First-Line Treatment of Left Ventricular Failure Complicating Acute Myocardial Infarction: A Randomised Evaluation of Immediate Effects of Diuretic, Venodilator, Arteriodilator, and Positive Inotropic Drugs on Left Ventricular Function

A prospective randomised trial compared the immediate haemodynamic effects of intravenous diuretic (frusemide), venodilator (isosorbide dinitrate). arteriolar dilator (hydralazine), and positive inotropie stimulation (prenalterol) as first-line therapy for acute left ventricular (LV) failure following myocardial infarction. Forty-eight patients with transmural myocardial infarction and a pulmonary artery occluded pressure (PAOP) of >20 mm Hg were studied within 18 h of admission to a coronary care unit. Both frusemide (-4 mm Hgp < 0.01) and isosorbide dinitrate (-6 mm Hgp < 0.01) reduced LV filling pressure without change in cardiac index and heart rate. Although both hydralazine and prenalterol increased cardiac index (p < 0.01), the reduction in LV filling pressure (-2 mm Hgp < 0.05) was less than with frusemide and isosorbide dinitrate. and was associated with an increased heart rate (+8 and + 13 beats minp < 0.01). These data suggest that in acute heart failure following myocardial infarction the four treatment modalities could be ranked in descending order of potential benefit as follows(a) venodilatation (isosorbide dinitrate) — decrease of LV pressure/work(b) diuretic therapy (frusemide)— decrease of LV pressure/work offset by a transient pressor effect(c) arteriolar dilatation (hydralazine) —decrease of LV pressure/work and of PAOP. but offset by tachycardiaand (d) positive inotropic therapy (β1-agonist prenalterol) — tachycardia and augmented LV afterload. Combination of the former and latter agents, because of their differing modes of action, should offer haemodynamic advantages over monotherapy and deserves further evaluation.