Positive inotropic therapy for short-term support and long-term management of patients with congestive heart failure: hemodynamic effects and clinical efficacy of MDL 17,043.

The positive inotropic/vasodilator agent MDL 17,043 was evaluated to determine its usefulness for both short-term support of the failing circulation and long-term treatment of patients with congestive heart failure. Both intravenous and oral administration of MDL 17,043 significantly increased cardiac output, stroke volume, stroke work index, and heart rate, and significantly decreased pulmonary arterial wedge, right atrial, and mean arterial pressures as well as systemic and pulmonary arteriolar resistance. Such hemodynamic responsiveness persisted in patients on long-term oral therapy with MDL 17,043. When compared with dobutamine, the peak hemodynamic effects of MDL 17,043 were similar except for somewhat greater increases in heart rate with dobutamine and somewhat greater decreases in mean pulmonary arterial and wedge pressures with MDL 17,043. Both intravenous and oral MDL 17,043 elevated plasma renin activity. Oral doses were rapidly absorbed, and the drug had an elimination half-life of about 20 hr. Although the majority of patients showed clinical improvement at 1 month, this effect tended to wane over time leading to either recurrent heart failure or death. Mortality rates at 1 year are about 46% in class III patients and 97% in class IV patients on long-term oral MDL 17,043. The results of these studies suggest that MDL 17,043 may be useful in the short-term management of the failing circulation; however, its value in the long-term management of patients with chronic heart failure remains unclear and requires further studies for resolution.