Metabolic Syndrome Does Not Predict an Increased Risk of Coronary Disease in Patients with Traditional Risk Factors Referred for Stress Imaging Study

Background: The impact of metabolic syndrome on the prediction of coronary artery disease (CAD) in subjects with multiple traditional risk factors is unknown. Methods: We enrolled 2,626 consecutive subjects who underwent clinically indicated stress imaging studies using echocardiography or single-photon emission computed tomography (SPECT) myocardial perfusion. Patients with known CAD were excluded leaving 1256 subjects. Metabolic syndrome was defined by National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. The number of traditional risk factors and the presence of metabolic syndrome were compared with the results of stress imaging. Logistic regression analysis was used to assess the impact of metabolic syndrome on CAD prevalence in subjects with limited (≤2) traditional risk factors and multiple (≥3) risk factors. Results: Metabolic syndrome was present in 540 (43%) of subjects. Presence of metabolic syndrome was associated with a nonsignificant 3%–4% increase in overall prevalence of CAD. Metabolic syndrome did not increase the prevalence of CAD in those with multiple (≥3) traditional risk factors (metabolic syndrome 25% vs. no metabolic syndrome 21%, P = 0.62) or in those with limited (≤2) risk factors (metabolic syndrome 19% vs. no metabolic syndrome 16%, P = 0.13). The presence of multiple versus limited risk factors had poor accuracy for prediction of CAD with area under the receiver operating curve (ROC) = 0.52. Information on the presence or absence of metabolic syndrome did not improve identification of CAD, ROC area of 0.54, P = not significant (N.S.). None of the five individual components of metabolic syndrome showed significant association with CAD. Conclusions: The addition of metabolic syndrome to traditional risk factors does not increase the prevalence of CAD determined by stress imaging.