Anterior-lateral Vs Anterior-posterior Electrode Positioning for Cardioversion of Atrial Fibrillation and Atrial Arrhythmias: A Systematic Review and Meta-analysis Introduction: Multiple randomized controlled trials (RCTs) have compared the efficacy of anterolateral (AL) and anteroposterior (AP) electrode positioning for cardioversion of atrial fibrillation and other atrial arrhythmias with conflicting results. We hypothesized that AP electrode positioning will have a superior efficacy for cardioversion due to better alignment of the energy vector with the atria. Methods: A systematic search was conducted in the MEDLINE and Embase databases utilizing the Ovid interface. Results were screened to identify RCTs comparing AL and AP position of electrodes for cardioversion for atrial arrhythmias. Studied outcomes included the success of cardioversion, number of shocks, and mean shock energy required for successful cardioversion to sinus rhythm. Mantel-Haenszel aggregated risk ratios (RR) with 95% CIs were calculated. Results: A total of 14 RCTs were included comprising 2445 patients (1329 AL, 1116 AP). There was no statistically significant difference between the two groups with respect to successful cardioversion (RR 1.02 [0.97-1.06]; p = 0.43), first shock success (RR 1.14 [0.99-1.32]; p = 0.06), second shock success (RR1.08 [0.94-1.23]; p = 0.29), mean shock energies (mean difference 6.49 [17.33-30.31]; p = 0.59). We additionally compared success at high; >150 J (RR 1.02 [0.92-1.14] and low; <150 J (RR 1.09 [0.97-1.22]; p = 0.64) cardioversion energies which also did not show any significant difference. Conclusions: There is no significant difference in the efficacy between AL vs. AP electrode position for cardioversion of atrial arrhythmias.