ADDITIVE VALUE OF THALLIUM SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHYMYOCARDIAL IMAGING FOR PREDICTION OF PERIOPERATIVE EVENTS IN CLINICALLY SELECTED HIGH CARDIAC RISK PATIENTS HAVING ABDOMINAL AORTIC-SURGERY

The present study was designed to prospectively evaluate whether reinj ection thallium-201 single-photon emission computed tomography (SPECT) has a significant additive predictive value for occurrence of periope rative cardiac events in clinically selected patients at high cardiac risk undergoing abdominal aortic surgery. Of a group of 517 consecutiv e patients referred, 134 had greater than or equal to 2 of the-followi ng clinical or electrocardiographic cardiac risk variables: age >70 ye ars; history of myocardial infarction, angina, or congestive heart fai lure; diabetes mellitus; hypertension with severe left ventricular hyp ertrophy; and Q waves or ischemic ST-segment abnormalities on electroc ardiogram at rest. Operation was performed after thallium SPECT study. Twelve patients (9%) had major perioperative events (cardiac death or nonfatal myocardial infarction) and 18 patients had other cardiac eve nts (unstable angina, heart failure, or severe ventricular tachyarrhyt hmia). Variables correlated with the occurrence of major events were h istory of myocardial infarction (p <0.05) and the presence (p<0.001) a nd number of segments with thallium reversible defects (p <0.001). In multivariate analysis, history of myocardial infarction (p <0.05) and the number of segments with reversible thallium defects (p <0.001) wer e independent predictors. When all the cardiac events were taken into consideration, all the previous variables, as well as Q waves and isch emic ST abnormalities on the electrocardiogram, showed significant pre dictive value in both univariate and multivariate analyses. furthermor e, thallium SPECT imaging has an additive predictive value for major c ardiac events over clinical and electrocardiographic risk factors. Whe n performed on clinically selected patients at high cardiac risk under going abdominal aortic surgery, thallium SPECT demonstrates significan t prognostic value for cardiac events over that provided by clinical v ariables alone.