Influence of Mode of Stress and Coronary Risk Factor Burden Upon Long-Term Mortality Following Normal Stress Myocardial Perfusion Single-Photon Emission Computed Tomographic Imaging

In patients with normal results on stress single-photon emission computed tomographic (SPECT) studies, coronary artery disease risk factors (RFs) and the mode of testing can influence the trajectory of long-term outcomes. Nevertheless, the combined prognostic impact of these commonly assessed factors has heretofore not been considered. In this study, all-cause mortality rates were assessed in 5,762 patients with normal results on stress SPECT studies. Patients were divided according to mode of stress testing, exercise or pharmacologic, and by number of coronary artery disease RFs. Patients were followed for a mean of 8 ± 4.2 years for all-cause mortality. There were 1,051 deaths (18%), with an annualized mortality rate of 2.2% per year. The RF-adjusted event rate was significantly higher for pharmacologic versus exercise SPECT studies (3.6% per year vs 1.2% per year, p <0.0001) and for patients with increasing numbers of coronary artery disease RFs (p <0.0001). Kaplan-Meier survival analysis revealed wide heterogeneity in all-cause mortality rates when RF burden and performance of exercise versus pharmacologic testing were considered, ranging from only 0.8% per year in exercise patients with no RFs to 4.2% per year in pharmacologic patients with ≥2 RFs. Mortality rates in exercise patients with ≥2 RFs were comparable to those in pharmacologic patients with no RFs. In conclusion, long-term outcomes after cardiac stress testing are synergistically and strongly influenced by RF burden and inability to exercise. Given these findings, prospective study is indicated to determine whether enhanced risk categorization that combines the consideration of these 2 factors improves patient counseling and physician risk management among patients manifesting normal results on stress SPECT studies.