Left atrial function: Bridge to central and hormonal determinants of exercise capacity in patients with chronic heart failure

The stroke volume response to exercise is a critical determinant in meeting peripheral metabolic demands in patients with chronic hear failure. The Left atrium, by its position, is important in coupling right and left ventricles, to left preload reserve and to modulate sympathetic activity. We performed this study to investigate the relationship between exercise capacity and diastolic and systolic left atrium function in patients with chronic heart failure. Methods. We considered 128 consecutive patients with severe chronic heart failure (EF <35%) due to ischemic or idiopathic dilated cardiomyopathy. Cardiac output, right atrial pressure, pulmonary artery pressures and mean pulmonary wedge pressure (A, X, V, Y wedge pressures) were determined during right cardiac catheterization. By Echocardiography evaluation, we measured atrial pressures and volume during early and late left atrial systolic filling and we calculated left atrial chamber stiffness by this equation P= A*eKV¹. (P= left atrial pressure; A = elastic constant (mmHg*ml); e = the base of the natural logarithm; V¹ = left atrial volume (ml); K = left atrial chamber stiffness constant (ml^-1) = ln (V/X)/(maximal - minimal left atrial volumes)). All patients performed cardiopulmonary exercise test with modified Noughton protocol. Plasma norepinephrine and Atrial natriuretic factor levels were determined. Results. Maximal and minimal left atrial volumes were inversely related to oxygen consumption (r = -.44, p