ELECTROCARDIOGRAPHIC AND HEMODYNAMIC-CHANGES AND THEIR ASSOCIATION WITH MYOCARDIAL-INFARCTION DURING CORONARY-ARTERY BYPASS-SURGERY - A MULTICENTER STUDY

Background: Electrocardiographic (ECG) changes during coronary artery bypass graft surgery have not been described in detail in a large mult icenter population. The authors describe these ECG changes and evaluat e them, along with demographic and clinical characteristics and intrao perative hemodynamic alterations, as predictors of myocardial infarcti on (MI) as defined by two sets of criteria. Methods: Data from 566 pat ients at 20 clinical sites, collected as part of a clinical trial to e valuate the efficacy of acadesine for reducing MI, were analyzed at co re laboratories, Perioperative ECG changes were identified using conti nuous three-lead Holter ECG. Systolic blood pressure, diastolic blood pressure, and heart rate were recorded each minute during operation. T he occurrence of MI by Q wave or myocardial fraction of creatine kinas e (CK-MB) or autopsy criteria, and by (Q wave and CK-MB) or autopsy cr iteria was determined. Results: During perioperative Holter monitoring , episodes of ST segment deviation, major cardiac conduction changes g reater than or equal to 30 min, or use of ventricular pacing greater t han or equal to 30 min occurred in 58% patients, primarily in the firs t 8 h after release of aortic occlusion. Of the 25% patients who met t he Q wave or CK-MB or autopsy criteria for MI, 19% had increased CK-MB as web as ECG changes, (Q Rave and CK-MB) or autopsy criteria for MI were met by 4% of patients, The CK-MB concentration generally peaked b y 16 h after release of aortic occlusion. In patients with (n = 187) a nd without a perioperative episode of ST segment deviation, the incide nce of MI was 36% and 19%, respectively (P < 0.01), by Q wave or CK-MB or autopsy criteria, and 6% and 3%, respectively (P = 0.055), by (Q w ave and CK-MB) or autopsy criteria. Multiple logistic regression analy sis showed that intraoperative ST segment deviation, intraventricular conduction defect, left bundle branch block, duration of hypotension ( systolic blood pressure < 90 mmHg) after cardiopulmonary bypass, and d uration of cardiopulmonary bypass are independent predictors of Q wave or CK-MB or autopsy MI. The independent predictors of (Q wave and CK- MB) or autopsy MI are intraoperative ST segment deviation and duration of aortic occlusion. Conclusions: Major ECG changes occurred in 58% o f patients during coronary artery bypass graft surgery, primarily with in 8 h after release of aortic occlusion. Multicenter data collection revealed a substantial variation in the incidence of MI and an overall incidence of up to 25%, with most MI occurring within 16 h after rele ase of aortic occlusion. Intraoperative monitoring of ECG and hemodyna mics has incremental value for predicting MI.