Evaluation of efficacy of beta blockers administered early in acute myocardial infraction

ABSTRACT

In order to evaluate the efficacy and safety of early intravenous blockers in acute myocardial infarction [AMI], 51 patients with AMI were included and divided into 3 groups. Group 1 [21 patients] who received I.V. Popranolol [P] 0.1 mg/kg, then orally 20 mg in divided doses to keep the heart rate at 60/min. thereafter. Group 2 [10 patients] who received I.V. Metoprolol [M] 15 mg in 3 doses then 100 mg/12 hours orally till discharge, and group 3 [20 patients] who served as control group. No difference was noted between the 3 groups as regards base line to medications,. etc. Chest pain relief was easier in groups 1 and 2 than group 3. Chest pain recurrence was 25% in group 1, 20% in group 2 and 50% in group 3 [P >0.05 + trend]. Infarct extension occurred in 2 patients of control group but no in patients in groups 1 and 2. Ventricular arrhythmia was noted in 21 patients [10%] of group 1, one [10%] of group 2 and 5 [25%] of group 3 [P >0.05 + trend]. Left ventricular failure was noted in 4 patients [20%] of group 1, 2 [20%] of group 2 and 7 [35%] of group 3 [P >0.05 + trend]. Significant reduction of heart rate and blood pressure was noted in groups 1 and 2 versus group 3. Serum CPK level was lower in groups 1 and 2 than in group 3. However, echocardiography failed to identify improved left ventricular function in groups 1 and 2 versus group 3. Despite that the beneficial effects of beta-blockers were not showed to be significant at statistical level in the study [only trends], this may be attributed to the small number of patients in each group. It could be concluded that early use of 4 beta-blockers [P] or [M] is safe and beneficial in AMI resulting in smaller infarct size, less incidence of recurrent angina, infarct extension and lower risk of ventricular arrhythmias