• Brenton M Wong, Jeffrey J Perry, Wei Cheng, Bo Zheng, Kevin Guo, Monica Taljaard, Allan C Skanes, and Ian G Stiell.
• Department of Emergency Medicine, University of Ottawa, Ottawa, ON, Canada.
• CJEM. 2021 Jul 1; 23 (4): 500511500-511.

BackgroundRecent studies have presented concerning data on the safety of cardioversion for acute atrial fibrillation and flutter. We conducted this meta-analysis to evaluate the effect of oral anticoagulation use on thromboembolic events post-cardioversion of low-risk acute atrial fibrillation and flutter patients of < 48 h in duration.MethodsWe searched MEDLINE, Embase, and Cochrane from inception through February 6, 2020 for studies reporting thromboembolic events post-cardioversion of acute atrial fibrillation and flutter. Main outcome was thromboembolic events within 30 days post-cardioversion. Primary analysis compared thromboembolic events based on oral anticoagulation use versus no oral anticoagulation use. Secondary analysis was based on baseline thromboembolic risk. We performed meta-analyses where 2 or more studies were available, by applying the DerSimonian-Laird random-effects model. Risk of bias was assessed with the Quality in Prognostic Studies tool.ResultsOf 717 titles screened, 20 studies met inclusion criteria. Primary analysis of seven studies with low risk of bias demonstrated insufficient evidence regarding the risk of thromboembolic events associated with oral anticoagulation use (RR = 0.82 where RR < 1 suggests decreased risk with oral anticoagulation use; 95% CI 0.27 to 2.47; I2 = 0%). Secondary analysis of 13 studies revealed increased risk of thromboembolic events with high baseline thromboembolic risk (RR = 2.25 where RR > 1 indicates increased risk with higher CHADS2 or CHA2DS2-VASc scores; 95% CI 1.25 to 4.04; I2 = 0%).ConclusionPrimary analysis revealed insufficient evidence regarding the effect of oral anticoagulation use on thromboembolic events post-cardioversion of low-risk acute atrial fibrillation and flutter, though the event rate is low in contemporary practice. Our findings can better inform patient-centered decision-making when considering 4-week oral anticoagulation use for acute atrial fibrillation and flutter patients.

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