LIMITED USEFULNESS OF EXERCISE TESTING AND THALLIUM SCINTIGRAPHY IN EVALUATION OF AMBULATORY PATIENTS SEVERAL MONTHS AFTER RECOVERY FROM ANACUTE CORONARY EVENT - IMPLICATIONS FOR MANAGEMENT OF STABLE CORONARYHEART-DISEASE

Objectives. This study evaluated the value of noninvasive test- ing to predict cardiac events in patients with stable coronary disease after hospital admission (and risk stratification) for an acute coronary ev ent. Background. Exercise testing with thallium perfusion imaging iden tifies patients with obstructive coronary artery disease and has been used to stratify patients after myocardial infarction. Its usefulness for predicting cardiac events in patients with stable coronary disease after recovery from an acute coronary event was explored. Methods. Ni ne hundred thirty-six patients were enrolled 1 to 6 months after hospi tal admission for a coronary event. Patients underwent exercise treadm ill testing with planar thallium-201 scintigraphy and were followed up for an average of 23 months (range 6 to 43). End points were 1) unsta ble angina requiring hospital admission, nonfatal myocardial infarctio n or cardiac death; 2) nonfatal infarction or cardiac death; or 3) car diac death alone. Results. Twelve patients died of cardiac causes (1.2 %); 32 had a nonfatal myocardial infarction (3.4%); and 79 patients (8 .4%) devel- oped unstable angina in the first year. Exercise testing i mproved proportional hazards models constructed from clinical variable s for all three end points (p < 0.05). The perfusion scan further impr oved models for the end points (nonfatal infarction or cardiac death a nd cardiac death alone, p < 0.05). However, the exercise test with or without thallium added little to the overall prediction of primary eve nts (area under the receiver operating curve increased from 0.649 to 0 .663), and only 2% to 13% of patients with abnormal results either had a nonfatal infarction or died. Conclusions. Thallium-201 scintigraphy and exercise testing variables identify patients at risk for subseque nt cardiac events. However, the poor predictive performance of these t ests in this group of patients with stable coronary disease severely l imits their usefulness. These results suggest a limited role for exerc ise and thallium testing in predicting cardiac events in patients with known coronary disease.