Prevalence and risk factors of silent ischemic brain lesion in patients with atrial fibrillation

Abstract

Introduction: The various prevalence of silent ischemic stroke (SIBL) in atrial fibrillation (AF) has been reported. Stroke history is point of two in CHADS2 scoring system, thus probably unknown portion of patients with CHADS2 score of zero or one has been undertreated in terms of stroke prevention. We investigated the risk factors for SIBL using magnetic resonance imaging (MRI) and its impacts on the clinical outcome in AF population.

Methods: Total 1200 individuals (400 with AF and 800 with sinus rhythm), who have done brain MRI for the purpose of routine health-check-up, were analyzed. Clinical outcomes including symptomatic stroke, dementia and cognitive disorder were also evaluated in AF patients (follow-up duration: 66.7±35.9, range 10-162 months).

Results: SIBL was observed in 113 (28.3%) of AF patients, which is higher than sinus rhythm individuals (p<0.001, OR 5.549). Independent risk factors for SIBL in AF patients were age (OR=1.049), hypertension (OR=2.086), dyslipidemia (OR=2.073), and valvular AF (OR=3.157). Symptomatic stroke incidence during the follow-up was higher in AF patients with SIBL (5.6%/y) than those without SIBL (2.7%/y). Among 374 non-valvular AF patients, the thromboembolic risk of 61 (23.6%) patients with SIBL among 259 patients with manifest CHADS2 score under 1, were underestimated and only 16 (26.2%) patients were taking warfarin.

Conclusions: SIBL is observed in more than a quarter of AF population, especially in patients with valvular AF, old age, dyslipidemia, and hypertension. Screening brain MRI could be considered for risk stratification for AF patients with these risk factors to avoid underestimation of thromboembolic risk.