Comparison of two DCCV algorithms - rational versus maximum fixed energy (PROTOCOLENERGY trial)
Authors: Rucki L , Jiravsky O , Miklik R , Chovancik J , Szmek B , Hrosova M , Ranic I , Spacek R , Neuwirth R , Sknouril L 
Published: May 2024

Abstract

Introduction
Direct current cardioversion (DCCV) is a common procedure used to restore sinus rhythm (SR) in patients with atrial fibrillation (AF). However, there is ongoing debate about the optimal discharge energy to use during DCCV, and there are no clear guidelines on the optimal protocol for selecting the discharge energy.

Purpose
The aim of this study was to compare the efficacy and safety of two different DCCV algorithms, Rational and Maximum Fixed Energy, in achieving sinus rhythm after DCCV. The energy of the first shock in the Rational Algorithm was based on our retrospective data.

Methods
We conducted a prospective single-blind, single-centre trial that enrolled 300 patients with AF undergoing DCCV. Patients were randomised to one of two algorithms: an initial discharge of biphasic 150 J with escalation to two times 360 J discharge if needed in a Rational Algorithm, or first discharge of 360 J and additional two 360 J discharges if needed in Maximum Fixed energy algorithm.
The primary endpoint was SR in the first minute after DCCV and any neurological complications. Secondary endpoints were skin changes immediately after DCCV and chest pain on the day after.

Results
The trial included 300 patients, divided into two arms of 150 patients each. The mean age of the patients was 68 years and 66 % were male. The mean LA diameter was 47 mm and the mean LV EF was 54.2 %. Rivaroxaban was the most frequently used NOAC (62.8 %) and the most commonly used antiarrhythmic drug was amiodarone (39 %).All patient characteristics are shown in the Table 1 below.
In the Rational Algorithm arm, 92.7 % of patients had SR one minute after DCCV compared to 94 % in the Maximum Fixed Energy Algorithm arm (p=0.643). Both arms had a similar rate of SR (91.3 %) at two hours post-DCCV. There were no neurological complications in either group. The incidence of skin redness was higher in the Maximum Fixed Energy Algorithm arm (36 %) than in the Rational Algorithm arm (19.3 %) (p=0.001), while the incidence of chest pain was similar between the two arms. We found the difference in cardioversion success rates of both algorithms after the initial shock, i.e. after 150 J vs. 360 J (109 [72.7%] vs. 125 [83.3%] patients). Univariate analysis revealed significant differences in weight (mean 104 kg in AF vs mean 91 kg in sinus rhythm, p&lt;0.001) and BMI (mean 34.1 kg/m2 in AF vs mean 30.5 kg/m2 in SR p&lt;0.001) between those who remained in AF and those who achieved SR after the initial 150 J discharge. The results are presented in Table 2 below.

Conclusion
The PROTOCOLENERGY trial suggests that both algorithms are safe and effective in achieving sinus rhythm after DCCV. Although the Maximum Fixed Energy Algorithm showed a slightly higher success rate, the difference was not statistically significant. The Rational Algorithm is associated with a lower incidence of skin redness compared to the Maximum Fixed Energy Algorithm.Table 1Table 2