[Changes on release of MB isoenzyme of creatine kinase by propranolol in acute myocardial infarction (author's transl)].

MB isoenzyme of creatine kinase was measured every 3 hours during the first 24 hours of admission to C.C.U. and successively every 4-6 hours in the next 24-48 hours in 42 patients with acute transmural myocardial infarction. The pain-C.C.U. admission time interval was less than 6 hours in all cases. 22 patients were treated by propranolol (2 mg bolus followed by 0.1 mg/Kg/die for the next 48 hours in continuous i.v. infusion), 20 patients served as a control. Cumulated activity, peak plasma value, rate of release and total duration of release of MB-CK did not differ significantly between the two groups. In patients treated within 3 hours from pain onset (n = 12) cumulated activity, peak plasma value and rate of release of MB-CK were significantly inferior than control group. In patients treated between the 3rd and 6th hour from pain onset (n = 10) the total duration of release of isoenzyme was significantly prolonged. No treated patients developed clinical or radiologic signs of cardiac insufficiency. The incidence of ventricular arrhythmias was 17% in the treated group vs. 62% in the control group (P < 0.05). The data show that propranolol, if started early in the course of acute myocardial infarction, reduces significantly infarct size and slows down the evolution of necrotic process.