A randomized, controlled comparison of electrical versus pharmacological cardioversion for emergency department patients with acute atrial flutter.

Background: Acute atrial flutter has one-tenth the prevalence of acute atrial fibrillation in the emergency department (ED) but shares many management strategies. Our aim was to compare conversion from acute atrial flutter to sinus rhythm between pharmacological cardioversion followed by electrical cardioversion (Drug-Shock), and electrical cardioversion alone (Shock-Only).

Methods: We conducted a randomized, blinded, placebo-controlled comparison of attempted pharmacological cardioversion with IV procainamide followed by electrical cardioversion if necessary, and placebo infusion followed by electrical cardioversion. We enrolled stable patients with a primary diagnosis of acute acute atrial flutter at 11 academic EDs. The primary outcome was conversion to normal sinus rhythm.

Findings: From July 2013 to October 2018, we enrolled 76 patients, and none were lost to follow-up. Comparing the Drug-Shock to the Shock-Only group, conversion to sinus rhythm occurred in 33 (100%) versus 40 (93%) (absolute difference 7.0%; 95% CI - 0.6 to 14.6; P = 0.25). Median time to conversion from start of infusion in the Drug-Shock group was 24 min (IQR 21-82) but only 9 (27%) cases were converted with IV procainamide. Patients in both groups had similar outcomes at 14 days; there were no strokes or deaths.

Interpretation: This trial found that the Drug-Shock strategy is potentially superior but that either approach to immediate rhythm control in the ED for patients with acute acute atrial flutter is highly effective, rapid, and safe in restoring sinus rhythm and allowing patients to go home and return to normal activities. Unlike the case of atrial fibrillation, we found that IV procainamide alone was infrequently effective.