Optimizing Energy Delivery in Cardioversion: A Randomized PROTOCOLENERGYTrial of 2 Different Algorithms in Patients With Atrial Fibrillation.

Background: The optimal energy protocol for direct current cardioversion of atrial fibrillation remains uncertain. The Rational vs Maximum Fixed Energy (PROTOCOLENERGY) randomized trial compared a stepwise escalating energy algorithm (RaA, 150 J, 360 J, and 360 J) with a maximum fixed energy algorithm (MfA, 3 x 360 J).

Methods: In a 1:1 randomized trial, 300 patients with atrial fibrillation received biphasic discharges via hand-held paddles in the anterolateral position. Primary endpoints were sinus rhythm at 1 minute and neurologic complications at 2 hours; secondary endpoints included sinus rhythm at 2 hours, skin changes and chest discomfort at 24 hours.

Results: Sinus rhythm at 1 minute was achieved in 92.7% of RaA and 94.0% of MfA patients (P = 0.643) and maintained at 2 hours in 91.3% of both groups. There were no neurologic complications. The protocols differed significantly after the first shock (72.7% in RaA vs 83.3% in MfA; P = 0.026) but equalized after subsequent maximum energy shocks. Fewer RaA patients experienced skin redness compared with MfA patients (19.3% vs 36.0%, P = 0.001), which was attributed to the lower initial 150-J shock and total energy delivered (r = 0.243, P < 0.0001). Chest discomfort at 24 hours was not different between groups (P = 0.378). In multivariate analysis, lower body mass index (P < 0.001, cutoff 29 to 34 kg/m) was associated with cardioversion success after the initial 150-J shock.

Conclusions: Both protocols showed similar high cumulative efficacy, but RaA with the initial 150-J shock proved to be beneficial in patients with body mass index less than 29 to 34 kg/m because of fewer skin complications.

Clinical Trial Registration No: NCT05148923.