Prazosin and captopril in chronic heart failure: comparison of acute haemodynamic and hormonal effects

Ten patients with severe chronic heart failure were given prazosin 5 mg and captopril 25 mg in random order on consecutive days. Small increases in cardiac index and reductions in heart rate were effected by both drugs, but these alterations and the accompanying increases in stroke volume index were significant only following captopril. Both drugs significantly reduced mean pulmonary capillary wedge pressure and mean right atrial pressure and also systemic vascular resistance and blood pressure, the effect of captopril being greater than that of prazosin. Following captopril, plasma aldosterone levels were significantly reduced and plasma renin activity increased from control values, whereas prazosin did not alter these hormone indices.