A dual direct-current cardioversion technique achieved a higher success rate than the standard single shock approach for restoring normal heart rhythm in patients with obesity and atrial fibrillation, according to a multicenter randomized clinical trial published in JAMA Cardiology. The study reported a 98% cardioversion success rate with dual shocks compared to 86% with single shocks.

The trial enrolled 210 patients with a body mass index (BMI) of ≥ 35 who were undergoing elective cardioversion for atrial fibrillation (AFib) at 3 centers in Louisiana. Of these, 200 patients (median age 67.6 years, 63.5% male, mean BMI 41.2) completed the study. Participants were randomized to receive either a single 200-joule shock using 1 set of pads or 2 simultaneous 200-joule shocks using 2 sets of pads in a crisscrossing configuration.

After the first attempt, sinus rhythm was restored in 97 out of 99 patients (98%) in the dual shock group compared to 87 out of 101 patients (86%) in the single shock group, a statistically significant difference (P = .002). Researchers noted the odds ratio for success with dual shocks was 6.7 (95% CI, 3.3-13.6; P = .01). All 14 patients who failed to convert with an initial single shock were subsequently successfully cardioverted using the dual shock technique on the second or third attempt. There were no major adverse events and no difference in reported chest discomfort between the 2 groups.

According to the researchers, the dual shock approach may overcome some of the obstacles to successful cardioversion in patients with obesity, such as higher transthoracic impedance, larger chest size, and enlarged atria. By delivering more total energy from different vectors, the dual shock technique could achieve the critical myocardial current density required to terminate AFib.

AFib is the most common heart rhythm disorder, and its prevalence is increasing alongside the obesity epidemic, informed researchers. Electrical cardioversion is often required to restore normal sinus rhythm, and obesity is a well-documented predictor of cardioversion failure according to multiple studies. The researchers suggest that further research is needed to determine if the dual shock approach improves long-term maintenance of sinus rhythm or reduces complications.

The study was single-blinded and focused on the immediate restoration of sinus rhythm, not long-term outcomes. Despite these limitations, the researchers noted findings indicate that dual direct-current cardioversion (DCCV) is a promising approach for managing AFib in patients with obesity.

Conflict of interest disclosures can be found in the study.