P4157Coronary flow reserve but not ischemia is a strong predictor of mortality in 551 outpatients referred for stress myocardial perfusion by Rubidium-82 PET imaging

Background The assessment of myocardial ischemia in patients with suspected coronary artery disease (CAD) is encouraged by current guidelines. The ischemic burden is associated with impaired prognosis. Coronary flow reserve (CFR) is also an independent predictor of cardiovascular mortality but it is unclear which one of these two variables would be stronger to predict mortality. Purpose To evaluate the predictors of death in symptomatic stable patients with suspected CAD referred for stress myocardial perfusion (MP) Rubidium-82 PET imaging. Methods 551 consecutive patients (52% men, mean age 63 years) were enrolled in this study from February to October 2013. The primary endpoint was all-cause death. The event-free survival curves for the primary endpoint were obtained using the Kaplan-Meier method in four groups of patients based on whether ischemia was present and whether CRF was impaired (<2) (Figure). Univariate analysis was performed using Cox regression to identify the variables that were associated with mortality, and the Cox proportional-hazards regression model for the multivariate analysis adjustment. Results During a median follow-up period of 32 months there were 43 deaths giving an estimated cumulative event rate of 7.8%. Univariate predictors of death were: age, higher prevalence of DM and CKD, lower LVEF and BMI. Following a multivariate analysis, only CFR was independently associated with mortality (Table). Predictors of death Variable Univariate model Multivariate model HR (95% CI) P value HR (95% CI) P value Age 1.03 (1.00–1.06) 0.036 1.01 (0.99–1.04) 0.324 Male sex 1.41 (0.76–2.56) 0.277 0.96 (0.70–1.32) 0.809 History of DM 2.12 (1,13–3,97) 0.019 – – History of CKD 4.95 (2,66–9,20) <0.001 – – BMI <30 1.14 (1.05–1.22) <0.001 2.22 (0.93–5.26) 0.071 Rest LVEF, % 0.98 (0.96–0.99) 0.029 0.99 (0.98–1.01) 0.477 Ischemia, % 1.02 (0.97–1.06) 0.436 0.99 (0.91–1.10) 0.990 Ischemia ≥10% 1.33 (0.59–2.99) 0.488 0.90 (0.40–2.05) 0.806 CFR 0.26 (0.15–0.43) <0.001 0.27 (0.16–0.46) <0.001 LVEF = left ventricular ejection fraction. Survival curves for all-cause death. Conclusions In symptomatic outpatients with suspected CAD referred for stress MP Rubidium-82 PET imaging, CFR is the strongest predictor of mortality. Notably, neither the presence of ischemia nor the ischemic burden was associated with the outcome in question.