A randomized trial comparing monophasic and biphasic waveform shocks for external cardioversion of atrial fibrillation

Background We compared efficacy of and pain felt after biphasic truncated exponential (BTE) and monophasic damped sine (MDS) shocks in patients undergoing external cardioversion of atrial fibrillation (AF). Methods Patients with AF were randomized to BTE or MDS waveform cardioversion. Successive shocks were delivered at 70, 100, 200, and 360 J until successful cardioversion, with one 360 J attempt of the alternate waveform when all 4 shocks failed. Success was determined by blinded over-read of electrocardiograms. Peak current was calculated from energy and impedance. Patients rated their pain at 1 and 24 hours after cardioversion. Results Fourteen of 37 (38%) patients treated with MDS and 34 of 35 (97%) treated with BTE shocks were cardioverted at less than or equal to200 J (P < .0001). Success rates of MDS versus BTE shocks were 5.4% versus 60% for 70 J, 19% versus 80% for ≤100 J, and 86% versus 97% for ≤360 J. BTE shocks cardioverted with less peak current (14.0 ± 4.3 vs 39.5 ± 11.2 A, P < .0001), less energy (97 +/- 47 vs 278 +/- 120 J, P < .0001), and less cumulative energy (146 ± 116 vs 546 ± 265 J, P < .0001). Patients felt less pain after BTE than MDS shocks at 1 hour (P < .0001) and 24 hours (P < .0001) after cardioversion. Conclusion This BTE waveform is superior to the MDS waveform for cardioversion of AF, requiring much less energy and current, and causing less postprocedural pain.