Prognostic significance of exercise thallium-201 testing in patients aged ≥70 years with known or suspected coronary artery

The prognostic value of exercise thallium-201 myocardial perfusion imaging has not been studied in an elderly (aged ≥70 years) population. Retrospective analysis of 120 consecutive elderly patients undergoing Bruce protocol exercise stress with quantitative planar thallium-201 scintigraphy, followed clinically for a mean of 36 ± 12 months after testing, revealed a 10% cardiac event rate (6 cardiac deaths from arrhythmia or congestive heart failure, and 5 fatal and 1 nonfatal myocardial infarction). There were no exercise stress-related complications. Survival without cardiac events was associated with greater exercise duration (5.6 ± 2.4 vs 3.1 ± 2.4 minutes; p < 0.0007) and peak exercise heart rate (131 ± 18 vs 120 ± 19 beats/min; p < 0.05). Univariate variables associated with higher cardiac event rates included: (1) peak exercise ≤ stage I (18 vs 6%; p = 0.04); (2) maximal ST-segment depression ≥2 mm (27 vs 6%; p = 0.003); and (3) presence of a fixed or reversible thallium-201 perfusion defect (18 vs 2%; p = 0.004). Multivariate stepwise logistic regression analysis identified the combination of peak exercise ≤ stage I and any thallium-201 perfusion defect as the most powerful predictor of subsequent cardiac events (relative risk = 5.3 at 1 year). Thus, exercise thallium-201 scintigraphy in elderly patients is safe and provides important prognostic information. Based on the peak Bruce protocol exercise stage achieved and presence or absence of a thallium-201 perfusion defect, most elderly patients (64%) can be stratified into very low- and high-risk groups with annual cardiac events rates of < 1 and > 15%, respectively.