How do you cardiovert AF: Drugs or Electricity?

Atrial Fibrillation is the most common arrhythmia we see. Conversion to sinus rhythm of recent-onset of atrial fibrillation is proven to be safe. How do you cardiovert? Is a pharmacological cardioversion first approach more successful than an electrical cardioversion first approach in acute atrial fibrillation?

The RAFF-2 Trial(1) Gives Us the answer.

What They Did

The was a two-protocol trial conducted in 11 academic hospitals in Canada. It compared the safety and efficacy of procainamide + electrical cardioversion (DCCV) vs. DCCV alone. It also looked at the cardioversion group and looked to assess the best pad positions.

There were two protocols used:

• Protocol 1: IV procainamide 15mg/kg (max dose 1500mg) given over 30 minutes followed by electrical cardioversion (up to 3 shocks at > 200J), vs placebo and shock
• Protocol 2: Those patients that needed a shock in protocol m1 they compared anterolateral vs anteroposterior pad positions.

This was not an emergency department study. Patients were included if they had atrial fibrillation for at least 3 hours, had a clear onset within 48 hours, or within 7 days of arrival and had 4 weeks of anticoagulation, or had a TOE showing no left atrial thrombus.

What they found

52% of patients converted to normal sinus rhythm with procainamide alone in the drug and shock group vs 9% in the shock alone group.

The conversion to normal sinus rhythm was similar in the drug and shock vs shock alone group (96% vs 92%)

In those patients that underwent cardioversion anterolateral versus anteroposterior pad placement had similar efficacy ( 94% vs 92%). Most patients converted with one shock.

Adverse events mostly related to transient hypotension in the drug-shock group and hypoxia in the shock group.

My Take on This

Firstly this is not an Emergency Department Study. It included patients with a longer onset of AF. It doesn't mean that it does not apply to what we do, especially as we often see patients who have had anticoagulation for over three weeks, and have gone back into AF, presenting to the ED for cardioversion. In terms of my practice, it reinforces the fact that when I decide to electrically cardiovert, I simply do that and use no pre-cardioversion antiarrhythmics.

Although this trial did not find any difference between pad positioning, the EPIC Trial(2) found that anterior-lateral was superior.

Reference

1. Stiell IG et al. Electrical Versus Pharmacological Cardioversion for Emergency Department Patients with Acute Atrial Fibrillation (RAFF2): A Partial Factorial Randomised Trial. Lancet 2020. PMID: 32007169
2. Schmidt A S. Antero-Lateral Versus Anterior-Posterior Electrode Position for Converting Atrial Fibrillation. Circulation. 2021;144:1995–2003.