Abstract and Introduction
Abstract
Objectives: The aim of this study was to determine the risk of major clinical and thromboembolic events after cardioversion for atrial fibrillation in subjects treated with apixaban, an oral factor Xa inhibitor, compared with warfarin.
Background: In patients with atrial fibrillation, thromboembolic events may occur after cardioversion. This risk is lowered with vitamin K antagonists and dabigatran.
Methods: Using data from the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial, we conducted a post-hoc analysis of patients undergoing cardioversion.
Results: A total of 743 cardioversions were performed in 540 patients: 265 first cardioversions in patients assigned to apixaban and 275 in those assigned to warfarin. The mean time to the first cardioversion for patients assigned to warfarin and apixaban was 243 ± 231 days and 251 ± 248 days, respectively; 75% of the cardioversions occurred by 1 year. Baseline characteristics were similar between groups. In patients undergoing cardioversion, no stroke or systemic emboli occurred in the 30-day follow-up period. Myocardial infarction occurred in 1 patient (0.2%) receiving warfarin and 1 patient receiving apixaban (0.3%). Major bleeding occurred in 1 patient (0.2%) receiving warfarin and 1 patient receiving apixaban (0.3%). Death occurred in 2 patients (0.5%) receiving warfarin and 2 patients receiving apixaban (0.6%).
Conclusions: Major cardiovascular events after cardioversion of atrial fibrillation are rare and comparable between warfarin and apixaban. (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation [ARISTOTLE]; NCT00412984)
Introduction
Patients with atrial fibrillation (AF) who undergo cardioversion are at risk for thromboembolic events, and vitamin K antagonists appear to lower this risk. Anticoagulation with an international normalized ratio of 2.0 to 3.0 is currently recommended for 3 weeks before elective cardioversion and is to be continued for a minimum of 4 weeks after cardioversion. Dabigatran, a direct thrombin inhibitor, appears to have efficacy comparable to that of warfarin in selected patients after cardioversion.
The factor Xa inhibitor apixaban, when compared with warfarin, has been shown to reduce the risk of stroke and systemic emboli in patients with AF and risk factors for stroke in the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial. The effectiveness of apixaban for prevention of stroke in patients undergoing cardioversion is unknown. The aim of the present analysis was to compare the baseline characteristics of patients undergoing cardioversion with those not undergoing cardioversion, describe the duration of anticoagulation before cardioversion, and examine the rate of major clinical events, including stroke, systemic embolism, myocardial infarction (MI), major bleeding, and death, in these patients.