Atrial infarction complicating an acute inferior myocardial infarction.

Atrial fibrillation, coronary sinus rhythm, and slow atrial flutter developed in a patient with ECG findings of an acute inferior myocardial infarction. Hemodynamic measurements were suggestive of predominantly right ventricular involvement. A gated cardiac blood pool study demonstrated normal right and left ventricular wall motion with an enlarged, non-contracting right atrium. This led to the antemortem diagnosis of atrial fibrillation.