Myocardial infarction following surgical operations.

One hundred and forty-one randomly selected surgical patients, aged 35 years or over, were studied preoperatively, followed through their operative procedures, and reassessed during the first post-operative week for evidence of myocardial ischaemia associated with surgical operations under general anaesthesia. Of these patients 38% were found to have preoperative clinical evidence of heart disease, hypertension, or diabetes; 45% had abnormal preoperative E.C.G. patterns.Three patients experienced myocardial infarction during or within 36 hours of operation, all of the occult type; all were in the preoperative abnormal groups. Non-specific postoperative E.C.G. changes were equally common in the groups of patients with normal or abnormal preoperative electrocardiograms.A relationship existed between a rise in serum lactic dehydrogenase (L.D.H.) concentration and the field of the operation, but the diagnosis of infarction was not confused provided serum L.D.H. isoenzyme patterns and a rise in serum aspartate aminotransferase (S.G.O.T.) levels were consistent with the diagnosis.