Clinical significance of transmural versus nontransmural electrocardiographic changes in patients with acute myocardial infarction

Two hundred thirty patients with probable or definite acute myocardial infarction were observed in a coronary care unit. The electrocardiogram showed changes in the S-T segment and T wave associated with a definitely abnormal enzyme curve in 45 patients (group I), with minimal enzyme rises in 33 patients (group II) and with development of Q waves and evolutionary changes in the S-T segment and T wave in 152 patients (group III). The incidence of supraventricular arrhythmias, ventricular premature beats and primary ventricular tachycardia was similar in all groups. The incidence of shock and mortality rates was similar in groups I (22 and 37 per cent, respectively) and III (18 and 19 per cent, respectively) and significantly greater when compared with group II (3 and 3 per cent, respectively) (p <0.05). There was a significant increase (p <0.05) in maximal serum lactic dehydrogenase (LDH) and serum glutamic oxaloacetic transaminase (SGOT) in patients with severe pump failure when compared to those in patients who had no or mild congestive heart failure. The incidence of severe pump failure and mortality is closely reflected in the magnitude of the enzyme rise but not in the electrocardiographic changes. Although a subset of patients with acute myocardial infarction in whom the prognosis was excellent (group II) was identified, the hazard of arrhythmic deaths (judged by the incidence of premature ventricular contractions and ventricular tachycardia) was similar in all groups.