Apixaban Comparable to Warfarin After Cardioversion for Atrial Fibrillation

May 9, 2014

In a clinical trial setting, performance of the new oral anticoagulant and the long-time gold standard was similar. In the real world, where adherence can be a problem, there is a risk/benefit ratio to consider.

As patients with atrial fibrillation (AF) are increasingly considered for rhythm control strategies, the role of the novel oral anticoagulants (NOACs) in the pericardioversion period is gaining increased attention. Before the NOACS were available, the standard of care had been to document 3 to4 therapeutic INRs and/or obtain a transesophageal echocardiogram prior to cardioversion.This was usually followed by 4 additional weeks of systemic anticoagulation after atrial stunning from the electrical cardioversion.

A post-hoc analysis of the ARISTOTLE  (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) study, published in JACC in November 2013, showed that rates of stroke or systemic embolism following electrical cardioversion were similar between patients who received apixaban and those who received warfarin. There were 540 patients included in this analysis who underwent cardioversion; the group was 73% male; 26% had type 2 diabetes; and mean age was 67 years. The majority of patients (68 to71%) had persistent or permanent AF, and the mean CHADS2 score was 1.8 to 1.9. Of the 743 cardioversions performed, there were no occurrences of the primary endpoint event (stroke or systemic embolism) within 30 days of follow-up. There was one occurrence of myocardial infarction and one occurrence of major bleeding in each of the two groups as well as two occurrences of death in each arm.

This trial is subject to the usual limitations of a post-hoc analysis. However, it does demonstrate that using apixaban, an oral factor Xa inhibitor, is comparable to the uninterrupted use of warfarin for therapeutic anticoagulation during the pericardioversion period. It should be noted, however, that because of the nature of clinical trials, this patient population was more likely to be highly compliant than patients may be in the real world. Adherence to a drug that is dosed twice daily, ie, apixaban, may not be as good as adherence to a longer acting agent such as warfarin-an especially dangerous circumstance during a short period where risk for thromboembolism is high. Conversely, a subtherapeutic INR, which can occur with warfarin, during this period may expose the patient to undue risk as well. Such issues must be weighed carefully by the provider when considering the best option for pericardioversion anticoagulation.

References:

Flaker G, Lopes RD, Al-Khatib SM, et al. Efficacy and safety of apixaban in patients after cardioversion for atrial fibrillation: insights from the ARISTOTLE trial (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation). J Am Coll Cardiol. 2014;63:1082-1087. doi:10.1016/j.jacc.2013.09.062.