Anterior–Lateral Versus Anterior–Posterior Electrode Position for Cardioverting Atrial Fibrillation

Abstract

Background: Smaller randomized studies have reported conflicting results regarding the optimal electrode position for cardioverting atrial fibrillation. However, anterior-posterior electrode position is widely used as a standard and believed to be superior to anterior-lateral electrode position. Therefore, we aimed to compare anterior-lateral and anterior-posterior electrode position for cardioverting atrial fibrillation in a multicenter randomized trial. Methods: In this multicenter, investigator-initiated, open-label trial, we randomly assigned patients with atrial fibrillation scheduled for elective cardioversion to anterior-lateral or anterior-posterior electrode position. The primary outcome was the proportion of patients in sinus rhythm after the first shock. The secondary outcome was the proportion of patients in sinus rhythm after up to four shocks escalating to maximum energy. Safety outcomes were any cases of arrhythmia during or after cardioversion, skin redness, and patient-reported peri-procedural pain. Results: We randomized 468 patients. The primary outcome occurred in 126 patients (54%) assigned to anterior-lateral electrode position and in 77 patients (33%) assigned to anterior-posterior electrode position, a risk difference of 22 percentage-points, 95%-confidence interval: 13-30, P<0.001. The number of patients in sinus rhythm after the final cardioversion shock was 216 patients (93%) assigned to anterior−lateral electrode position and 200 patients (85%) assigned to anterior-posterior electrode position, a risk difference of 7 percentage−points, 95%−confidence interval: 2−12. There were no significant differences between groups in any safety outcomes. Conclusions: Anterior-lateral electrode position was more effective than anterior-posterior electrode position for biphasic cardioversion of atrial fibrillation. There were no significant differences in any safety outcome.

Letter by Maqsood et al Regarding Article, “Anterior–Lateral Versus Anterior–Posterior Electrode Position for Cardioverting Atrial Fibrillation”

“…Schmidt et al 1 performed a randomized, multicenter, unblinded study to address optimal electrode pad placement for the cardioversion of atrial fibrillation. In their conclusion, the authors claim that an anterior–lateral electrode configuration is superior to anterior–posterior (A-P) for elective cardioversion of atrial fibrillation.…”

Letter by Ibrahim et al Regarding Article, “Anterior–Lateral Versus Anterior–Posterior Electrode Position for Cardioverting Atrial Fibrillation”

“…Although the trial by Schmidt et al 1 is rigorous and internally valid, it used an escalating energy protocol, which limits its external validity.…”

Response to Letters Regarding Article, “Anterior–Lateral Versus Anterior–Posterior Electrode Position for Cardioverting Atrial Fibrillation”

“…The results of the CHESS trial were not available when we initiated the EPIC trial comparing electrode positions. 3,4 We agree that it would be interesting to study the effect of electrode positions using maximum-fixed energy shocks because it is unknown whether this would have resulted in a different outcome. However, we did escalate the energy settings to maximum energy and found a significant difference between the electrode positions even at this energy setting.…”

“…In our article, we suggest that although anterior–posterior electrode position specifically targets the left atrium, the anterior–lateral electrode position may result in more myocardium cardioverted and provide a more optimal shock vector. 3,5 Therefore, in spite of an observed increased transthoracic impedance at first shock, an optimized shock vector may explain the increased efficacy of anterior–lateral electrode position compared with anterior–posterior electrode position. These clinical observations need further studies to clarify the underlying mechanism.…”