Intra-operative myocardial ischaemia and infarction in patients with coronary artery disease undergoing...

Fifty patients over the age of 40 years of either sex (28 males and 22 females) having definite coronary artery disease as indicated by history of previous myocardial infarction, angina or ECG evidences of myocardial infarction (silent myocardial infarction), undergoing non-cardiac surgery were studied. In order to detect the incidence of myocardial ischaemia during the peri-operative period, continuous monitoring of electrocardiogram was performed in all patients for 24 hours, beginning from the morning of surgery using a 2-channel Holter recorder. Intra-operative events besides myocardial ischaemia were noted. CK-MB isoenzyme assay was done on days 0, 1, 2, 3, 5, 7 postoperatively in all patients. CK-MB and ECG were also done whenever indicated. The incidences of intra-operative and postoperative ischaemia were 40% and 48% respectively. The incidence of postoperative myocardial ischaemia in patients with intra-operative myocardial ischaemia was found to be significantly higher than those patients without intra-operative myocardial ischaemia. The rate of myocardial ischaemia and peri-operative myocardial infarction was lower in patients on beta-blockers than those patients who were not on these drugs though a statistical difference was not reached. The rate of peri-operative myocardial infarction was also found to be higher in patients who had intra-operative hypertensive or hypotensive episodes though a statistical significance was not reached. Patients who had either pre-operative or peri-operative myocardial ischaemia had greater incidence of peri-operative myocardial infarction than those patients without myocardial ischaemia but the difference was not statistically significant.