ICD-10 Code A36.81 – Diphtheritic Cardiomyopathy (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A36.81 – Diphtheritic cardiomyopathy
What it is
A36.81 identifies cardiomyopathy caused by diphtheria toxin. Use it when the heart muscle is affected as a complication of diphtheria, not for unrelated cardiac disease.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include arrhythmia, heart failure, or myocardial dysfunction occurring in the setting of diphtheria.
When to use this code
Use this code when the provider documents diphtheritic involvement of the myocardium or cardiomyopathy due to diphtheria. It may also fit cases where cardiac complications are clearly linked to active or recent diphtheria infection. Check documentation for the causal relationship.
Do not use for
Do not use it for cardiomyopathy without diphtheria, or for nonspecific myocarditis and cardiac symptoms alone. If the record does not support diphtheritic cause, code the documented condition instead.
Coding tip
Confirm both the diphtheria diagnosis and the cardiac complication in the record before assigning A36.81.