A36.81

HCC Category Mapping

What This Code Means

This is a serious heart muscle infection caused by diphtheria bacteria that weakens the heart's ability to pump blood effectively. It occurs when diphtheria toxin damages the heart tissue, potentially leading to heart failure or irregular heartbeats.

Coding Tips

• •This code should only be used when diphtheria has been confirmed and documented as causing cardiomyopathy; do not code presumptively
• •Verify that the primary diphtheria diagnosis (A36.x) is also coded separately, as A36.81 is a manifestation code that requires the underlying diphtheria condition to be reported

Clinical Significance

Diphtheritic cardiomyopathy is a life-threatening cardiac complication of Corynebacterium diphtheriae infection, caused by diphtheria toxin damaging the myocardium. It can lead to heart failure, conduction abnormalities, and sudden death. This complication typically occurs 1-2 weeks after onset of pharyngeal diphtheria and is a major cause of diphtheria-related mortality.

Documentation Requirements

• ✓Confirmed or suspected diphtheria infection with cardiac involvement
• ✓Echocardiogram showing ventricular dysfunction or wall motion abnormalities
• ✓ECG findings (conduction delays, ST-T changes, arrhythmias)
• ✓Cardiac biomarkers (troponin, BNP/NT-proBNP) documenting myocardial injury
• ✓Timeline correlation between diphtheria onset and cardiac symptoms

Commonly Confused Codes