Long-Term Prognostic Value of Tc-99m Tetrofosmin Myocardial Gated-SPECT Imaging in Asymptomatic Patients After Percutaneous Coronary Intervention

Abstract

To evaluate the long-term prognostic value of Tc-99m tetrofosmin myocardial gated-SPECT in asymptomatic patients after coronary artery stenting. We included 246 consecutive patients in the study. All patients underwent exercise gated-single photon emission computed tomography (SPECT) myocardial imaging 5 to 7 months after percutaneous coronary intervention (PCI) and were followed for a mean period of 8.3 years (SD = 2.9). Myocardial scintigrams were evaluated calculating the summed stress score (SSS), summed rest score, and summed difference score (SDS) indexes. Cardiovascular death and nonfatal myocardial infarction were considered hard cardiac events, whereas late revascularization (>3 months after myocardial SPECT) procedures were considered to be soft events. Cox proportional hazard models were applied to evaluate the association between several variables and the investigated outcome. During the follow-up period, hard cardiac events occurred in 32 (13%) patients (cardiac death occurred in 12 patients and nonfatal myocardial infarction in 20 patients). In addition, 60 (24.4%) patients underwent a late revascularization procedure. When multiple Cox regression analysis was implied, the factors that remained significant in the final model for soft events were SSS, SDS, and angina during exercise testing. In addition, SSS, SDS, and left ventricular dilatation were independently associated with hard cardiac events as defined from the results of multiple analysis. However, SSS and SDS were the only independent predictors for both hard and soft events. Tc-99m tetrofosmin myocardial perfusion imaging (MPI), performed 6 months post-percutaneous coronary intervention, has an independent and powerful clinical value to predict hard and soft cardiac events in asymptomatic patients after PCI.