SummaryBackground and hypothesis: This study was carried out to determine whether cardiac troponin T test in rapid assay gives positive results in patients previously submitted to cardioversion or electrical defibrillation.Methods: Forty patients with supraventricular tachyarrhythmias lasting no more than 2 days were treated with electrical cardioversion. The total creatine phosphokinase (CPK)-MB isoenzyme and troponin T in rapid assay were measured at baseline and at 6,12, and 24 h thereafter.Results: Total CPK baseline levels were normal in all cases; within 4 h, the serum CPK levels increased by 98%, at 6 h