Metabolic syndrome attenuates effect of chronic kidney disease on prevalence of coronary disease in men referred for stress imaging study

Background: Metabolic syndrome (MS) and chronic kidney disease (CKD) are both strongly associated with coronary artery disease (CAD). Components of MS also cause CKD. The incremental effect of CKD on CAD prevalence in MS patients referred for stress imaging studies is unknown. Methods: From January to December 2005, consecutive subjects referred for a stress imaging study were prospectively enrolled. CAD was defined as fixed or reversible defects on nuclear imaging and as resting or stress-induced wall motion abnormalities on echocardiography. MS was defined using NCEP-ATP III criteria. CKD definition was based on calculated glomerular filtration rate. The independent effect of CKD on stress results was assessed using multiple variable logistic regression. Stepwise model selection was used for variable reduction, and areas under the receiver operating characteristic curves (ROC) were calculated. Results: Of 1,122 patients enrolled (mean age 61.4 years, 97% male), 535 (47%) had MS. Among MS patients, 156/535 (29%) had CKD while 116/587 (19%) subjects without MS had CKD. Subjects with CKD were older (p < 0.001) in subjects with and without MS. The presence of CKD affected prevalence of CAD in the non-MS group only, almost doubling it (20% vs. 38%, p < 0.001). Further, using the ordered nature of the 5 CKD stages, worsening severity of CKD had greater prevalence of CAD, in non-MS subjects only (p < 0.001). Conclusions: MS attenuates the effect of CKD on CAD prevalence, regardless of CKD severity. CKD almost doubles the prevalence of CAD in non-MS subjects. CKD severity is associated with greater CAD burden in the non-MS group.