Oral anticoagulation in atrial fibrillation patients at intermediate risk of stroke: a nationwide registry-based cohort (Atrial Fibrillation in Norway – AFNOR). (14th October 2021)

• Record Type: Journal Article
• Authors: Anjum, M; Ariansen, I; Hjellvik, V; Kjerpeseth, L.J; Selmer, R; Skovlund, E; Egeland, G.M; Christophersen, I.E; Myrstad, M; Tveit, A; Berge, T
• Is Part Of: European heart journal. Volume 42(2021)Supplement 1
• Publication Date: 2021-10-14
• Subjects: Stroke in Atrial Fibrillation; Cardiology -- Periodicals; Heart -- Diseases -- Periodicals; 616.12005
• DOI: 10.1093/eurheartj/ehab724.0473
• Languages: English
• ISSNs: 0195-668X

Abstract

Abstract: Background: The effect of oral anticoagulants (OAC) on prevention of stroke must be carefully balanced against the potential risk of bleeding in patients with atrial fibrillation (AF). The net benefit of OAC in AF patients at intermediate risk of stroke remains unclear. Aim: We aimed to determine whether the rates of ischemic and haemorrhagic stroke differ between users and non-users of OAC in a nationwide cohort of AF patients at intermediate risk of stroke. Method: We investigated the association between initiation of OAC treatment and rates of ischemic and haemorrhagic stroke in a cohort of Norwegian patients with non-valvular AF aged ≥18 years with one non-sex CHA2DS2-VASc risk factor registered from 2011 to 2018, linking data from the Norwegian Population Registry, Patient Registry, Prescription Database and Cause of Death Registry. Individuals using OAC at baseline were excluded. Each individual had at least a three years look-back period for identification of their first non-sex CHA2DS2-VASc risk factor, after which they entered the study cohort and were followed until occurrence of stroke, death, emigration, higher CHA2DS2-VASc score or end of follow-up on December 31, 2018. Individuals were defined as exposed to OAC from the first redeemed prescription of OAC with a reimbursement code for AF and throughout follow-up. Rates of ischemic and haemorrhagic stroke were calculated as the number of stroke cases per 100 person-years, with 95% confidence intervals (CI). Results: During 2011–2018, a total of 61, 631 individuals with AF and intermediate risk of stroke were included (mean age 63, 8±7, 6 years (SD); 37% women), of whom 75% initiated OAC treatment. In total, 1709 ischemic strokes (405 cases in OAC users and 1304 in non-users) were registered during 214, 738 person-years, and 378 haemorrhagic strokes (251 cases in OAC users and 127 in non-users) during 213, 487 person-years. The rate of ischemic stroke was 0.39 (95% CI, 0.35–0.43) and 1.19 (95% CI, 1.12–1.25) per 100 person-years in OAC users and non-users, respectively. The haemorrhagic stroke rate was 0.24 (95% CI, 0.21–0-27) and 0.12 (95% CI, 0.10–0.14) per 100 person-years in OAC users and non-users, respectively. Both ischemic and haemorrhagic stroke rates were highest among those over 65 years of age (Figure 1). Conclusion: In a nationwide cohort of Norwegian AF patients at intermediate risk of stroke, three out of four initiated treatment with OAC. Use of OAC was associated with a considerably lower rate of ischemic stroke compared to non-OAC use. Although haemorrhagic stroke rates were increased in the OAC-users vs. non-users, the hemorrhagic stroke rates were generally low. Funding Acknowledgement: Type of funding sources: Public hospital(s). Main funding source(s): Vestre Viken Health Trust