Objectives: Electrical cardioversion is commonly used to treat patients with atrial fibrillation and atrial flutter to restore normal sinus rhythm. There has been considerable debate as to whether the electrode placement affects the efficacy of electrical cardioversion. The objective of this study was to examine the effectiveness of anteroposterior (A-P) versus anterolateral (A-L) electrode placement to restore normal sinus rhythm.Methods: A search of eight electronic databases, including Medline, EMBASE, CINAHL, and Cochrane was completed. Grey literature (hand-searching, Google, and SCOPUS) searching was also conducted. Studies were included if they were controlled clinical trials comparing the effectiveness of A-P versus A-L pad placement to restore normal sinus rhythm in adult patients with atrial fibrillation and flutter. Two independent reviewers judged study relevance, inclusion, and quality (e.g., risk of bias). Individual and pooled statistics were calculated as relative risks (RRs) with 95% confidence intervals (CIs) using a random-effects model, and heterogeneity (I 2 ) was reported.Results: From 788 citations, 13 studies were included; seven involved monophasic, five involved biphasic, and one analyzed both waveform devices. The included studies tended to report cumulative success rates to restoring normal sinus rhythm after one to five sequential shocks of increasing energy; the number of shocks and energy used differed among studies. The risk of bias of the studies was "unclear." After the first shock, pad placement was not associated with an increased likelihood of restoring normal sinus rhythm (RR = 0.88; 95% CI = 0.73 to 1.06); however, heterogeneity was high (I 2 = 63%). Subgroup comparisons revealed that the A-L position was more effective (RR = 0.77; 95% CI = 0.59 to 1.00) at restoring normal sinus rhythm when using biphasic shocks (comparison p = 0.04). Overall, the pooled results failed to identify a difference between A-P and A-L pad placement in restoring normal sinus rhythm at any time (RR = 1.00; 95% CI = 0.95 to 1.05); however, heterogeneity was high (I 2 = 61%). No significant subgroup differences were found. Side effects were reported in only three studies. Conclusions:The published literature is restricted to persistent atrial fibrillation and atrial flutter, pad placement varied, and energy levels used were lower than currently recommended; however, the accumulated evidence suggests that electrical pad placement is not a critically important factor in successful cardioversion in atrial fibrillation and flutter (AF/AFL). A trial is urgently needed in recentonset atrial fibrillation and atrial flutter patients using biphasic devices and high energy levels to resolve the debate.ACADEMIC EMERGENCY MEDICINE 2014;21:717-726