Written by Sam Parnell
There was no significant difference in overall rate of conversion from atrial fibrillation (a-fib) to normal sinus rhythm with procainamide infusion followed by electrical cardioversion, if needed, compared to placebo infusion followed by electrical cardioversion.
Why does this matter?
A-fib is the most common arrhythmia diagnosed in the emergency department. Management is usually centered on rate or rhythm control as well as consideration for anticoagulation to reduce the risk of thrombosis and stroke. Rhythm control can be accomplished with pharmacologic or electrical cardioversion, and there is significant practice variation for how to best cardiovert patients with acute atrial fibrillation. RACE 7 raised the question of whether early cardioversion was needed at all.
Drug-shock or just shock?
This was a randomized, blinded, placebo-controlled, clinical trial of 396 patients with acute a-fib across 11 academic EDs in Canada. Patients were randomized for attempted cardioversion with IV procainamide (15 mg/kg over 30 min) followed by electrical cardioversion (drug-shock), if necessary, or placebo infusion followed by electrical cardioversion (shock-only). For patients having electrical cardioversion, there was an additional randomized, open-label, nested comparison of anteroposterior versus anterolateral pad positions.
Most patients were successfully cardioverted (96% in the drug-shock group vs 92% in the shock-only group; p=0.07) and discharged home (97% in the drug-shock group vs 95% in the shock-only group; p=0.60), with no significant difference between the groups. 52% of patients in the drug–shock group converted after procainamide infusion only. No patients had serious adverse events at follow up. In addition, there was no significant difference in rate of electrical cardioversion with anterolateral or anteroposterior pad placement (94% anterolateral vs 92% of anteroposterior; p=0.68).
The drug-shock and shock-only strategies both appear to be highly effective, rapid, and safe methods to achieve rhythm control in a-fib. However, pharmacologic cardioversion worked for approximately half of patients and avoided the procedural sedation needed for electrical cardioversion. Therefore, procainamide infusion may be a better initial choice for cardioversion, especially for patients with first episodes of atrial fibrillation and for patients younger than 70 years of age.
Electrical versus pharmacological cardioversion for emergency department patients with acute atrial fibrillation (RAFF2): a partial factorial randomised trial. Lancet. 2020 Feb 1;395(10221):339-349. doi: 10.1016/S0140-6736(19)32994-0.
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