A Multicenter Randomized Trial to Evaluate a Chemical-first or Electrical-first Cardioversion Strategy for Patients With Uncomplicated Acute Atrial Fibrillation

Acad Emerg Med. 2019 Sep;26(9):969-981. doi: 10.1111/acem.13669. Epub 2019 Aug 19.


Background: Emergency department (ED) patients with uncomplicated atrial fibrillation (AF) of less than 48 hours may be safely managed with rhythm control. Although both chemical-first and electrical-first strategies have been advocated, there are no comparative effectiveness data to guide clinicians.

Methods: At six urban Canadian centers, ED patients ages 18 to 75 with uncomplicated symptomatic AF of less than 48 hours and CHADS2 score of 0 or 1 were randomized using concealed allocation in a 1:1 ratio to one of the following strategies: 1) chemical cardioversion with procainamide infusion, followed by electrical countershock if unsuccessful; or 2) electrical cardioversion, followed by procainamide infusion if unsuccessful. The primary outcome was the proportion of patients discharged within 4 hours of arrival. Secondary outcomes included ED length-of-stay (LOS); prespecified ED-based adverse events; and 30-day ED revisits, hospitalizations, strokes, deaths, and quality of life (QoL).

Results: Eighty-four patients were analyzed: 41 in the chemical-first group and 43 in the electrical-first group. Groups were balanced in terms of age, sex, vital signs, and CHADS2 scores. All patients were discharged home, with 83 (99%) in sinus rhythm. In the chemical-first group, 13 of 41 patients (32%) were discharged within 4 hours compared to 29 of 43 patients (67%) in the electrical-first group (p = 0.001). In the chemical-first group, the median ED LOS was 5.1 hours (interquartile range [IQR] = 3.5 to 5.9 hours) compared to 3.5 hours (IQR = 2.4 to 4.6 hours) in the electrical-first group, for a median difference of 1.2 hours (95% confidence interval = 0.4 to 2.0 hours, p < 0.001). No patients experienced stroke or death. All other outcomes, including adverse events, ED revisits, and QoL, were similar.

Conclusion: In uncomplicated ED AF patients managed with rhythm control, chemical-first and electrical-first strategies both appear to be successful and well tolerated; however, an electrical-first strategy results in a significantly shorter ED LOS.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Anti-Arrhythmia Agents / administration & dosage*
  • Atrial Fibrillation / therapy*
  • Canada
  • Electric Countershock / methods*
  • Emergency Service, Hospital
  • Female
  • Humans
  • Length of Stay / statistics & numerical data
  • Male
  • Middle Aged
  • Procainamide / administration & dosage*
  • Quality of Life
  • Young Adult


  • Anti-Arrhythmia Agents
  • Procainamide

Grant support