Metabolic Syndrome and Diabetes Are Associated With an Increased Likelihood of Inducible Myocardial Ischemia Among Patients With Subclinical Atherosclerosis

Abstract

Coronary artery calcification (CAC) is associated with cardiac events and the likelihood of inducible myocardial ischemia. Because metabolic syndrome contributes to atherosclerosis, we assessed whether it also influences the relationship between CAC levels and myocardial ischemia. We evaluated 1,043 patients without known coronary artery disease (CAD) who underwent stress myocardial perfusion scintigraphy (MPS) and computed tomography. Metabolic syndrome was defined by modified National Cholesterol Education Program criteria. Metabolic abnormalities were present in 313 patients (30%), including 140 with diabetes (with or without metabolic syndrome) and 173 who had metabolic syndrome without diabetes. Although CAC scores <100 identified a low likelihood ( approximately 2%) of ischemia, the presence (versus absence) of metabolic abnormalities (metabolic syndrome or diabetes) was a predictor of more frequent ischemia among patients with CAC scores of 100-399 (13.0 vs. 3.6%, P < 0.02) and CAC scores >/=400 (23.4 vs. 13.6%, P = 0.03). Similar trends were observed when patients with metabolic syndrome and diabetes were considered separately. Multiple logistic regression revealed the odds of MPS ischemia to be 4.3-fold greater per SD of log CAC (P < 0.001) and 2.0-fold greater in the presence of metabolic abnormalities (P < 0.01). Among patients with CAC scores >/=100, metabolic abnormalities, and even metabolic syndrome in the absence of diabetes predicted a higher likelihood of inducible ischemia. These findings suggest the need for assessment of metabolic status when interpreting the results of CAC imaging among patients undergoing such testing because of suspected CAD.