Associations of left atrial volumes and Doppler filling indices with left atrial function in acute myocardial infarction.

Recent findings suggest that left atrial (LA) function is more strongly related to adverse prognosis than LA volumes. We aimed to evaluate the associations between LA volumes and Doppler filling indices with LA function. Echocardiographic LA volumes (LAVs), mitral valve early (MV-E) and late (MV-A) peak flow velocities, and mitral atrioventricular plane tissue-Doppler early (TD-e') and late (TD-a') peak velocities were obtained in 320 patients with acute myocardial infarction (AMI) free from atrial fibrillation and more than moderate valvular disease. LA function was estimated as the LA emptying fraction (LAEF), that is 100× (LAVmax-LAVmin)/LAVmax. LA reservoir volume was calculated as LAVmax-LAVmin and LA transit volume as LV stroke volume-reservoir volume. In restricted cubic spline regression analyses with multivariable adjustment, a reduced LAEF was strongly associated with smaller reservoir volume, larger transit volume, LAVmax, LAVpreA and especially LAVmin. MV-E linearly increased with a lower LAEF, whereas MV-A decreased but only below LAEF levels of approximately 45%. The resulting E/A ratio showed a sudden increase in LAEF levels below ~45%. Lower TD-a' was linearly associated with a lower LAEF. In conclusion, a reduced atrial function was associated with smaller LA reservoir volume, larger LA transit volume, lower TD-a', a non-linear decrease in MV-A and a non-linear increase in E/A. Our findings are likely a reflection of the adaptation to sustain LV filling volume and counteracting a rise in pulmonary venous pressure in face of an enhanced LV end-diastolic pressure.