Stroke and Systemic Thromboembolism according to CHA₂DS₂-VASc Score in Contemporary Korean Patients with Atrial Fibrillation

Purpose: The incidence of stroke and/or systemic thromboembolism (SSE) has not been properly evaluated in well-anticoagulated atrial fibrillation (AF) patients. This study investigated the incidence of SSE according to CHA₂DS₂-VASc score in contemporary well-anticoagulated Korean AF patients. Materials and Methods: From the prospective multicenter COmparison study of Drugs for symptom control and complication prEvention of Atrial Fibrillation (CODE-AF) registry, we identified 9503 patients with non-valvular AF (mean age, 68±8 years; female 35.5%) enrolled between June 2016 and May 2020 with eligible follow-up visits. Stroke incidence in the CODE-AF registry was compared with that in an oral anticoagulant (OAC)-naïve AF cohort from the Korean National Health Insurance database. Results: The usage rates of OACs and antiplatelet agents were 73.5% (non-vitamin K OACs, 56.4%; warfarin, 17.1%) and 23.8%, respectively. During a mean follow-up period of 26.3±9.6 months, 163 (0.78 per 100 person-years) patients had SSE. The incidence rate (per 100 person-years) of SSE was 0.77 in the total population, 0.26 in low-risk patients [CHA₂DS₂-VASc score 0 (male) or 1 (female)], and 0.88 in high-risk patients (CHA₂DS₂-VASc score ≥2). Contemporary AF patients had a stroke rate that was about one-fifth the stroke rate reported in a Korean OAC-naïve AF cohort. In this cohort, most risk factors for CHA₂DS₂-VASc score showed significant associations with SSE. Female sex was not associated with an increased risk of stroke/SSE in well-anticoagulated AF patients. Conclusion: Contemporary AF patients have a stroke rate about one-fifth that in OAC-naïve AF patients and exhibit different stroke risk factors. Study Registration: ClinicalTrials.gov (NCT02786095).