The Risk of Stroke after Acute Myocardial Infarction in Patients with and without Atrial fibrillation: A Nationwide Cohort Study in Taiwan

Background: Both acute myocardial infarction (AMI) and atrial fibrillation (AF) are risks for stroke. The risk of stroke after AMI may be different in patients with or without AF. The aim of this study was to evaluate the impact of AF on stroke in patients after first AMI. Methods This is a retrospective nationwide cohort study. A total of 170,472 patients who had the primary diagnosis of first AMI between 2000 and 2012 were enrolled. Among them, 8,530 patients with AF were identified. Propensity score matching technique was used to match 8,530 patients without AF with similar ages and genders. All patients were followed until stroke or 31 December 2012, whichever occurred first. Kaplan–Meier cumulative survival curves were constructed to compare stroke between AMI patients with and without AF. Results Overall, 12-year stroke rate was higher in patients with AF than without AF (log rank P-value < 0.001), including in different genders, ages, or intervention subgroups. In patients with AF, those with preexisted AF had higher stroke rates in male gender, age below 65 years, and with intervention subgroups than those with new-onset AF. In Cox proportional-hazard regression analysis, AF was an independent risk factor for stroke after first AMI (hazard ratio, 1.67; 95% confidence interval, 1.5–1.87). Conclusions AF significantly increased stroke risks after first AMI. In patients with AF, those with preexisting AF have higher stroke risks in male genders, ages below 65 years, and with interventions than those with new-onset AF.