Background
Subclinical atrial fibrillation is short-lived and asymptomatic and can usually only be detected by long-term continuous monitoring with pacemakers or defibrillators. Subclinical atrial fibrillation is associated with an increased risk of stroke by a factor of 2.5; however, the benefit of oral anticoagulation treatment is uncertain.
Methods
We conducted a trial with patients with subclinical atrial fibrillation that lasted from 6 minutes to 24 hours. Patients were randomly assigned in a double-blind, double-dummy design to receive apixaban at a dose of 5 mg twice daily (2.5 mg twice daily when indicated) or aspirin at a dose of 81 mg daily.
Trial medication was discontinued and anticoagulation initiated if subclinical atrial fibrillation lasting more than 24 hours or clinical atrial fibrillation developed.
The primary efficacy outcome, stroke or systemic embolism, was assessed in the intention-to-treat population (all patients who had been randomized); The primary safety outcome, major bleeding, was assessed in the treatment population (all patients who had undergone randomization and received at least one dose of assigned trial drug, with follow-up censored 5 days after permanent discontinuation). of trial medication for any reason).
Results
4,012 patients were included with a mean age (± SD) of 76.8 ± 7.6 years and a mean CHA 2 DS 2 -VASc score of 3.9 ± 1.1 (scores range between 0 and 9, and higher scores indicate a higher risk of stroke); 36.1% of the patients were women.
After a mean follow-up of 3.5 ± 1.8 years, stroke or systemic embolism occurred in 55 patients in the apixaban group (0.78% per patient-year) and in 86 patients in the aspirin group (1, 24% per patient-year) (hazard ratio, 0.63; 95% confidence interval [CI], 0.45 to 0.88; P = 0.007).
In the treatment population, the rate of major bleeding was 1.71% per patient-year in the apixaban group and 0.94% per patient-year in the aspirin group (hazard ratio, 1.80; 95% CI, 1.26 to 2.57; P = 0.001).
Fatal hemorrhage occurred in 5 patients in the apixaban group and 8 patients in the aspirin group.
Conclusions Among patients with subclinical atrial fibrillation, apixaban resulted in a lower risk of stroke or systemic embolism than aspirin, but an increased risk of major bleeding. |
(Funded by the Canadian Institutes of Health Research and others; ARTESIA ClinicalTrials.gov number, NCT01938248)
