Cardioversion of Atrial Fibrillation and Flutter: Comparative Study of Pulsed vs. Low Energy Biphasic Truncated Exponential Waveforms

Abstract

Background: Despite the widespread use of biphasic waveforms for cardioversion and defibrillation, the efficacy and safety of shocks has only been compared in a few studies.

Methods: This retrospective study aims at comparing the efficacy and safety of biphasic truncated exponential (BTE) pulsed energy (PE) waveform with a BTE low energy (LE) waveform for cardioversion of atrial fibrillation (AF) and atrial flutter (AFL). The treatment energies were following an escalating protocol for PE waveform (120-200-200J in AF and 30-120-200J in AFL) and LE waveform (100-200-200J in AF and 30-100-200J in AFL). The protocol was stopped at successful cardioversion (sinus rhythm at 1 minute post-shock), otherwise after the 3rd shock. If the 3rd BTE shock failed, a monophasic shock of 360J was delivered.

Results: From May 2008 to November 2017, 193 patients (153 PE, 40 LE) were included in the study. Both groups significantly differed in a few characteristics, including chest circumference (p<0.05). After adjustment, the success rate was not significantly different for the two waveforms (94.5% PE vs 92.5% LE, Odds Ratio [95% Confidence Interval] = 0.25 [0.03-2.2]).There was no difference in safety: post-shock changes in Hsc-TnI levels were similar (p=0.25). The efficient cumulative energy was particularly related with BSA (β = 131.5, p=0.05), AF/AFL duration (β = 0.24, p=0.01) and gender (β = 61.8, p=0.05).

Conclusions: The major clinical implications of this study concern the high success rate of cardioversion with both biphasic pulses and no superiority of LE over PE waveform with an excellent safety profile without post-shock myocardial injuries.

Keywords: Atrial fibrillation; Biphasic waveforms; Cardioversion; Low energy; Pulsed energy.

Figure 2.. Waveforms of PE (top trace) and LE (bottom trace) recorded during ECV interventions with energy setting of 200J and a patient impedance of 75Ω. Below, the escalating energy protocol applied at 1st-2nd-3rd shocks for both waveforms.

Figure 1.. CONSORT flow diagram showing the patient allocation groups.

Figure 3.. Cumulative success rate versus cumulative selected energy for patients treated with PE waveform (N=153) and patients treated with LE waveform (N=40). Results for AF and AFL patients are combined.