PREOPERATIVE DIPYRIDAMOLE-THALLIUM IMAGING AND AMBULATORY ELECTROCARDIOGRAPHIC MONITORING AS A PREDICTOR OF PERIOPERATIVE CARDIAC EVENTS AND LONG-TERM OUTCOME

Background: Dipyridamole thallium imaging (DTI) and ambulatory electro cardiography (AEGC) have been advocated as means to stratify risk befo re vascular surgery. The purpose of this study was to compare the pred ictive value of both tests in noncardiac surgery patients for perioper ative cardiac morbidity and long-term mortality, Methods: One hundred eighty patients were referred to the nuclear cardiology laboratory for DTI before noncardiac surgery. In patients with normal electrocardiog rams and who consented, an ambulatory electrocardiogram was recorded f or 24 h. DTI results were classified as negative, positive, or strongl y positive (included in positive). Patients were assessed for a minimu m of 12 months, and Kaplan-Meier cardiovascular survival curves were c onstructed with a log-rank statistic of equality with P < 0.05 signifi cant. Results: One hundred nine patients had both tests and then under went surgery, sustaining 10 perioperative cardiac events (cardiac deat h, myocardial infarction, or symptomatic ischemia). The positive predi ctive values for DTI (18%) and AECG (25%) were similar, as were the li kelihood ratios for positive tests (DTI = 2.1, AECG = 3.3), The likeli hood ratios of a negative test were also similar (DTI = 0.45, AECG = 0 .48), A strongly positive thallium defect had a somewhat greater likel ihood ratio (3.5) for in-hospital events and was the only test result associated with a significantly worse long-term cardiac survival, Conc lusions: AECG and DTI demonstrated a similar, although lower than init ially reported, ability to stratify risk and predict short-term outcom e, Only quantitative dipyridamole thallium also had predictive value f or long-term prognosis.