Contractile, coronary, and metabolic effects of the acute and long-term treatment of cardiac failure with prenalterol.

Prenalterol was examined with regard to its acute intravenous effects on left ventricular function, coronary hemodynamics, and myocardial oxygen consumption, as well as for its long-term effects, by oral therapy, on left ventricular function and systemic hemodynamics. Intravenous prenalterol enhances myocardial contractility and left ventricular ejection function significantly. A decrease in total peripheral vascular resistance is effected. Myocardial oxygen consumption is only moderately increased, most probably because of the decrease in the systolic integrated wall stress of the left ventricle. The changes of coronary circulation (blood flow, resistance, arteriovenous, oxygen difference) indicate benign and metabolically induced coronary vasodilation. Long-term oral treatment of patients with severe cardiac failure by prenalterol effects significant enhancement in-left ventricular performance within the first 1-2 months of treatment; however, this effect is not present at longer therapy intervals (16-28 weeks). Tolerance development as well as the natural history of these patients may be responsible for this inotropic amelioration. There were no clinical side effects with either intravenous or oral application. It may be concluded that prenalterol is highly effective in acute cardiac failure (intravenous administration) and also in chronic heart disease (long-term oral application). However, the long-term effects are unpredictable, and tolerance development has to be considered.