The Responsibility of Left Atrial Size and Wall Contraction Velocity to Left Atrial Active Emptying in Relation to the Mitral Flow Velocity Pattern

The aim of this study was to investigate the role and limitations of left atrial (LA) preload or contractility as determinants of active LA emptying in patients with heart failure. In 56 healthy individuals (controls) and 30 patients with heart failure, the LA volume before atrial contraction (LAV(pre) I), the LA volume reduction (LASVI) and LA wall contraction velocity (LAWV) during atrial contraction, and the transmitral peak flow velocities during early diastole (E) and atrial contraction (A) were determined using two-dimensional pulsed Doppler or tissue Doppler echocardiography. LAV(pre) I and LASVI were positively correlated in patients whose A/E ratio was ≥1 (r = 0.58) and negatively correlated in those whose A/E ratio was <1 (r =-0.63). LAWV was significantly lower in those with heart failure than in the controls 2.2 (1.2) cm/sec, versus 3.3 (0.8) cm/sec; mean (standard deviation) and negatively correlated with left ventricular end-diastolic pressure (r =-0.37). LAWV and LASVI were significantly correlated (r = 0.71). This correlation was stronger in the patients whose A/E ratio was <1 than in those whose A/E ratio was ≥1. Multivariate regression analysis showed that LAWV was the only factor affecting LASVI. In patients with heart failure and an A/E ratio of <1, the contribution of LA dilatation to active LA emptying may be limited, and LAWV may be the most important determinant of active LA emptying, even if this velocity is decreased because of elevated left ventricular diastolic pressure.