Perioperative myocardial infarction in coronary artery disease patients and 'at-risk' for coronary artery disease patients undergoing non-cardiac surgery.

ABSTRACT

BACKGROUND: Perioperative myocardial infarction (POMI) carries a high mortality and occurs more commonly in patients with a history of coronary artery disease (CAD). However, there are also other patients undergoing surgery who are 'at risk' for CAD but who do not have a history of infarction or angina. We compared the incidence of POMI in these two groups. METHODS: In a prospective study of 69 men and 39 women over 30 years of age undergoing non-cardiac surgery under general or regional anaesthesia, 56 had definite CAD and 52 were 'at-risk' for CAD. All these patients were followed up with serial postoperative electrocardiography and CK-MB isoenzyme analysis for the diagnosis of POMI. RESULTS: The POMI rate was 32% in definite CAD patients and 15% in patients 'at-risk' for CAD. Mortality in patients with POMI was 17% in those with CAD and 13% in those 'at-risk' for CAD. Perioperative myocardial infarction was maximal in the first 24 hours following surgery (77%). All the POMIs were painless. Anaesthesia techniques--whether regional or general--did not influence the incidence of POMI (Chi-square, p > 0.05). The type of drugs used in the treatment of CAD such as beta-blockers, calcium channel blockers and antiplatelet agents did not cause any difference in the incidence of POMI (Chi-square, p > 0.05). Patients who had either an intraoperative hypertensive episode, tachycardia, arrhythmias or ST-segment changes had a higher incidence of POMI (Chi-square, p > 0.05). The incidence of POMI was not lower in patients undergoing transurethral resection of the prostate compared to patients undergoing other types of non-cardiac surgery (Chi-square, p > 0.05). CONCLUSION: POMI occurs in one-third of patients with a history of CAD and one-sixth of those 'at-risk'. It carries a mortality of 17% and 13% respectively. Decisions to operate on such patients should be taken with caution.