Hemodynamic assessment of prenalterol: a cardioselective beta agonist in patients with imparied left ventricular function.

The hemodynamic effects of a new cardioselective beta agonist, prenalterol, were evaluated in 12 patients with moderate or severe impairment of left ventricular function due to coronary heart disease or primary cardiomyopathy. In doses up to 7 mg the drug led to a substantial increase of left ventricular pressure rise (+55%) and mean circumferential fiber shortening (+59%) and a decrease of left ventricular end-diastolic pressure (-52%), mean pulmonary artery pressure (-24%) and pulmonary vascular resistance (-37%) indicating augmented myocardial contractility and reduced left ventricular preload. Cardiac output was increased only in 4 of 12 patients, heart rate, left ventricular systolic and mean right atrial pressures and the pressure-rate product as an index for myocardial oxygen demand remained essentially unchanged. The same is true for stroke index, stroke work index, total peripheral resistance, left ventricular end-diastolic and end-systolic volume and ejection fraction. The positive inotropic effect was achieved with good tolerance and without arrhythmogenic or other side effects. Prenalterol may be especially useful in patients with low sympathetic activity and hypotension. In patients with diffuse congestive cardiomyopathy, high sympathetic activity, pronounced peripheral vasoconstriction and normal blood pressure, vasodilator therapy alone or in combination with prenalterol should be considered.