Unrecognized history of transient atrial fibrillation at the time of discharge from an index stroke hospitalization is associated with increased recurrent stroke risk

Background and Purpose Preceding episodes of paroxysmal atrial fibrillation (AF) among stroke patients can be easily overlooked in routine clinical practice. We aim to determine whether an unrecognized history of paroxysmal AF is associated with an increased risk of recurrent stroke. Methods We retrospectively identified all adult patients hospitalized with a primary diagnosis of ischemic stroke who had no AF diagnosis on their discharge records, using the Taiwan National Health Insurance Research Database between January 2001 and December 2012. Patients were categorized into two groups: unrecognized AF history and no AF. Patients with unrecognized AF history were defined as having documented AF preceding the index ischemic stroke hospitalization, but not recording at the index ischemic stroke. Primary endpoint was recurrent stroke within 1 year after the index stroke. Results Among 203,489 hospitalized ischemic stroke patients without AF diagnosed at discharge, 6,731 patients (3.3%) had an unrecognized history of prior transient AF. Patients with an unrecognized AF history, comparing to those without AF, had higher adjusted risk of all recurrent stroke ([original cohort: hazard ratio (HR), 1.41; 95% confidence interval [CI], 1.30 to 1.53], [matched cohort: HR, 1.51; 95% CI, 1.37 to 1.68]) and recurrent ischemic stroke ([original cohort: HR, 1.42; 95% CI, 1.30 to 1.55], [matched cohort: HR, 1.56; 95% CI, 1.40 to 1.74]) during the 1-year follow-up period. Conclusions Unrecognized history of AF among patients discharged after an index ischemic stroke hospitalization is associated with higher recurrent stroke risk. Careful history review to uncover a paroxysmal AF history is important for ischemic stroke patients.