Efficacy and safety of ambulatory electric cardioversion of atrial fibrillation with monophasic and biphasic shock

BACKGROUND: The aim of this study was to evaluate the safety and efficacy of ambulatory external cardioversion (EC) by means of monophasic and biphasic shock in patients with persistent atrial fibrillation (AF). METHODS: One hundred and twenty-seven consecutive patients with AF were submitted to EC, preceded by short general anesthesia with propofol, after pretreatment with oral anticoagulants for at least 3 weeks and, if not contraindicated, with amiodarone. In 87 of these patients we used monophasic shock and in 40 patients we used biphasic shock. Our protocol provided for up to 3 shocks delivered at an energy level ranging between 200 and 360 J for monophasic and from 70 to 175 J for biphasic shock. The patients were discharged after 4 hours of ECG monitoring and following a determination of serum CK-MB at the fourth hour. RESULTS: The mean age of the patients submitted to EC with monophasic and biphasic shock (65 +/- 9 vs 67 +/- 7 years) and the duration of AF (34 +/- 22 vs 32 +/- 25 days) were similar. The efficacy of EC with monophasic shock was 85% and the mean energy delivered was 266 +/- 81.5 J. The efficacy of the EC with biphasic shock was 98% and the mean energy delivered was 127 +/- 40 J. The difference between the percentage of efficacy and the number of joules delivered was statistically significant (p < 0.05). The mean value of the CK-MB after 4 hours following delivery of the shock was not significantly different: 2.5 ng/ml for monophasic vs 1.7 ng/ml for biphasic shock (p = NS). CONCLUSIONS: In our patients, ambulatory EC of persistent AF is safe and feasible; biphasic shock is more efficacious and requires less energy with respect to monophasic shock.