Prognostic Stratification Using Dobutamine Stress ^99mTc-Tetrofosmin Myocardial Perfusion SPECT in Elderly Patients Unable to Perform Exercise Testing

Abstract

Information on the prognostic value of noninvasive stress imaging techniques in the elderly is relatively scarce. This study assessed the prognostic value of dobutamine stress ^99mTc-tetrofosmin SPECT for the prediction of mortality and cardiac events in elderly patients. Methods: Clinical information and SPECT results were analyzed for 272 consecutive patients ≥ 65 y old (mean age, 71 ± 5 y; range, 65–87 y) with limited exercise capacity. Follow-up was complete in 270 patients (99.3%); 23 underwent revascularization within 60 d of the scintigraphy and were excluded. Abnormal findings were defined as the presence of a fixed or reversible perfusion defect. A summed stress score was obtained to estimate the extent and severity of perfusion defects. The incremental prognostic value of SPECT over clinical data was evaluated according to 3 multivariate models, which included any SPECT abnormality, the presence of a fixed or reversible defect, and the summed stress score. Results: During the follow-up (3.3 ± 1.4 y), 59 patients died (29 cardiac deaths), 16 had a nonfatal infarction, and 49 underwent late revascularization. Abnormal scan findings were present for 140 patients (57%). The annual event rates for total mortality, cardiac death, and cardiac death or nonfatal infarction were, respectively, 3.2%, 0.2%, and 0.7% when scan findings were normal and, respectively, 9.5%, 4.3%, and 8% when scan findings were abnormal (all P < 0.0001). Multivariate analysis showed that abnormal scan findings, the presence of a fixed or reversible defect, and the summed stress score provided incremental prognostic information over clinical data. The presence of abnormal scan findings was independently associated with an increased risk for total mortality, cardiac death, and cardiac death or nonfatal infarction (respectively, hazard ratio 3.4 [95% CI, 1.8–6.5], 12.1 [95% CI, 2.9–51.5], and 9.0 [95% CI, 2.8–29.6]). Conclusion: Dobutamine stress ^99mTc-tetrofosmin SPECT provides incremental prognostic information for the prediction of total mortality and cardiac events in elderly patients.