Haemodynamic effects of a new β1-receptor agonist in acute myocardial infarction. A useful antidote to unwanted cardiac effects of β-blocking agents

Abstract

The haemodynamic effects of a new β1-receptor agonist, 1-(4 hydrophenoxy) 3-isopropyl amino-2-propanol, were studied in 25 patients after acute myocardial infarction using non-invasive methods. The drug caused an increase in systolic blood pressure and pulse pressure, without change in diastolic blood pressure, and a slight increase in heart rate and reduction in the pre-ejection period. These changes were greater in patients without a history of left heart failure. It is suggested that this cardioselective drug possesses positive inotropic activity but only slight positive chronotropic activity. The substance has been further investigated as a possible antidote to unwanted cardiac side effects of the cardioselective β-blocker, metoprolol. The changes in the cardiovascular dynamics caused by metoprolol in patients with acute myocardial infarction were promptly reversed by this new β1-agonist. With its positive inotropic properties and its efficacy in reversing the effects of a cardioselective β-blocker, the drug is a potentially useful pharmocological agent to support an acutely depressed myocardium in patients on β-blocking agents.