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Clinical Articles, News & Views

Apixaban as good as warfarin after cardioversion

Major cardiovascular events after cardioversion of atrial fibrillation (AF) are rare and comparable between warfarin and apixaban, according to a study1 published recently in the Journal of the American College of Cardiology.

To determine the risk of major clinical and thromboembolic events after cardioversion for AF in subjects treated with apixaban, an oral factor Xa inhibitor compared with warfarin.

In patients with AF, thromboembolic events may occur after cardioversion. This risk is lowered with vitamin K antagonists and dabigatran. Using data from ARISTOTLE (Apixaban for Reduction In Stroke and Other Thromboembolic Events in Atrial Fibrillation), the authors conducted a post-hoc analysis of patients undergoing cardioversion.

A total of 743 cardioversions in 540 patients were performed: 265 first cardioversions in patients assigned to apixaban and 275 in those receiving warfarin. The mean time to the first cardioversion for patients assigned to warfarin and apixaban was 243 ± 231 and 251 ± 248 days respectively; 75% of the cardioversions occurred by one 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 (MI) occurred in one patient (0.2%) receiving warfarin and one receiving apixaban (0.3%). Major bleeding occurred in one patient (0.2%) receiving warfarin and one receiving apixaban (0.3%). Death occurred in two patients (0.5%) receiving warfarin and two patients receiving apixaban (0.6%).

In an accompanying editorial, Dr Matthew Reynolds (Lahey Hospital & Medical Center, Boston, USA) said: “The study from Flaker et al. has a few minor limitations that do not significantly detract from the study’s main findings. First, given the low expected event rate following cardioversion, and the limited number of observed procedures, this analysis did not have sufficient statistical power to find a small difference in outcomes between the warfarin and apixaban groups, nor was any strict definition of non-inferiority proposed or met.”

“Nonetheless, the reported experience was large enough to rule out any large difference in the safety of cardioversion with apixaban as four compared with warfarin and the results are certainly reassuring. Second, the data collection forms were either designed or interpreted in such a way that the authors could not be certain that all of the cardioversions recorded were actually done for AF. This probably has no bearing on the primary end point, but the reported secondary end points may need to be interpreted with caution as a result,” he added.

“What we have learned from the current study, as well as those from the RE-LY and ROCKET-AF trials is that cardioversions performed in the carefully controlled setting of a phase III randomized controlled clinical trial is associated with a low risk of embolic complications that probably does not differ whether the patient is treated with warfarin or any of the new oral anticoagulants (NOACs). For patients who have been treated with a NOAC for months and seem reliable with respect to adherence, there would appear to be no justification for switching them to warfarin if a cardioversion is planned,” Dr Reynolds concluded.


1. Flaker G, Lopes RD, Al-Khatib SM, et al. Efficacy and safety of apixaban in patients following cardioversion for atrial fibrillation: insights from the ARISTOTLE trial. J Am Coll Cardiol 2013.

2. Reynolds MR. Cardioversion with novel oral anticoagulants: reconfirming a 50-year old standard. J Am Coll Cardiol 2013.

Published on: November 20, 2013

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  • ArrhythmiaAlliance
  • Stars
  • Anticoagulation Europe
  • Atrial Fibrillation Association

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