Apixaban is better than aspirin in preventing stroke in patients with atrial fibrillation.

A study showed that apixaban is more effective than aspirin for preventing stroke in patients with atrial fibrillation.

The results of a clinical trial on apixaban for the prevention of stroke in patients with asymptomatic atrial fibrillation, conducted by researchers including Jeff S. Healy of the Population Health Research Center at McMaster University in Canada, were published in the international journal NEJM on the 12th (DOI: 10.1056/NEJMoa2310234).

Atrial fibrillation is a condition in which the atrium contracts irregularly. Usually, if blood does not flow smoothly in the atria and blood clots form, the risk of stroke increases, so antithrombotic drugs to prevent blood clots are administered to lower the risk.

Previous studies have shown that administering oral antithrombotic drugs to patients diagnosed with atrial fibrillation reduces the risk of stroke by up to 2/3, but increases the risk of bleeding.

Asymptomatic atrial fibrillation has a short duration and no symptoms, and can generally be detected only through long-term continuous monitoring using a pacemaker or defibrillator.

Asymptomatic atrial fibrillation is associated with a 2.5-fold increased risk of stroke, but there is still no clear answer as to which component of oral anticoagulant treatment is optimal.

The researchers divided 4,012 patients with asymptomatic atrial fibrillation lasting from 6 minutes to 24 hours into two groups, with one group receiving 5 mg of apixaban twice a day or 81 mg of aspirin twice a day.

The primary study endpoint was the occurrence of stroke or systemic embolism, and the patients were followed up for an average of 3.5 years.

As a result of the analysis, the incidence of stroke or systemic embolism in the apixaban treatment group was 55, and the incidence of stroke or systemic embolism in the aspirin group was 86 (HR 0.63), showing that the risk was reduced by approximately 37% with apixaban.

In particular, fatal or disabling strokes were reduced by 51%, but the risk of major bleeding was 74% higher in the apixaban group compared to the aspirin group (1.69% vs. 0.96%).

The researchers said, “Currently, there are no consistent guidelines on how to treat asymptomatic atrial fibrillation with implanted heart devices.” They added, “Related clinical trials have shown that apixaban has a higher risk of stroke or systemic embolism than aspirin in patients with asymptomatic atrial fibrillation.” “It was lowered, but the risk of major bleeding was higher,” he concluded.