Comparison of diabetes to other prognostic predictors among patients referred for cardiac stress testing: A contemporary analysis from the REFINE SPECT Registry

BACKGROUND: Diabetes mellitus (DM) is increasingly prevalent among contemporary populations referred for cardiac stress testing, but its potency as a predictor for major adverse cardiovascular events (MACE) versus other clinical variables is not well delineated. METHODS & RESULTS: From 19,658 patients underwent SPECT-MPI, we identified 3,122 diabetic patients without known coronary artery disease (CAD) (DM+/CAD−) and 3,564 nondiabetics with known CAD (DM−/CAD+). Propensity score matching was used to control for the differences in characteristics between DM+/CAD− and DM−/CAD+ groups. There was comparable MACE in the matched DM+/CAD− and DM−/CAD+ groups (HR:1.15, 95%CI: 0.97–1.37). By Chi-square analysis, type of stress (exercise or pharmacologic), total perfusion deficit (TPD), and left ventricular function were the most potent predictors of MACE, followed by CAD and diabetes status. The combined consideration of mode of stress, TPD, and diabetes provided synergistic stratification, an 8.87-fold (HR:8.87, 95%CI: 7.27–10.82) increase in MACE among pharmacologically stressed patients with diabetes and TPD>10% (versus non-ischemic, exercised stressed patients without diabetes). CONCLUSIONS: Propensity-matched patients with diabetes and no known CAD have similar MACE risk compared to patients with known CAD and no diabetes. Diabetes is synergistic with mode of stress testing and TPD in predicting the risk of cardiac stress test patients.