Characteristics and outcomes of ischemic stroke in patients with known atrial fibrillation or atrial fibrillation diagnosed after stroke

Background: It is unclear whether ischemic stroke patients with known atrial fibrillation (KAF) had different outcomes than those with atrial fibrillation diagnosed after stroke (AFDAS). We aimed to explore the characteristics and outcomes in ischemic stroke patients with KAF or AFDAS. Methods: Consecutive patients hospitalized between 2000 and 2012 for first-ever stroke along with atrial fibrillation, either diagnosed before or during the stroke hospitalization, were identified from a nationwide claims database in Taiwan. The outcome of interest was a composite outcome of ischemic stroke, intracranial hemorrhage, or death within one year. Univariable and multivariable Cox regression analyses were used to determine the effect of KAF versus AFDAS on the composite outcome. Results: We identified 1161 patients, of whom 481 (41.4%) had KAF and 680 (58.6%) had AFDAS. Age, sex, and stroke severity were similar between groups. However, patients with KAF had a higher prevalence of underlying heart diseases than those with AFDAS (67.2% versus 39.0%, p < 0.001). In univariable analysis, patients with KAF had a higher risk of the composite outcome than those with AFDAS (hazard ratio [HR]: 1.42, 95% confidence interval [CI]: 1.13–1.79, p = 0.003). In multivariable analysis, KAF was no longer independently associated with the composite outcome. Conclusions: As compared to ischemic stroke patients with AFDAS, those with KAF had a higher prevalence of underlying heart diseases. Whether AF was known before or diagnosed after stroke was not an independent predictor of the composite outcome.