Objective - The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of PMI were studied. Design - VCG registrations were obtained from 218 patients undergoing coronary surgery. The spatial QRS vector loop area of each VCG registration was calculated and the loop area before surgery compared with the loop area after surgery. Conventional VCG criteria for myocardial infarction and set values for loop area reduction were related to sustained elevation of plasma troponin-T and clinical course. Results - Both conventional VCG criteria and spatial changes translated better than Q-waves on scalar ECG into elevation of biochemical markers of myocardial injury and impaired clinical course. Conclusion - VCG appears superior to conventional ECG as regards detection of myocardial injury in coronary surgery. Computerized programs have facilitated the registration and the interpretation of VCG and this methodology deserves further evaluation in cardiac surgery.