P2904Age threshold for ischemic stroke risk in atrial fibrillation: cohort data covering the entire Korean population

Background: Although older age is the most important risk factor for stroke in atrial fibrillation (AF), the appropriate age threshold (eg. CHA2DS2-VASc score, 1 point for age 65-74, 2 points for age 75) for increased risk is controversial, as actual age thresholds may differ between countries and ethnic groups. We investigated the age threshold for ischemic stroke risk among Asian AF patients. Methods: Using National Health Insurance Service database including 426,650 oral anticoagulant-nave non-valvular AF patients from 2005-2015, with 2 or less nongender-related (NGR) CHA2DS2-VASc risk scores (CHA2DS2-VASc score 0 to 2 in males, 1 to 3 in females), we assessed the risk of ischemic stroke in AF patients according to the age. Results: Patients who fulfill the age risk criterion (age 65-74) without other risk factors showed a significantly higher risk of stroke (4.76 per 100 Person-Years [100PY], adjusted Hazard Ratio [aHR] 2.25, 95% confidence interval [CI] 2.17-2.36) compared to patients with 1 risk score other than age (1.87/100PY). Patients aged 55-59 with no risk factors showed similar risk of stroke (1.94/100PY, aHR 1.02, 95% CI 0.94-1.10) than patients with 1 risk score (2.06/100PY). Patients aged 65-69 and no other risk factors had similar stroke risk (4.08/100PY, aHR 0.94, 95% CI, 0.88-1.00) than patients with 2 NGR risk scores (4.42/100PY).