Pharmacologic cardioversion followed by electrical cardioversion and electrical cardioversion only were found to be safe and effective in patients presenting to the emergency department (ED) with recent onset acute atrial fibrillation (AF), according to a study published in The Lancet.

Although AF is the most common dysrhythmia observed in EDs, there is wide variation in treatment practices among emergency room physicians and few studies in which electrical cardioversion alone or in combination with pharmacologic conversion has been examined.

In this Canadian multicenter partial factorial randomized trial ( identifier: NCT01891058), 396 patients with AF (mean age, 60 years; 66% men; 68% with history of AF) who visited 1 of 11 EDs were enrolled between July 2013 and October 2018.

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In the study, 2 different protocols were used. Protocol 1 was a blinded randomized placebo-controlled trial in which 2 treatments were compared: AF treatment with pharmacologic cardioversion (intravenous procainamide infusion, 15 mg/kg over 30 minutes) followed by electrical cardioversion (≤3 shocks at ≥200 J) vs treatment with a saline placebo infusion followed by electrical cardioversion (shock-only group).

In patients requiring electrical cardioversion, protocol 2 was used; protocol 2 was a secondary open-label randomized nested comparison of 2 different pad placements: anteroposterior vs anterolateral, with randomization occurring 30 minutes after unsuccessful chemical conversion.

The primary outcome was the conversion rate to normal sinus rhythm (NSR) for ≥30 minutes at any point post-randomization to immediately after the third shock. Secondary outcomes included NSR conversion for each pad placement and occurrence of adverse events (AEs).

There were 204 participants in the drug-shock group (mean age, 60.0±15.1 years; 66% men; mean AF duration, 14.3 hours) and 192 participants in the shock-only group (mean age, 60.1±14.8 years; 66% men; mean AF duration, 16.8 hours). There were comparable percentages of patients converting to NSR (drug-shock group: n=196; 96%; shock-only group: n=176; 92%; absolute difference, 4%; 95% CI, 0-9; P =.066). Discharge rates were also comparable in the 2 groups (drug-shock group: n=198; 97%; shock-only group: n=183; 95%; absolute difference, 2%; 95% CI, −2 to 6; P =.36). In the drug-shock group, 106 participants (52%) converted to NSR after pharmacologic cardioversion, obviating the need for electrical shock.

There were comparable percentages of conversion to NSR for the 2 pad positions (anterolateral placement, 94%; anteroposterior placement, 92%; relative risk, 1.01; 95% CI, 0.95-1.09; P =.68). There were no serious AEs reported during follow-up. The odds ratio for conversion to NSR was 2.16 (95% CI, 0.88-5.28; P =.091) in the drug-shock group.

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“The most important finding from this study is that either approach to immediate rhythm control in the emergency department leads to a very high proportion of patients being discharged in sinus rhythm without serious adverse events,” noted the authors. They recommended that future research involve larger sample sizes and investigation of cardioversion safety without anticoagulation.


Stiell IG, Sivilotti MLA, Taljaard M, et al. Electrical versus pharmacological cardioversion for emergency department patients with acute atrial fibrillation (RAFF2): a partial factorial randomised trial. Lancet. 2020;395(10221):339-349. doi:10.1016/s0140-6736(19)32994-0

This article originally appeared on The Cardiology Advisor