Intravenous vernakalant for acute termination of recent onset atrial fibrillation in the emergency department

Atrial fibrillation (AF) significantly increases cardiovascular complications, particularly during its initial year. Early conversion to sinus rhythm is essential, and while electrical cardioversion is effective, it poses sedation-related risks. Vernakalant, an atrial-selective antiarrhythmic drug, has shown promise for rapid AF termination.

This study aimed to evaluate the predictors for successful cardioversion using Vernakalant in a large cohort of patients treated in the emergency department (ED).

We conducted and observational retrospective cohort study which included consecutive patients presenting with recent onset AF to our ED between 2016 and 2024, who received intravenous vernakalant. Vernakalant was administered to eligible patients following two protocols: from 2016-2022, a fixed dose of 300 mg (initial dose) and 200 mg (second dose) were infused over 10 minutes each; from 2022 onward, a weight-adjusted protocol (3 mg/kg for the first dose, up to 300 mg, and 2 mg/kg for the second dose) was used. The study primary efficacy outcome was conversion to sinus rhythm after vernakalant. The primary safety outcome was the occurrence of a severe adverse event (SAE) after vernakalant treatment.

Among 328 patients treated with Vernakalant, 214 (65%) recieved the simplified dose regimen and 114 (35%) recieved the weight-adjusted regimen. 268 (82%) achieved successful conversion to sinus rhythm. The efficacy was similar between a fixed-dose protocol (300 mg) and a weight-adjusted regimen, though the fixed-dose group had a higher initial conversion rate (70% vs. 56%, p=0.015). Multivariate analysis identified higher first-dose Vernakalant (adjusted OR 1.87 per additional mg/kg, p<0.01) as a significant predictor of successful cardioversion. Adverse events occurred in 10% of patients, with 0.6% experiencing SAEs. One mortality, in the weight-adjusted regimen was linked to undiagnosed dilated cardiomyopathy, highlighting the need for careful patient assessment.

In this large study, our findings support the use of Vernakalant for rapid cardioversion in the emergency setting, demonstrating high efficacy and manageable safety profiles. Increased dosing appears to correlate with improved success rates, suggesting clinical utility despite current regulatory limitations. Future studies should address long-term outcomes and pharmacodynamics to optimize treatment protocols for AF in emergency setting.