Alterations in left ventricular function and coronary hemodynamics with captopril, hydralazine and prazosin in chronic ischemic heart failure: a comparative study.

In 14 patients with chronic heart failure, changes in coronary hemodynamics, myocardial metabolism and left ventricular function were evaluated after administration of captopril, prazosin and hydralazine. Eleven patients received captopril in incremental doses (6.25-150 mg) until the arterial pressure decreased by 10 mm Hg; 11 patients received prazosin (5 mg) and 10 patients received hydralazine (100 mg). The control hemodynamics and metabolic variables before each drug trial were similar. All three vasodilators increased cardiac index (captopril 19%, p < 0.001; prazosin 29%, p < 0.001; hydralazine 36%,p < 0.001), and decreased the pulmonary capillary wedge pressure (captopril 24 ± 6 to 17 ± 6 mm Hg, p < 0.001; prazosin 20 ± 7 to 13 ± 6 mm Hg,p < 0.001; hydralazine 19 ± 8 to 16 + 7 mm Hg,p < 0.025), indicating improved left ventricular function with all three agents. The average rate-pressure product decreased after captopril and prazosin by 27% and 14%, respectively, but only captopril decreased the myocardial oxygen consumption significantly (19%, p < 0.025). There was myocardial lactate production, indicating ischemia, in one patient with captopril, two patients with prazosin and two patients with hydralazine. These results suggest that only captopril consistently improves left ventricular function at a decreased metabolic cost. Despite improved hemodynamics and left ventricular function, metabolic function can deteriorate during vasodilator therapy in some patients with chronic ischemic heart failure.