Prevalence of stroke and the need for thromboprophylaxis in young patients with atrial fibrillation: a cohort study.

Atrial fibrillation is the most common cardiac arrhythmia, and age is a well-established independent risk factor for stroke in these patients. Whereas high-risk patients clearly benefit from anticoagulation to prevent stroke, less is known about how to treat low-risk patients. Despite the recent guidelines and studies demonstrating no benefit and excess bleeding risk with aspirin, many low-risk patients still receive this medication. Our objective was to determine the stroke rate in young patients with atrial fibrillation, a group of previously unstudied and predominantly low-risk patients. We hypothesized that the event rate would be so low as to preclude benefit from antithrombotic medications. A retrospective chart review identified patients with atrial fibrillation between the age of 18 and 35. Exclusion criteria included no ECG documentation of atrial fibrillation, anticoagulation, except around the time of cardioversion, and surgical valve disease. The primary outcome was stroke during the period of observation. The final cohort included 99 patients, mean age 27.6 years, followed for a mean of 4.3 years. Mean CHADS2 and CHA2DS2-VASc scores were 0.26 and 0.4, respectively. A total of 42.4% were taking aspirin for over 50% of the time. There was one event identified, a transient ischemic attack in a man not on aspirin with CHADS2 and CHADS2-VASc scores of 1, resulting in event rates of 0.234 per 100 patient-years overall or 0.392 among those not on aspirin. Patients with nonvalvular atrial fibrillation under age 35 have an exceedingly low stroke risk. We assert that aspirin may be unnecessary for most patients in this population, especially those with a CHA2DS2-VASc score of 0.