LAUSR

Diabetes mellitus (DM) is an expanding global epidemic. Estimates of a global prevalence of 415 million people and total health expenditure of 673 billion US dollars have been reported. The prevalence of individuals between 20 and 79 years with diabetes is predicted to rise to 642 million by 2040. Assessment of morbid risk of diabetes is of substantial importance in the allocation of resources to address the human and financial burdens of this growing global health threat. Epidemiological studies have demonstrated that diabetes places patients at an elevated risk for developing coronary artery disease (CAD). A large meta-analysis of 102 studies confirmed a two-fold excess risk for vascular disease in DM. Since the landmark study by Haffner first reported the equivalence of risk of diabetes and CAD, widespread controversy has ensued with several studies, which have supported or challenged the concept of risk equivalent of DM and CAD. The substantial incremental risk assessment of radionuclide SPECT MPI compared to the exercise ECG and echocardiography reported in referred populations suggests its role to refine the heterogeneity of risk in patient populations with CAD and/or DM. The DIAD study reported that 22% of asymptomatic diabetic patients had myocardial ischemia on adenosine Tc-99 m SPECT MPI, and subsequent COURAGE, INSPIRE, and BARI-2D trials confirmed the powerful incremental risk assessment with SPECT MPI as well as favorable effects of optimal medical therapy in patients with CAD and/or DM. In the current issue of the Journal of Nuclear Cardiology, Morales et al. report a large retrospective analysis of 17,499 patients undergoing SPECT MPI at a single tertiary center from 1996 to 2006. The study explores the interaction of risks of subsequent hard coronary events identified by diabetes mellitus, history of CAD, and the presence of greater than mild stress perfusion defect (SSS C 4) equivalent to a 6% total stress LV perfusion defect score. Patients were divided into four groups based on CAD and DM status at the time of initial imaging: non-DM patients without CAD (N = 9133), non-DM patients with CAD (N = 3906), DM patients without CAD (N = 2768), and DM patients with CAD (N = 1692). These four groups were further divided based on summed stress score (SSS)\ 4 or C 4 to classify normal and abnormal perfusion, respectively. Yearly event rate for the composite end point of cardiac death or non-fatal myocardial infarction (MI) was calculated over a mean follow-up of 2.4 ± 1.5 years with a maximum of 5 years. As expected, SPECT MPI did contribute incremental risk assessment to patients with CAD and/or DM. Although the rates of events in patients with diabetes without CAD and those with CAD without diabetes were similar by inter-group comparison, robust Reprint requests: Ronald G. Schwartz, MD, MS, Department of Medicine, Cardiology Division, University of Rochester Medical Center, Box 679-N, 601 Elmwood Avenue, Rochester, NY 14642; [email protected] J Nucl Cardiol 2019;26:1103–6. 1071-3581/$34.00 Copyright 2018 American Society of Nuclear Cardiology.