SGEM#267: Afib of the Night – Chemical vs. Electrical First Cardioversion

Date: September 18th, 2019 Reference: Scheuermeyer et al. A Multicenter Randomized Trial to Evaluate a Chemical-first Cardioversion Strategy for Patients with Uncomplicated Acute Atrial Fibrillation. AEM Sept 2019 Guest Skeptic: Dr. Chris Bond is an emergency medicine physician and clinical lecturer in Calgary. He is also an avid FOAM supporter/producer through various online outlets including TheSGEM. Case: A 55-year-old male presents to the emergency department with sudden onset of palpitations and pre-syncope starting one hour ago. He has no chest pain or shortness of breath and aside from a heart rate of 140 beats per minute, the rest of his vital signs appear within normal limits. His past medical history is significant for hypertension for which he takes perindopril. His ECG shows atrial fibrillation with a rapid ventricular response. Background: Atrial fibrillation is the most commonly encountered significant dysrhythmia in the emergency department (1). We have covered this topic a number of times on the SGEM. SGEM#88: Shock Through the Heart (Ottawa Aggressive Atrial Fibrillation Protocol) SGEM#133: Just Beat It (Atrial Fibrillation) with Diltiazem or Metoprolol? SGEM#222: Rhythm is Gonna Get You – Into an Atrial Fibrillation Pathway SGEM#260: Quit Playing Games with My Heart – Early or Delayed Cardioversion for Recent Onset Atrial Fibrillation? The most recent episode looked at whether late cardioversion is non-inferior to early cardioversion (SGEM#260) in acute atrial fibrillation. The SGEM bottom line from that episode was that the late approach was non-inferior to early approach and that both strategies achieve high rates of sinus rhythm at the 4-week follow up (>90%). In uncomplicated patients with symptoms less than 48 hours and no stroke or TIA in the past six months, the 2018 Canadian Cardiovascular Society (CCS) guidelines permit rate or rhythm control (2). There is significant variability in the management of patients with acute atrial fibrillation, with the proportion undergoing rhythm control ranging from 42-85% in Canadian academic centres (3). The rhythm control strategies typically employed are chemical cardioversion with procainamide infusion or electrical cardioversion with electrical countershock (3-6). Both of these strategies appear safe from prior studies, but comparative effectiveness data is lacking. Thus, Canadian management varies, with 56% of patients receiving a chemical-first approach and 44% an electrical-first approach (3). Clinical Question: In emergency department patients with atrial fibrillation, is sinus rhythm achieved more rapidly with electrical-first rhythm control when compared with chemical-first rhythm control? Reference: Scheuermeyer et al. A Multicenter Randomized Trial to Evaluate a Chemical-first Cardioversion Strategy for Patients with Uncomplicated Acute Atrial Fibrillation. AEM Sept 2019 Population: Adults between 18 and 75 years of age with atrial fibrillation less than 48 hours duration and a CHADS2 score less than two. Excluded: Hemodynamic instability, atrial flutter, CHADS2 score greater than or equal to two, patients with an acute underlying medical illness, recent cardiac procedure, acute intoxication or withdrawal from alcohol or illicit substances. They also excluded those who attended the emergency department for other reasons (eg. trauma, gout) who were incidentally found to be in atrial fibrillation. Intervention: Chemical cardioversion with procainamide (a dose of 17mg/kg up to a maximum of 1500mg infused over one hour was recommended). This was followed by electrical cardioversion if chemical cardioversion was unsuccessful. Comparison: Electrical cardioversion using a synchronized biphasic waveform sequence of 100J to 150J to 200J to a maximum of three shocks were allowed. Patients were sedated at the physicians’ discretion. The study recommended an initial propofol bolus of 0.