PREDICTIVE VALUE OF DOBUTAMINE ECHOCARDIOGRAPHY JUST BEFORE NONCARDIAC VASCULAR-SURGERY

This study prospectively evaluated 75 consecutive patients (mean age 6 9 +/- 9 years) undergoing major vascular surgery to test the hypothesi s that dobutamine stress echocardiography can be used to predict perio perative cardiac events. A positive test was defined as a new or worse ning wall motion abnormality in at least 2 of 18 wall segments. Up to 40 mug/kg/min of dobutamine was administered. All readings were done b y physicians unaware of the patients; symptoms and electrocardiographi c response. In addition, physicians caring for the patients were unawa re of the test result. End points of the study were unstable angina wi th documented electrocardiographic changes, nonfatal myocardial infarc tion or cardiac death. The perioperative ischemic event rate was 7% (5 of 75 patients). Three patients developed unstable angina and 2 susta ined nonfatal myocardial infarctions. All of these patients had positi ve results on dobutamine stress echocardiography (sensitivity 100%). H owever, 22 patients who also had positive results on dobutamine stress echocardiography did not have perioperative events (specificity 69%). The corresponding positive predictive value was 19%. Nons of the 48 p atients who had negative results on dobutamine stress echocardiography had events (negative predictive value 100%). In conclusion, dobutamin e stress echocardiography can be used to predict perioperative events with great sensitivity, but its positive predictive value in this pati ent population is low, likely due to the low incidence of perioperativ e events in patients with known coronary artery disease and the imperf ect specificity of dobutamine stress echocardiography in identifying s ignificant coronary stenosis. Dobutamine stress echocardiography is mo st useful in this setting when negative, because it predicts safety fr om complications with confidence.