Clinical and haemodynamic responses to captopril and hydralazine in chronic congestive heart failure: the importance of preload reduction.

1 Although many vasodilators are effective in the treatment of severe congestive heart failure, there have been few comparative studies of these drugs. We compared the acute haemodynamic effects of captopril and hydralazine in 11 patients with congestive cardiac failure unresponsive to diuretics and digoxin. Both drugs increased resting cardiac index, although this effect appeared more pronounced for hydralazine (33% v 23%). Captopril reduced pulmonary capillary wedge pressure (-8 mm Hg, p < 0.01) which decreased only slightly on hydralazine. 2 Long-term treatment was then started on the dose found effective during acute administration. Each drug was given for eight weeks. Exercise tolerance improved with both drugs, the increase during the hydralazine phase correlating with the increase in cardiac index at rest (r = 0.75; p < 0.05). Clinical improvement appeared more definite on captopril than on hydralazine, however. This improvement was maintained during the captopril phase only in those patients who had a greater than 25% reduction in pulmonary capillary wedge pressure in the acute study.