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Apixaban for Stroke Prevention in Patients With Subclinical Atrial Fibrillation
TAKE-HOME MESSAGE
- Recent studies have shown that implantable cardiac monitors improve the detection of subclinical atrial fibrillation (AF), but the clinical benefit of anticoagulation is not clear. This randomized clinical trial investigated whether therapeutic anticoagulation with apixaban in patients with subclinical AF detected by a pacemaker, a defibrillator, or an implantable cardiac monitor improved clinical outcomes. The authors included patients who had at least one episode lasting 6 minutes or longer but no episodes lasting longer than 24 hours. Most patients (>70%) had AF detected by a pacemaker. Fewer than 10% of the patients had a history of stroke at baseline. The majority of the patients (>60%) had one to five episodes in 6 months, with their longest episode lasting 6 minutes to 6 hours. The mean follow-up duration was 3.5 years. The risk of stroke or systemic embolism was significantly lower with apixaban than with aspirin (HR, 0.63; P = .007). The risk of major bleeding events was higher in the apixaban group (1.71% vs 0.94%; P = .001), and this difference was mainly driven by gastrointestinal system hemorrhages.
- Therapeutic anticoagulation with apixaban in patients with subclinical AF protects against stroke or systemic embolism, with an increased risk of major gastrointestinal hemorrhage.
abstract
This abstract is available on the publisher's site.
Access this abstract nowBACKGROUND
Subclinical atrial fibrillation is short-lasting and asymptomatic and can usually be detected only 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, treatment with oral anticoagulation is of uncertain benefit.
METHODS
We conducted a trial involving patients with subclinical atrial fibrillation lasting 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. The trial medication was discontinued and anticoagulation started 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 the patients who had undergone randomization); the primary safety outcome, major bleeding, was assessed in the on-treatment population (all the patients who had undergone randomization and received at least one dose of the assigned trial drug, with follow-up censored 5 days after permanent discontinuation of trial medication for any reason).
RESULTS
We included 4012 patients with a mean (±SD) age of 76.8±7.6 years and a mean CHA2DS2-VASc score of 3.9±1.1 (scores range from 0 to 9, with higher scores indicating 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 on-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 bleeding 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 a higher risk of major bleeding. (Funded by the Canadian Institutes of Health Research and others; ARTESIA ClinicalTrials.gov number, NCT01938248.).
Additional Info
Disclosure statements are available on the authors' profiles:
Apixaban for Stroke Prevention in Subclinical Atrial Fibrillation
N. Engl. J. Med 2023 Nov 12;[EPub Ahead of Print], JS Healey, RD Lopes, CB Granger, M Alings, L Rivard, WF McIntyre, D Atar, DH Birnie, G Boriani, AJ Camm, D Conen, JW Erath, MR Gold, SH Hohnloser, J Ip, J Kautzner, V Kutyifa, C Linde, P Mabo, G Mairesse, J Benezet Mazuecos, J Cosedis Nielsen, F Philippon, M Proietti, C Sticherling, JA Wong, DJ Wright, IG Zarraga, SB Coutts, A Kaplan, M Pombo, F Ayala-Paredes, L Xu, K Simek, S Nevills, R Mian, SJ ConnollyFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Every fifth implanted pacemaker, defibrillator, cardiac resynchronization device, or loop recorder detects short episodes of atrial fibrillation (AF). These show the features of AF, but the events are rare and short. Whether these episodes of device-detected AF require anticoagulation was tested in two randomized double-blind studies comparing the outcomes between anticoagulation therapy with an NOAC (apixaban or edoxaban) and aspirin (ARTESiA1) or among an NOAC, aspirin, and no antiplatelet therapy based on accepted indications (NOAH-AFNET 62). Both studies show consistent results.3 There are two pieces of good news for patients with device-detected AF in the results:
Like many robust studies, the results call for more evidence; the low stroke rate and the weak but unambiguous effect of anticoagulation call for research into better methods to estimate stroke risk in patients with rare and short episodes of AF. Such research may integrate arrhythmia burden, genetic information, and quantitative proxies of atrial, ventricular, and vascular function (eg, biomolecules).
Until such research reports become available, clinical advice on the management of patients with device-detected AF will continue to rely on conversations explaining the benefits and risks of anticoagulation, with shared decision–making tailored to the values and needs of each patient.
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