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 ≤ 4.0m/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 & LAmin 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)-LAmin 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), LAmin volume 17.9 ± 9.3 mL/m(2), LA-EF 50 ± 15% and LA(con) volume 45 ± 21 mL/m(2). Baseline LAmin 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 LAmin volume was superior to all other LA measurements. Net reclassification index improved by 15.9% when adding LAmin volume to a model with classic risk factors for AF (P=0.01).

CONCLUSION

LAmin 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.