Haemodynamic and cardiac metabolic effects of the new beta 1 agonist prenalterol in patients with cardiac failure.

Prenalterol, a beta 1 selective agonist, exerts a positive inotropic action in animal studies as well as in human volunteers and is effective when administered orally. To assess its immediate haemodynamic and myocardial metabolic effects, we studied the response to prenalterol (50 and 100 micrograms kg-1 given intravenously by cardiac catheterization) in 15 patients with congestive heart failure secondary to coronary artery disease or non-ischaemic cardiomyopathy. At peak effect, cardiac index increased from 2.6 +/- 0.5 to 3.2 +/- 0.8 l min-1 m2 (mean +/- S.D.) (P less than 0.001); peak rate of left ventricular pressure development rose from 963 +/- 242 to 1335 +/- 411 mmHg s-1 (P less than 0.001); left ventricular end-diastolic pressure fell from 25 +/- 6 to 17 +/- 7 mgHg (P less than 0.001); coronary sinus blood flow increased from 113 +/- 39 to 148 +/- 55 ml min-1 (P less than 0.01); myocardial oxygen consumption was augmented from 12.7 +/- 3.9 to 16.4 +/- 5.8 ml min-1 (P less than 0.001); and heart rate increased slightly (from 76 +/- 12 to 86 +/- 14 beats min-1; (P less than 0.05)). No significant changes occurred in left ventricular systolic pressure, stroke volume index, myocardial lactate extraction rate and myocardial arteriovenous oxygen difference, and no patients developed angina, ECG changes or ventricular arrhythmias. Infusion of prenalterol effectively improved haemodynamic function and cardiac metabolism in cardiomyopathy. Therefore this agent deserves further investigation to evaluate its possible role for the long-term therapy of patients with chronic heart failure.