Left atrial (LA) enlargement is a predictor of cardiovascular outcomes such as atrial fibrillation (AF), stroke, and death. The aim of this study was to explore the relationship between LA size and cognitive function in elderly patients without any signs of clinical dementia, AF or previous stroke. We assessed the cognitive status and LA volume (LAV) of 108 consecutive patients (27 males; mean age, 74.8 +/- 6.9 years) with sinus rhythm. Cognitive status was assessed by the Mini Mental State Examination (MMSE). Patients with a MMSE score of <= 25 were considered to have cognitive impairment. LAV was measured with two-dimensional echocardiography. LAV index (LAVI) was obtained by indexing LAV to body surface area. Thirty-five patients (32.4%) had cognitive impairment. The patients with cognitive impairment had significantly larger left atria than the patients with normal cognitive function. Receiver operating characteristic analysis revealed a cut-off point of >= 34 mL/m(2) for LAVI to predict patients with cognitive impairment (sensitivity, 97.1%; specificity, 52.1%; positive predictive value, 49.3%; negative predictive value, 97.4%). LAVI >= 34 mL/m(2) was significantly associated with cognitive impairment (p = 0.001, odds ratio = 36.91, 95% confidence interval = 4.8-284.2). Logistic regression analysis revealed that LAVI >= 34 mL/m(2) and age were independently associated with cognitive impairment. Increased LAVI is associated with cognitive impairment. Assessment of cognitive function may be recommended in elderly patients with enlarged left atria. (C) 2013 Elsevier Ltd. All rights reserved.