B33.24
BillableViral cardiomyopathy
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is B33.24 an HCC code?
Yes. B33.24 maps to Cardiomyopathy under the CMS-HCC V28 risk adjustment model (and Congestive Heart Failure under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for B33.24
For B33.24 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed B33.24 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
B33.24 is the ICD-10-CM diagnosis code for viral cardiomyopathy. Viral cardiomyopathy is weakening of the heart muscle caused by a viral infection, which reduces the heart's ability to pump blood throughout the body. B33.24 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering other viral diseases (b25-b34).
Under the CMS-HCC V28 risk adjustment model, B33.24 maps to Cardiomyopathy (HCC 227) with a community, non-dual, aged base RAF weight of 0.339. Under the older CMS-HCC V24 model, B33.24 maps to Congestive Heart Failure (HCC 85) with a community, non-dual, aged base RAF weight of 0.368. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Document the ejection fraction or functional class if available to indicate severity. Because B33.24 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for B33.24 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the ejection fraction or functional class if available to indicate severity
- •Specify if this is acute or chronic cardiomyopathy, as this affects treatment and prognosis
Clinical Significance
Viral cardiomyopathy is heart muscle disease caused by viral infection, most commonly coxsackievirus B, adenovirus, or parvovirus B19. It is a leading cause of dilated cardiomyopathy in younger patients and can progress to heart failure requiring transplant. Accurate capture reflects both the infectious etiology and the cardiac dysfunction burden.
Documentation Requirements
- ✓Viral etiology confirmed or strongly suspected (endomyocardial biopsy with viral PCR, or clinical diagnosis with supporting serology)
- ✓Echocardiographic findings: left ventricular ejection fraction, chamber dimensions, wall motion abnormalities
- ✓Heart failure classification if applicable (NYHA class I-IV)
- ✓Specific virus identified if known (coxsackievirus, adenovirus, parvovirus, influenza, SARS-CoV-2)
- ✓Treatment plan: heart failure medications, activity restrictions, cardiac monitoring
Commonly Confused Codes
- •I42.0 (Dilated cardiomyopathy) — Idiopathic or non-infectious dilated cardiomyopathy; B33.24 specifies viral etiology
- •I40.0 (Infective myocarditis) — Acute myocarditis is inflammation; cardiomyopathy implies structural/functional changes that may persist after acute inflammation resolves
- •I25.5 (Ischemic cardiomyopathy) — Heart muscle disease from coronary artery disease, not viral infection