Usefulness of Stress Gated Technetium-99m Single Photon Emission Computed Tomographic Myocardial Perfusion Imaging for the Prediction of Cardiac Death in Patients With Moderate to Severe Left Ventricular Systolic Dysfunction and Suspected Coronary Artery Disease

Abstract

Although stress gated technetium-99m single-photon emission computed tomographic (SPECT) myocardial perfusion imaging (MPI) is useful in differentiating ischemic from nonischemic cardiomyopathy, its prognostic usefulness in this patient population is not well understood. Consecutive unique patients with suspected coronary artery disease who, for clinical indications, underwent technetium-99m rest and stress MPI demonstrating ejection fractions ≤40% by gated SPECT imaging were retrospectively identified. In addition to prescan variables, previously defined cutoffs for gated SPECT parameters using visual and standard 17-segment semiquantitative scoring were applied and related to the occurrence of cardiac death up to 5 years after MPI. Of the 475 patients fulfilling criteria for study inclusion, follow-up was complete in 444 (93%) over 3.7 ± 1.6 years. Of 393 patients without subsequent early (≤60 days) coronary revascularization, cardiac death occurred in 64 (16%). The summed stress score, an MPI measure of the extent and severity of coronary artery disease that also accounts for the ischemic burden, was the gated SPECT parameter most related to cardiac death with Kaplan-Meier 5-year cardiac death-free survival of 85.6% and 67.3% in patients with summed stress scores ≤8 and >8, respectively (p <0.001). In multivariate Cox regression analysis, a summed stress score >8 independently contributed to cardiac death (adjusted hazard ratio 2.20, 95% confidence interval 1.34 to 3.61), and its addition to the model significantly increased the global chi-square value over prescan variables (from 32.46 to 41.67, p = 0.002). In conclusion, stress MPI data from gated technetium-99m SPECT scans are useful for the prediction of cardiac death in patients with moderate to severe left ventricular systolic dysfunction in whom there is suspicion of underlying coronary artery disease.