ARE ELECTROCARDIOGRAPHIC Q-WAVE CRITERIA RELIABLE FOR DIAGNOSIS OF PERIOPERATIVE MYOCARDIAL-INFARCTION AFTER CORONARY SURGERY

Objective: A major assumption in cardiovascular medicine is that Q-wav es on the electrocardiogram indicate major myocardial tissue damage. T he appearance of a new Q-wave has therefore been considered the most r eliable criterion for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery. In a study, originally intended to evaluate troponin-T as a marker of PMI, analysis of our data aroused the need to address the reliability of Q-wave criteria for diagnosis of PMI. Me thods: In 302 consecutive patients undergoing coronary surgery, Q-wave and other electrocardiogram (ECG) criteria were compared with biochem ical markers of myocardial injury and the postoperative course. All EC Gs were analysed by a cardiologist blinded to the biochemical analyses and the clinical course. Results: The incidence of positive Q-wave cr iteria was 8.1%. Combined biochemical (CK-MB greater than or equal to 70 mu g/l) and Q-wave criteria were found in 1.0%. Patients with new Q -waves did not have CK-MB or troponin-T levels significantly different from those without Q-waves. More than 25% of the Q-waves were associa ted with plasma troponin-T below the reference level (<0.2 mu g/l) on the fourth postoperative day. Q-wave criteria alone did not influence the postoperative course. In contrast, biochemical markers correlated with clinical outcome. Conclusions: The majority of Q-waves appearing after coronary surgery were not associated with major myocardial tissu e damage, and according to troponin-T one-fourth of the Q-waves were n ot associated with myocardial necrosis. Furthermore, the appearance of Q-waves had little influence on short term clinical outcome. Therefor e, the use of Q-wave criteria as the gold standard for diagnosis of PM I may have to be questioned. (C) 1998 Elsevier Science B.V. All rights reserved.