Clinical significance of a new Q wave after cardiac surgery

Objective: The appearance of new Q waves on the electrocardiogram (ECG) after cardiac surgery has been traditionally considered a sign of major myocardial tissue damage. The aim of this study was to investigate the clinical significance of new Q waves appearing following cardiac surgery and to correlate them with the release of myocardial cell damage biomarkers. Methods: 206 consecutive patients undergoing cardiac surgery were prospectively evaluated. A 12 lead ECG was recorded and cardiac troponin I and creatinekinase subfraction MB assayed the day before surgery, on arrival at the intensive care Unit. 4 and 18 h postoperatively and every morning until the fifth postoperative day. Results: The incidence of new Q waves was 7.3%. Patients with isolated ECG findings had an uneventful postoperative course; on the contrary, when ECG changes were coupled with the release of myocardial necrosis biomarkers, patients had a complicated postoperative course. Conclusions: The association of a new Q wave and high levels of myocardial necrosis biomarkers is strongly associated with postoperative cardiac events. On the contrary, the isolated appearance of a new Q wave has no impact on the postoperative cardiac outcome.