Hemodynamic effects of digoxin in acute myocardial infarction in man: A randomized controlled trial

Abstract

Hemodynamic effects of digoxin in acute myocardial infarction (AMI) have been acknowledged to depend on the basal cardiocirculatory state. In the present study, the effects of digoxin in patients with AMI were evaluated in four hemodynamic subsets, based on the relationship between mean pulmonary capillary wedge pressure (PCWP, in mm Hg) and left ventricular stroke work index (LVSWI, in g-m/m 2): subset 1: normal (≤15 mm Hg) PCWP and normal (≥35 g-m/m 2) LVSWI; subset 2: elevated (>15 mm Hg) PCWP and normal LVSWI; subset 3: reduced (<35 g-m/m 2) LVSWI and normal PCWP; and subset 4: elevated PCWP and LVSWI moderately reduced to a range between 16 and 34 g-m/m 2. Forty patients were admitted to the study and were randomly assigned to one of two groups in each subset: control group (19 patients) and treated group (21 patients). Five patients were randomized into each of the subsets 2, 3, and 4 in both the control and treated groups, while in subset 1 there were four control and six digoxin-treated patients. Control patients were administered a placebo saline solution and digoxin-treated patients received 0.50 mg of the drug intravenously in 20 minutes. The effects of the placebo and of the drug were evaluated at 30, 60, and 90 minutes from the end of the infusion. Hemodynamic data did not vary in the control group, and digoxin did not exert any relevant effect in subsets 1 and 2. After drug infusion, cardiac index (Cl, in L/min/m 2) significantly increased in subset 3 patients. Digoxin markedly improved Cl and reduced mean right atrial pressure and PCWP, along with reduction of triple index and of ECG findings of ischemia in subset 4. It was concluded that digoxin can exert favorable hemodynamic effects during AMI only in patients with moderate left ventricular failure; furthermore, the improved cardiocirculatory state after digitalis in these patients might be associated with a net decrease in myocardial oxygen requirements in spite of enhanced contractility, as a consequence of reduced left ventricular volume and wall tension. The absence of hemodynamic response to digitalis which had been observed in previous studies might have been the consequence of erroneous classification of patients.