Stroke and Bleeding Risk in AF With CHA2DS2-VASc Score of One
- Patients with AF at intermediate stroke risk (CHA2DS2-VASc score of 1) experience lower rates of ischemic stroke with oral anticoagulation (OAC) vs. no OAC use.
- OAC use was associated with a higher rate of major bleeding but lower net clinical benefit as compared to no OAC use in this population.
- Patients with AF at intermediate stroke risk should undergo detailed shared decision-making discussion to determine if OAC therapy aligns with their values and preferences.
What is the next clinical benefit of oral anticoagulation (OAC) therapy for patients with atrial fibrillation (AF) and an intermediate risk of stroke?
The AF in Norway (AFNOR) study is a cohort study of patients in Norway with linkage between a patient registry, prescription database, and cause of death registry. All adult patients with a diagnosis of AF and a nonsex characteristic CHA2DS2-VASc score of 1 between 2011 and 2018 were included in the analysis. Patients with mitral stenosis or mechanical heart valve as well as those with prevalent use of OAC at baseline were excluded. Patients were followed until the first incidence of ischemic stroke, intracranial hemorrhage, increase in CHA2DS2-VASc score, or study period ended. Other outcomes assessed include major bleeding, defined as a hospitalization or death from intracranial bleed, gastrointestinal bleed, or fatal bleed from another site. One-year incidence rates were calculated and Cox regression models compared outcomes for patients who did and did not receive OAC therapy.
A total of 34,460 patients with AF and nonsex CHA2DS2-VASc score of 1 were identified. The incidence rate of ischemic stroke was 0.51 per 100 patient-years among OAC users and 1.05 per 100 patient-years among nonusers (adjusted hazard ratio [aHR], 0.47; 95% confidence interval [CI], 0.37-0.59). The incidence rate of intracranial hemorrhage was 0.28 per 100 patient-years among OAC users and 0.19 per 100 patient-years among nonusers (aHR, 1.23; 95% CI, 0.88-1.72). Major bleeding was more common among OAC users than nonusers (aHR, 1.37; 95% CI, 1.16-1.63). The overall combined outcome of ischemic stroke, major bleeding, and mortality was lower among OAC users than nonusers (aHR, 0.57; 95% CI, 0.51-0.63).
The authors conclude that OAC use is associated with overall favorable clinical outcomes in patients with AF at intermediate risk of stroke.
Guidelines have consistently recommended OAC therapy for patients with AF at increased risk of stroke (nonsex CHA2DS2-VASc score ≥2). However, the net clinical benefit for patients at intermediate risk of stroke (CHA2DS2-VASc score of 1) is not as clear. This population-based study finds overall benefit in favor of OAC use among this intermediate-risk population. However, this benefit does not consider the high frequency of patient-relevant bleeding events (e.g., bruising, nosebleeds) that do not lead to hospitalization or death but do create significant distress for patients and lead to increased health care utilization. While these data can help to guide patient shared decision-making around OAC initiation, they are unlikely to significantly change the strength of current guideline recommendations for patients with AF at intermediate risk of stroke.
Keywords: Anticoagulants, Atrial Fibrillation, Stroke
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