Abstract 13540: Non-Invasive Quantitative Assessment of Coronary Flow Reserve Improves Cardiac Risk Assessment in Patients with Diabetes
Objectives: To evaluate the incremental prognostic value of quantitative coronary flow reserve (CFR) measured by positron emission tomography (PET) in patients with diabetes and known or suspected coronary artery disease (CAD).
Methods: 1148 consecutive patients with diabetes referred for rest/stress Rb-82 PET were followed for a median of 1.4 years (IQR: 0.7-2.4). The extent and severity of PET perfusion abnormalities was assessed by semi-quantitative visual analysis. Rest and stress myocardial blood flows (MBF) were calculated using factor analysis and a 2-compartment kinetic model, and were used to compute CFR (stress/rest MBF). Cardiac mortality was ascertained using the Social Security and National Death Indices and medical records.
Results: 76 patients died from cardiac causes (6.6%). Patients with normal, mild-moderate, and severely abnormal PET scans based on semi-quantitative visual analysis showed a stepwise increase in the annualized cardiac mortality rates (1.5, 3.9 and 8.4%, respectively; p<0.0001). After adjustment for age, sex, hypertension, dyslipidemia, family history of CAD, tobacco use, known CAD, chest pain, dyspnea, HbA1c, resting left ventricular ejection fraction (LVEF) and its change during stress, reduced CFR (below median value) correlated with increased mortality (HR 3.21 for CFR <=1.7 vs >1.7, p=0.001). Cox proportional hazards analysis revealed that global CFR added incremental prognostic value beyond clinical and PET variables (incremental chi-sq=21.6, p<0.0001; c-index 0.82 vs 0.80, p=0.04; NRI=16.4%, 95% CI 9.6-25.0%). Annualized cardiac mortality rates among patients with normal PET scans were 3.0 and 0.4% for CFR <=1.7 and >1.7, respectively (p=0.007; Figure 1).
Conclusions: Addition of quantitative CFR enables identification of extremely low risk cohorts among patients with diabetes and provides incremental risk stratification over clinical variables, semi-quantitative measures of ischemia/scar and LVEF.
- © 2011 by American Heart Association, Inc.