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Amiodarone use increased stroke, systemic embolism risk in patients with AF
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Patients with atrial fibrillation who received amiodarone at baseline in the ARISTOTLE trial, along with apixaban or warfarin, had an increased risk for developing stroke or systemic embolism and had a shorter time in the therapeutic range compared with patients who did not receive amiodarone, according to a new analysis.
Researchers evaluated baseline characteristics of 17,907 participants of the ARISTOTLE trial who received amiodarone (n=2,051) or did not receive amiodarone (n=15,856) at randomization. In the trial, patients were randomly assigned apixaban (Eliquis; Bristol-Myers Squibb, Pfizer) or warfarin. The primary efficacy outcome was stroke, the primary safety outcome was major bleeding, and secondary outcomes included MI and death. Mean follow-up was 21 months. The overall results of the ARISTOTLE trial were reported previously.
According to results of the new analysis, patients who received amiodarone and warfarin had a shorter time in the therapeutic range compared with patients who did not receive amiodarone (56.5% vs. 63%; P<.0001). Stroke or systemic embolism was more frequent in patients who received amiodarone (1.58%/year vs. 1.19%/year; adjusted HR=1.47; 95% CI, 1.03-2.1). The researchers observed numerically higher rates of all-cause, CV-related and non–CV-related mortality among patients who received amiodarone, but the difference between the amiodarone treatment groups was not significant.
When the researchers compared apixaban vs. warfarin treatment, amiodarone recipients who received apixaban were less likely to experience stroke or systemic embolism (HR=0.68; 95% CI, 0.4-1.15), mortality (HR=0.74; 95% CI, 0.55-0.98) or major bleeding (HR=0.61; 95% CI, 0.39-0.96). Those assigned apixaban who did not receive amiodarone also were at reduced risk for stroke or systemic embolism (HR=0.82; 95% CI, 0.68-1), mortality (HR=0.93; 95% CI, 0.83-1.05) and major bleeding (HR=0.72; 95% CI, 0.62-0.84) compared with warfarin.
“Amiodarone use was associated with a significantly higher risk of stroke and systemic embolism. The relative effects of apixaban vs. warfarin on stroke and systemic embolism, mortality and major bleeding were consistent in patients who received and patients who did not receive amiodarone,” the researchers concluded.
Jonathan L. Halperin
In a related editorial, Juan F. Viles-Gonzalez, MD, from the University of Miami Miller School of Medicine, and Jonathan L. Halperin, MD, from the Icahn School of Medicine at Mount Sinai, wrote that this analysis has some limitations: Patients with permanent and persistent AF were not distinguished from one another; amiodarone treatment duration was not specified; and the researchers did not adjust for left ventricular ejection fraction or hepatic or renal disease. However, they recognized the report as the first to assess the safety and efficacy of amiodarone among apixaban recipients.
“Similar analyses of outcomes among patients with AF in trials of other target-specific anticoagulants could enhance our understanding of the safety and efficacy of amiodarone therapy in particular, and antiarrhythmic therapy in general, without the encumbrances of warfarin,” Viles-Gonzalez and Halperin wrote.
For more information:
Flaker G. J Am Coll Cardiol. 2014;64:1541-1550.
Viles-Gonzalez JF. J Am Coll Cardiol. 2014;64:1551-1553.
Disclosure: See the full study and editorial for a list of relevant financial disclosures.