Benefits of central sympathetic suppression with clonidine after acute myocardial infarction

This study assessed the safety and tolerability of clonidine in patients wi th acute anterior myocardial infarction (AMI) and tested the effect of cent ral sympathetic suppression on myocardial damage, arrhythmias, and outcome. Twenty-four previously untreated patients with a first AMI receiving stand ard therapy including thrombolysis were randomly divided into group 1 (n = 11, control) and group 2 (n = 13, added oral clonidine .075 mg twice daily for 1 week). Plasma renin activity (PRA), norepinephrine (NE), epinephrine (E), arginine-vasopressin (AVP), and enzyme levels were measured, and elect rocardiography was performed before and after thrombolysis at 2, 24, and 48 hours. Holter monitoring was performed during the first 24 hours and echoc ardiography at 1 week. Baseline values were similarly high in the two group s and declined in both over time, but group 2 had significantly lower NE le vels at 2 hours (P<.02) that remained virtually the same at 24 and 48 hours , lower PRA at 48 hours (P<.03), and lower AVP levels at 2 hours (P<.03). A ll other values also tended to decrease to a greater extent in group 2, inc luding ventricular tachycardia runs at 1 week. Ejection fraction, however, was higher in the clonidine-treated patients (P<.07). Three patients who di ed, all from group 1, experienced an initial decline of NE at 2 hours that rose sharply thereafter. Clonidine given immediately post-AMI is well toler ated, suppresses neurohormone levels, and may improve survival.