ECHOCARDIOGRAPHY FOR ASSESSING CARDIAC RISK IN PATIENTS HAVING NONCARDIAC SURGERY

Background: Cardiac complications after noncardiac surgery are a serio us cause of illness and death. Echocardiography is being used before n oncardiac surgery to assess risk for cardiac complications, but its ro le remains undefined. Objective: To examine the prognostic value and o perating characteristics of transthoracic echocardiography for assessi ng cardiac risk before noncardiac surgery. Design: Prospective cohort study. Setting: University-affiliated Veterans Affairs medical center. Patients: 339 consecutive men who were known to have or were suspecte d of having coronary artery disease and were scheduled for major nonca rdiac surgery. Measurements: Information from detailed histories, phys ical examinations, and electrocardiographic and laboratory studies was routinely collected. Transthoracic echocardiography was done before s urgery to assess ejection fraction, wall motion abnormalities (reporte d as the wall motion score [range, 5 to 25 points]), and left ventricu lar hypertrophy. Main Outcome Measures: Postoperative ischemic events (cardiac-related death, nonfatal myocardial infarction, and unstable a ngina), congestive heart failure, and ventricular tachycardia. Results : 10 patients (3%) had ischemic events; 26 (8%) had congestive heart f ailure; and 29 (8%) had ventricular tachycardia. No echocardiographic measurements were associated with ischemic events. In univariate analy ses, an ejection fraction less than 40% was associated with all cardia c outcomes combined (odds ratio, 3.5 [95% CI, 1.8 to 6.7]), congestive heart failure (odds ratio, 3.0 [CI, 1.2 to 7.4]), and ventricular tac hycardia (odds ratio, 2.6 [CI, 1.1 to 6.2]). In multivariable analyses that adjusted for known clinical risk factors, an ejection fraction l ess than 40% was a significant predictor of ail outcomes combined (odd s ratio, 2.5 [CI, 1.2 to 5.0]) but not congestive heart failure (odds ratio, 2.1 [CI, 0.7 to 6.0]) and ventricular ejection fraction (odds r atio, 1.8 [CI, 0.7 to 4.7]). Wall motion score was a univariate predic tor of all cardiac outcomes (odds ratio for each 3-unit increase, 1.6 [CI, 1.3 to 2.1]) and ventricular tachycardia (odds ratio, 1.6 [CI, 1. 2 to 2.2]) but was only a multivariable risk factor for all events (od ds ratio, 1.3 [CI, 1.0 to 1.7]). An ejection fraction less than 40% ha d a sensitivity of 0.28 to 0.31 and a specificity of 0.87 to 0.89 for all categories of adverse outcomes. Likelihood ratios for ejection fra ction had poor operating characteristics. Adding echocardiographic inf ormation to predictive models that contained known clinical risk facto rs did not alter sensitivity, specificity, or predictive values in cli nically important ways. Conclusions: The data did not support the use of transthoracic echocardiography for the assessment of cardiac risk b efore noncardiac surgery. Echocardiographic measurements had limited p rognostic value and suboptimal operating characteristics.