ICD-10 Code I43 – Cardiomyopathy in diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I43 – Cardiomyopathy in diseases classified elsewhere
What it is
I43 identifies cardiomyopathy that is caused by, or occurs as a manifestation of, another underlying disease. You should use it when the heart muscle disorder is not coded as a primary cardiomyopathy.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include heart failure symptoms, reduced cardiac function, or imaging evidence of myocardial disease linked to the underlying condition.
When to use this code
Use I43 when the provider documents cardiomyopathy secondary to another disease, such as a systemic or metabolic disorder, and the record supports a causal relationship. Code the underlying condition first when required by the record and sequencing rules. Check documentation for the specific disease association.
Do not use for
Do not use I43 for primary cardiomyopathies that have their own category, or when the chart only says “cardiomyopathy” without an identified cause. Do not assume causation without provider documentation.
Coding tip
Look for explicit wording such as “due to,” “secondary to,” or “in diseases classified elsewhere” before assigning I43.