I43
BillableCardiomyopathy in diseases classified elsewhere
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is I43 an HCC code?
Yes. I43 maps to Cardiomyopathy/Myocarditis 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 I43
For I43to 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 I43 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
I43 is the ICD-10-CM diagnosis code for cardiomyopathy in diseases classified elsewhere. This code is used when the heart muscle becomes weakened or enlarged as a result of another disease or condition that the patient has. It indicates that cardiomyopathy (a problem with the heart's pumping ability) is secondary to another underlying medical condition rather than being a primary heart disease. I43 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering other forms of heart disease (i30-i5a).
Under the CMS-HCC V28 risk adjustment model, I43 maps to Cardiomyopathy/Myocarditis (HCC 227) with a community, non-dual, aged base RAF weight of 0.189. Under the older CMS-HCC V24 model, I43 maps to Congestive Heart Failure (HCC 85) with a community, non-dual, aged base RAF weight of 0.331. 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.
This is a secondary diagnosis code that requires documentation of the underlying disease causing the cardiomyopathy; always code the primary condition first. Because I43 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 I43 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a secondary diagnosis code that requires documentation of the underlying disease causing the cardiomyopathy; always code the primary condition first
- •Do not use this code for primary cardiomyopathy (I42.-); verify the causal relationship between the documented disease and cardiomyopathy is clearly stated in the medical record
Clinical Significance
Cardiomyopathy in diseases classified elsewhere is a manifestation code indicating that heart muscle disease has developed secondary to another primary condition. Common underlying causes include thyrotoxicosis, hemochromatosis, and metabolic disorders. This code captures the cardiac consequence of systemic disease and must always be paired with the underlying etiology code.
Documentation Requirements
- ✓Provider diagnosis of cardiomyopathy as a manifestation of another disease
- ✓Underlying primary disease documented and coded first
- ✓Causal relationship between the primary disease and cardiomyopathy explicitly stated
- ✓Echocardiographic or other evidence of cardiac dysfunction
- ✓Documentation that the cardiomyopathy is secondary, not primary
Excludes 1 — Do NOT code together
Code First
Commonly Confused Codes
- •I42.0-I42.9 — Primary cardiomyopathy codes; use for primary heart muscle disease, not secondary
- •I42.7 — Cardiomyopathy due to drug and external agent; for external causes, not underlying diseases
- •I42.6 — Alcoholic cardiomyopathy; specific etiology with its own code
- •I42.8 — Other cardiomyopathies; for primary cardiomyopathies not otherwise classified