P4812Comparison of ischemic stroke risk in atrial fibrillation patients with or without myocardial infarction: a propensity score matched study

Background: Stroke risk in atrial fibrillation (AF) is commonly associated with myocardial infarction (MI). The risk of stroke in AF correlates well with the CHA2DS2-VASc score but still have some heterogeneous aspect. Purpose: We investigated whether the presence of prior MI increases stroke risk in AF patients with similar risk degree. Methods: This study included consecutive 5,585 patients who were diagnosed with AF in a tertiary hospital from 2007 to 2017. Patients were divided into two groups according to presence of MI (group 1, AF patients with MI, n=308; group 2: AF patients without MI, n=5,277). Propensity score matching to adjust relevant risk factors including age, sex, and CHA2DS2-VASc score was performed to account for the difference between the two groups (Standardized Difference of all variables<0.005). Results: In the initial study population (mean 66±13 years old, 41.1% female, mean 77±42 follow-up months), after 1:5 propensity matching for age, sex and CHA2DS2-VASc score, the mean CHA2DS2-VASc score for each group was not significantly different (2.4±1.5 vs. 2.4±1.5, p=0.446). The proportion of heart failure (p=0.762), hypertension (p=0.077) and vascular disease (p=0.367) were similar between the two groups. However, group 1 had higher proportion of diabetes mellitus than group 2 (27.3% vs. 17.8%, p=0.002). In the matched groups, group 1 showed a significant increased incidence of ischemic stroke than group 2 (41.6% vs. 23.8%, p=0.001). The proportion of oral anticoagulation (p=0.162) and antiplatelet agent treatment (p=0.453) showed no significant difference between the groups. Cox-regression using a relevant risk factors revealed that MI (HR 2.39, 95% CI 1.11–5.15, p=0.026) was significantly associated with ischemic stroke.