PROGNOSTIC-SIGNIFICANCE OF EXERCISE TL-201 MYOCARDIAL PERFUSION IMAGING COMPARED TO STRESS ECHOCARDIOGRAPHY AND CLINICAL-VARIABLES IN PATIENTS WITH UNSTABLE ANGINA WHO RESPOND TO MEDICAL-TREATMENT

The prognostic value of thallium-201 imaging in patients with unstable angina is not well established. Forty consecutive patients with unsta ble angina who had responded to medical therapy underwent predischarge symptom-limited exercise testing and 39 of them underwent exercise th allium-201 imaging, on average 3 days after the exercise test. Exercis e echocardiography was performed in 36 of these patients in conjunctio n with the predischarge exercise test. Patients with previous myocardi al infarction, coronary revascularization, left bundle branch block an d dilated cardiomyopathy were not included in the study. An echocardio graphic wall-motion score index was derived by analyzing left ventricu lar regional wall motion. During a follow-up period of 30 +/- 6.4 mont hs, 3 patients had a non-fatal myocardial infarction and 20 required r evascularization because of a recurrence of severe medically refractor y angina. Univariate predictors of cardiac events (non-fatal myocardia l infarction or a need for revascularization) during follow-up include d ST-depression during exercise, positive exercise echocardiography, a low exercise wall-motion score index, the presence of thallium-201 re distribution and the number of myocardial segments with thallium-201 r edistribution. However, stepwise logistic regression analysis revealed that the presence of thallium-201 redistribution was the only signifi cant non-invasive predictor (P < 0.005) of a cardiac event among patie nts who underwent predischarge exercise testing and exercise thallium- 201 imaging. Among patients undergoing exercise echocardiography and e xercise thallium-201 imaging, the number of segments with thallium-201 redistribution was the only significant predictor (P < 0.0005) of fut ure cardiac events. Thus, exercise thallium-201 imaging can be used to identify groups at high and low risk for future cardiac events among patients with unstable angina who respond to medical treatment.