P6534Prognostic implication of serum cystatin C and creatinine-based glomerular filtration rate ratio in coronary disease patients receiving PCI: a surrogate of low muscle mass and a predictor of mortality

Background Low muscle mass results in impaired exercise capacity and is related with poor prognosis in chronic diseases. Although the ratio of serum creatinine (Scr) to cystatin C (Scys) is known as a surrogate marker of body muscle mass, the value of this marker is unclear in the patients with coronary artery disease (CAD). Purpose We assessed the clinical significance of two markers representing body muscle mass, the ratio of Scr to Scys (Scr/Scys), and ratio of estimated glomerular filtration rate by Scys to Scr (eGFRcys/eGFRcr). Methods We analyzed patients enrolled in a single tertiary center prospective percutaneous coronary intervention (PCI) registry that had Scr and Scys levels simultaneously measured before PCI. Optimal cut-off values of Scr/Scys and eGFRcys/eGFRcr, and their prognostic impact on 3-year mortality after PCI were analyzed. Subgroup analysis according to various demographics and risk factors was performed. Results A total of 1,928 patients who underwent PCI for significant CAD were analyzed (age 65.2±9.9 years, 70.8% men). Both Scr/Scys and eGFRcys/eGFRcr showed strong correlation with estimated proportion of muscle mass. Cut-off values of Scr/Scys discriminating 3-year death were 1.0 for men and 0.8 for women, while those of eGFRcys/eGFRcr were 1.1 for men and 1.0 for women. Both Scr/Scys- and eGFRcys/eGFRcr-based low muscle mass groups showed significantly higher risk of death, after adjusting for 7 selected covariates including age. The additional discriminative power of low muscle mass group on the predictive model was greater in the group determined by eGFRcys/eGFRcr than Scr/Scys. Low eGFRcys/eGFRcr values showed additional prognostic impact especially in patients older than 65 years, non-obese, men, chronic kidney disease, and current smokers. Conclusions Low muscle mass was an independent prognostic indicator in the patients who underwent coronary stenting. eGFRcys/eGFRcr was identified as a useful surrogate of muscle mass, which may be used to detect vulnerable patients with low muscle mass at high risk for future events. Acknowledgement/Funding None