Abstract 11917: Synergy Between Coronary Risk Factor Burden and Testing Mode Produce a Marked Heterogeneity in Long-Term Mortality Rates Following Normal Stress Myocardial Perfusion SPECT
Background: Whereas a normal stress SPECT study is generally associated with excellent short term prognosis, both the mode of stress testing and CAD risk factors (RFs) can influence the trajectory of long-term outcomes. Nevertheless, the combined impact of these routinely assessed factors has not heretofore been considered.
Methods: We assessed all cause mortality rates among 5,619 patients (60 ± 13 yrs, 36% male) with no known CAD and a normal stress SPECT. Patients were divided according to stress mode: - exercise (EX) vs. dipyridimole (DIPY) - and according to baseline CAD risk factors (RFs). Patients were followed for a mean of 8 ± 4 years with mortality assessed using SSDI.
Results: There were 930 deaths (17%) among this patient cohort with an event rate of 2.1%/yr. RF- adjusted event rate was significantly higher both for DIPY versus EX SPECT (3.3%/ Vs. 1.3%/yr p<0.0001), as well as for patients with increasing number of CAD risk factors: 1.1 % for 0 RFs, 1.9%/yr for 1 RF, and 2.9%/yr, for ≥ 2 RFs (p< 0.0001). Kaplan-Meier survival analysis revealed a wide heterogeneity in outcomes when both RF burden and performance of EX versus DIPY testing were considered together (Figure). The annualized mortality rate increased more than four-fold from EX patients with no RFs (0.8%/yr) to DIPY patients with ≥ 2 RFs (3.8%/yr). Interestingly, mortality rates in EX patients with ≥ 2 RFs were comparable to DIPY patients with 0 RF.
Conclusion: Long-term outcomes following a normal stress SPECT study is highly and synergistically influenced by both RF burden and mode of stress testing. Thus, combined consideration of these factors can improve risk characterization following a normal stress SPECT study, with the potential of leading to improved patient counseling and physician management.
- © 2011 by American Heart Association, Inc.