Background: Atrial fibrillation (AF) is a well-known risk factor for ischemic stroke; however, it is unclear if atrial fibrillation burden in patients with PAF is correlated with increased stroke risk.
Study design: Retrospective cohort chart review study during October 2011–October 2016.
Setting: Outpatients in two Kaiser Permanente California health systems.
Synopsis: Among 1,965 adult patients with PAF not on anticoagulation therapy, PAF burden was defined as the percentage time spent in AF during 14-day ECG monitoring. Outcomes included hospitalization for ischemic stroke or arterial thromboembolism while not taking anticoagulants.
Patients in the highest tertile of PAF burden (less than 11%) had 215% higher risk of thromboembolic events, compared with those with lower PAF burden (less than 11%), yielding a hazard ratio of 3.15 (95% confidence interval, 1.51-6.61), even after adjustment.
This study was limited by short ECG monitoring period (14 days), low total number of events (29 total events, 17 in the highest tertile), and no minimum follow-up time. Further, with all patients insured in a single health care system, and excluded on disenrollment from the health plan, selection bias could have affected the results.
Bottom line: In patients with PAF, a larger AF burden (greater than 11%) is associated with increased risk of ischemic stroke. Assessment of AF burden may help determine the need for anticoagulation for stroke prevention.
Citation: Go AS et al. Association of burden of atrial fibrillation with risk of ischemic stroke in adults with paroxysmal atrial fibrillation: the KP-RHYTHM study..
Dr. Hanna is an assistant professor in the division of hospital medicine, University of Colorado, Denver.