Left atrial size and function as predictors of new-onset of atrial fibrillation in patients with asymptomatic aortic stenosis: The simvastatin and ezetimibe in aortic stenosis study

Background: Left atrial (LA) size and function change with chronically increased left ventricular (LV) filling pressures. It remains unclear whether these variations in LA parameters can predict new-onset atrial fibrillation (AF) in asymptomatic patients with aortic stenosis (AS). Methods: Data were obtained in asymptomatic patients with mild-to-moderate AS (2.5 <= transaortic Doppler velocity <= 4.0 m/s), preserved LV ejection fraction (EF), no previous AF, and were enrolled in the Simvastatin and Ezetimibe in Aortic Stenosis study. Peak-aortic velocity, LA(max) volume & LA(min) volume were measured by echocardiography. LA conduit (LA(con)) volume was defined as LV stroke volume-LA stroke volume. LA function was expressed as LA-EF (LA(max)-LA(min) volume/LA(max)). Results: In the 1159 patients included, new-onset AF occurred in 71 patients (6.1%) within a mean follow-up of 4.2 +/- 0.9 years. Mean age was 66 +/- 9.7 years, aortic valve area index 0.6 +/- 0.2 cm(2)/m(2), LV mass 99.2 +/- 29.7 g/m(2), LA(max) volume 34.6 +/- 12.0 mL/m(2), LA(min) volume 17.9 +/- 9.3 mL/m(2), LA-EF 50 +/- 15% and LA(con) volume 45 +/- 21 mL/m(2). Baseline LA(min) volume predicted new-onset AF in Cox multivariable analysis (HR: 2.3 [ 95% CI: 1.3-4.4], P<0.01), and added prognostic information on AF development beyond conventional risk factors (likelihood ratio, P<0.01). In comparison of c-indexes LA(min) volume was superior to all other LA measurements. Net reclassification index improved by 15.9% when adding LA(min) volume to a model with classic risk factors for AF (P=0.01). Conclusion: LA(min) volume independently predicted new-onset AF in patients with asymptomatic AS and was superior to LA-EF, LA(con) and LA(max) volumes and conventional risk factors. (C) 2013 Elsevier Ireland Ltd. All rights reserved.