Intravenous Clonidine Treatment in Acute Myocardial Infarction (with Comparison to a Nitroglycerin-Treated and Control Group)

Abstract

This study describes the effects of intravenous clonidine treatment in a group of 24 patients with acute myocardial transmural anterior and/or lateral wall infarction. Clonidine was administered as a bolus injection of 1-2 µg/kg body weight and repeated every 1-3 h. The range of the time of administration varied from 20 min to 4 h, with the maximal range of doses from 37 to 150 µg, depending on the hemodynamic status. The effects were measured by precordial electrocardiographic mapping and compared with similar effects obtained in the nitroglycerin-treated group (30 patients) and a control group (12 patients). A large decrease in ST segment elevation was observed. The ST reduction after 24 h was 37% of initial value (compared with 52% in the nitroglycerin group, 140% in the control group); after 48 h there was a 30% reduction (compared with 55% in the nitroglycerin group and 120% in the control group). After 24 h there was a fall in NST of 45% (71% with nitroglycerin and 145% in the control group); after 48 h there was a 41% decrease (compared with 65% in the nitroglycerin group and 142% in the control group). New Q waves increased after 24 h to 135% of the initial value (compared with 122% in the nitroglycerin group and 156% in the control group); after 72 h this increased to 137% (128% in the nitroglycerin group and 167% in the control group). Detailed analysis revealed a correlation between the dosage and favorable dynamics of mapping parameters. Hemodynamic, antiarrhythmic, and, in particular, adrenolytic activity were noted. The clonidine treatment caused a distinct deterioration in daily adrenalinuria mean values to 5.99 µg in the first day (control 14.20) and even lower in the following days. A temporal association between diminished adrenalinuria and a clinical improvement and limitation of infarct size was also observed. Therapy with intravenous clonidine requires meticulous attention to the dosage depending on the individual patient's hemodynamic status.