Diagnostic Methods Thallium Exercise Testing

The goal of this study was to determine the prognostic utility of the exercise thallium201 stress test in ambulatory patients with chest pain who were also referred for cardiac catheterization. Accordingly, 4 to 8 year (mean ± 1SD, 4.6 + 2.6 years) follow-up data were obtained for all but one of 383 patients who underwent both exercise thallium-201 stress testing and cardiac catheterization from 1978 to 1981. Eighty-three patients had a revascularization procedure performed within 3 months of testing and were excluded from analysis. Of the remaining 299 patients, 210 had no events and 89 had events (41 deaths, nine nonfatal myocardial infarctions, and 39 revascularization procedures . 3 months after testing). When all clinical, exercise, thallium-201, and catheterization variables were analyzed by Cox regression analysis, the number of diseased vessels (when defined as > 50% luminal diameter narrowing) was the single most important predictor of future cardiac events (X2 = 38.1) followed by the number of segments demonstrating redistribution on delayed thallium-201 images (X2 = 16.3), except in the case of nonfatal myocardial infarction, for which redistribution was the most important predictor of future events. When coronary artery disease was defined as 70% or greater luminal diameter narrowing, the number of diseased vessels significantly (p <.01) lost its power to predict events (X2 = 14.5). Other variables found to independently predict future events included change in heart rate from rest to exercise (x2 = 13.0), ST segment depression on exercise (X2 = 13.0), occurrence of ventricular arrhythmias on exercise (X2 = 5.9), and 6-blocker therapy (X2 = 4.3). The exclusion of myocardial revascularization procedures as an event did not change the results significantly. Although the number of diseased vessels was the single most important determinant of future events, the exercise thallium-201 stress test when considered as a whole (which included the number of segments demonstrating redistribution on delayed thallium-201 images, change in heart rate from rest to exercise, ST segment depression on the electrocardiogram, and ventricular premature beats on exercise) was equally powerful (X2 = 41.6). Combination of both catheterization and exercise thallium-201 data was superior to either alone (X2 = 57.5) for determining future events. Exercise stress test alone (without thallium-201 data) was inferior to the exercise thallium-201 stress test or cardiac catheterization for predicting future events (X2 = 30.6). Thus the exercise thallium-201 stress test provides important prognostic information in ambulatory patients presenting with chest pain. When cardiac catheterization findings are known, exercise thallium-201 stress test data are additive in identifying patients at high risk for subsequent events. Circulation 77, No. 4, 745-758, 1988. From the Divison of Cardiology, Department of Internal Medicine, CORONARY ARTERY DISEASE (CAD) is the most University of Virginia School of Medicine, Charlottesville. Supported in part by Clinical Investigator Award K08-HL01833 (Dr. common cause of mortality and morbidity in the westKaul) and by Research Grant R01-HL26205 from the NHLBI. ern hemisphere.' Although new mechanisms for the Address for correspondence: Sanjiv Kaul, M.D., Divison of Cardiology (Box 158), University of Virginia, Charlottesville, VA 22908. genesis of acute myocardial infarction, unstable angina Received Oct. 20, 1987; revision accepted Jan. 14, 1988. pectoris, and sudden death are now being identified, Presented in part at the 58th Annual Scientific Sessions of the Amert s a i ican Heart Association, Dallas, November 1985. these sndromes almost invariablv occur in the settin *Current address: Milton S. Hershey Medical Center, Pennsylvania of significant CAD.24 Therefore it is not surprising State University, Division of Cardiology, Box 850, Hershey, PA 17033. that the occurrence of such events has, in the past, been **Current address: Ohio State University, Division of Cardiology, crat the e xte of c aD. i he nat all 1654 Upman Dr., Columbus, OH 43210. correlated with the extent of CAD. However, not all Vol. 77, No. 4, April 1988 745 by gest on A ril 3, 2017 http://ciajournals.org/ D ow nladed from