Serum troponin I level after external electrical direct current synchronized cardioversion in patients with normal or reduced ejection fraction: no evidence of myocytes injury.

BACKGROUND: External electrical cardioversion (EEC) has been suggested as a cause of myocardial damage, but results from several previously published studies are conflicting.

HYPOTHESIS: The purpose of the study was to evaluate myocardial electrical injury caused by EEC.

METHODS: After elective EEC for atrial fibrillation (AF), cardiac troponin I (cTnI) was measured in 193 consecutive patients attending the Cardiology Department of the San Maurizio Hospital of Bolzano for elective EEC of AF over a period of 13 months. External electrical cardioversion was performed by one of the attending cardiologists with a synchronized monophasic defibrillator. Blood sample for cTnI was taken 18-20 h after EEC.

RESULTS: Of 193 patients, 183 (95%) were successfully cardioverted. Mean number of shocks was 1.46 and the mean total energy discharged per procedure was 379.4 +/- 229.2 J. Cardiac troponin remained under the limit of confidence for all patients with a mean value of 0.017 +/- 0.021 mcrg/l. No correlation between total energy delivered and cTnI was found. In the subgroup of patients with low ejection fraction, none had elevated cTnI, and no difference in cTnI values between these and patients with an ejection fraction > 40% was found.

CONCLUSIONS: The results of our analysis indicate that EEC caused no myocardial injury even in patients with low ejection fraction.