The haemodynamic effects of
prenalterol, a new beta-1 agonist, were studied in 10 patients with chronic
heart failure. Following intravenous
prenalterol infusions of 1 mg, 2.5 mg and 5 mg at 15 min intervals, oral slow release
prenalterol 20 mg, 30 mg and 50 mg was given at 2 h intervals and then 50-100 mg bid for one month. There were no significant changes in heart rate or blood pressure. Cardiac output increased significantly from control of 4.4 +/- 0.91/min to a maximum of 5.8 +/- 1.81/min (p less than 0.01) following the 5 mg
prenalterol infusion and this increase was maintained following oral
prenalterol on Days 1 and 2 and at 1 month. Significant increases in stroke volume and
stroke work indices and reduction in systemic vascular resistance were also observed. Maximum increases in cardiac output and
stroke work index following intravenous
prenalterol correlated significantly with maximum increases observed following oral
prenalterol on Day 2. Non-invasive evaluation showed no change in echocardiographic left ventricular end-diastolic dimension but a significant reduction in left ventricular end-systolic dimension on Day 30. PEP/LVET was significantly reduced from control of 0.56 +/- 0.15 to 0.47 +/- 0.12 (p less than 0.05) on Day 2 and 0.49 +/- 0.09 (p less than 0.05) at 1 month. Treadmill exercise duration was significantly improved for the group at 1 month and no adverse effects were noted. Oral slow release
prenalterol is a potentially useful new
drug for patients with chronic
heart failure.