114.70 N/A (facility-only)
93018 Cardiovascular stress test; interpretation and report only ~$50.10 -26
93025 Microvolt T-wave alternans for ventricular arrhythmia assessment ~$138.60 -26, -TC
93040 Rhythm ECG, 1-3 leads; with interpretation and report ~$19.80 -26
93224 External electrocardiographic recording up to 48 hours, interpretation ~$95.40 -26, -TC
93270 External patient and auto-activated ECG recording, 30 days ~$81.20 -26
93600 Bundle of His recording ~$N/A (facility) N/A
93620 Comprehensive electrophysiologic evaluation with induction ~$N/A (facility) N/A
93653 EP eval with ablation of arrhythmia focus ~$N/A (facility) N/A
93798 Outpatient cardiac rehabilitation physician services ~$54.30 -GP

*Approximate 2025 CMS national non-facility rate. Rates vary by geography, setting, and payer contract. Refer to the CMS Physician Fee Schedule for official rates.

Top Denial Reasons for Cardiology Claims

Medical Necessity Not Documented

Cardiology procedures such as stress tests and echocardiograms require documented symptoms or risk factors supporting clinical indication. Ensure the referring diagnosis clearly links the procedure to the patient presenting complaint in the medical record.

Missing or Incorrect Modifier

High-volume cardiology codes like 93306 and 93017 are frequently denied when the -26 (professional component) or -TC (technical component) modifier is omitted or reversed. Verify that the billing entity matches the modifier submitted before claim submission.

Prior Authorization Not Obtained

Many payers require prior authorization for advanced cardiac imaging, electrophysiology studies, and cardiac catheterizations. Check payer-specific authorization requirements and obtain written approval before scheduling elective procedures.

Diagnosis-Procedure Code Mismatch

Claims are denied when the ICD-10 diagnosis does not support the CPT procedure billed, such as submitting a routine ECG code without a supporting cardiac diagnosis. Cross-check NCCI edits and LCD policies to ensure diagnosis and procedure pairing is compliant.

Cardiology Billing & Coding Tips

  • Always specify laterality and acuity in MI coding — I21 codes differ by STEMI/NSTEMI and vessel site.
  • Atrial fibrillation has four billable subtypes (I48.0–I48.19, I48.2x, I48.91); query the physician before defaulting to I48.91.
  • Document the causal relationship explicitly when coding hypertensive heart disease (I11.x) to satisfy CMS medical necessity.
  • 93306 (echo) requires a separate interpretation report signed by the cardiologist to be billable under Part B.

Frequently Asked Questions

What is the ICD-10 code for atrial fibrillation?

The most common code is I48.91 (Unspecified atrial fibrillation). However, coders should specify the type when documented: I48.0 (Paroxysmal), I48.11/I48.19 (Persistent), I48.20/I48.21 (Chronic/Long-standing persistent), or I48.11 (Longstanding persistent).

Is I10 (essential hypertension) billable?

Yes. I10 is a valid, billable ICD-10-CM code. It is the primary diagnosis for essential (primary) hypertension and is accepted by all major payers.

What CPT code is used for an EKG?

93000 covers a routine ECG with interpretation and report. Use 93010 if you are only providing the interpretation (reading only, no tracing performed at your site).

How does OmniMD help with cardiology coding?

OmniMD’s Cardiology EHR embeds ICD-10 and CPT code suggestions directly into the encounter workflow, reducing manual lookup time and claim denial rates.

What is the difference between I25.10 and I25.9?

I25.10 specifies atherosclerotic heart disease of a native coronary artery without angina pectoris. I25.9 is a less-specific chronic ischemic heart disease code. Always code to the highest specificity supported by the documentation.

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