By Matthew E. Fink, MD

Professor and Chairman, Department of Neurology, Weill Cornell Medical College; Neurologist-in-Chief, New York Presbyterian Hospital

Dr. Fink reports he is a consultant for Procter & Gamble and Pfizer.

SOURCE: Kamel H, et al. Electrocardiographic left atrial abnormality and stroke subtype in the Atherosclerosis Risk in Communities Study. Ann Neurol 2015;78:670-678.

Atrial fibrillation is a known risk factor for ischemic stroke, with a three- to five-fold heightened risk. However, it is now being recognized that left atrial abnormalities that do not necessarily result in atrial fibrillation, such as endothelial dysfunction, fibrosis, and chamber dilatation, may also increase the risk of stroke. All of these abnormalities may increase the risk of thrombus formation in the left atrium and subsequent cerebral embolism. In this study, the investigators analyzed the presence of left atrial abnormality as defined on electrocardiogram by the P-wave terminal force in lead V1 > 4000 µV per meter-squared. The cohort consisted of 14,542 participants aged 45 to 64 years, prospectively enrolled in a population-based study, and free of clinically apparent atrial fibrillation. Outcomes were ischemic stroke, divided into non-lacunar and lacunar stroke. During a median follow-up period of 22 years, 904 participants (6.2%) experienced a definite or probable ischemic stroke. The incidence of stroke was higher in those with a baseline left atrial abnormality as defined above, 6.3 per 1000 patient-years, compared to 2.9 per 1000 patient-years in those without atrial abnormalities. In a regression model, the presence of a left atrial abnormality was associated with a hazard ratio of 1.33 (statistically significant). This association was limited to non-lacunar stroke (hazard ratio = 1.49) and would be consistent with cardiogenic embolism as a cause for ischemic stroke. Left atrial abnormalities should be investigated and searched for in patients with ischemic stroke consistent with cardiogenic embolism, even in the absence of atrial fibrillation.