Prognostic importance of postbypass regional wall-motion abnormalities in patients undergoing coronary artery bypass graft surgery

Abstract

Regional wall motion abnormalities (RWMA) detected by intraoperative transesophageal echocardiography (TEE) are thought to be sensitive markers of myocardial ischemia. To assess the prognostic significance of RWMA as compared with other less costly technologies such as electrocardiography (ECG) and hemodynamic measurements [blood pressure (BP) and pulmonary artery (PA) pressure], 50 patients were prospectively studied who were undergoing elective coronary artery bypass graft (CABG) surgery using continuous TEE, ECG (Holter), and hemodynamic measurements during the prebypass, postbypass, and early postoperative intensive care unit (ICU) periods (first 4 h). Echocardiographic and ECG evidence of ischemia was characterized during each of these three periods and related to adverse clinical outcomes (postoperative myocardial infarction, ventricular failure, and cardiac death). Clinicians were blinded to the TEE and ECG information. The prevalence of myocardial ischemia during the perioperative periods was as follows: prebypass, 20% (TEE) versus 7% (ECG); postbypass, 36% (TEE) versus 25% (ECG); ICU 25% (TEE) versus 16% (ECG). Neither prebypass TEE ischemia nor ECG ischemia occurring in any of the three periods predicted adverse outcome. In contrast, postbypass TEE ischemia was predictive of outcome: six of 18 patients with postbypass TEE ischemia had adverse outcomes versus 0 of 32 without TEE ischemia (P = 0.001). Seventy-three percent of the echocardiographic ischemic episodes occurred without acute change (± 20% of control) in heart rate, BP, or PA pressure. The authors conclude that: 1) prebypass myocardial ischemia was relatively uncommon, 2) the incidence of ECG and TEE ischemia was highest in the postbypass period, and 3) postbypass RWMA were related to adverse clinical outcome.