Cystatin C for Risk Stratification in Patients After an Acute Coronary Syndrome

Background Cystatin C (Cys‐C) is a marker of renal function that has shown prognostic value for cardiovascular risk stratification across different patient populations. The incremental value of Cys‐C beyond established cardiac and renal biomarkers remains incompletely explored. Methods and Results SOLID‐TIMI 52 (Stabilization of Plaques Using Darapladib‐Thrombolysis in Myocardial Infarction 52; www.clinicaltrials.gov, NCT01000727) randomized patients ≤30 days post–acute coronary syndrome were treated with darapladib or placebo. The association between Cys‐C and long‐term risk (median follow‐up 2.5 years) was assessed in 4965 individuals with adjustments made for clinical variables and other risk markers (eg, estimated glomerular filtration rate, high‐sensitivity troponin I, brain‐type natriuretic peptide, and fibroblast growth factor‐23). The prespecified outcome of interest was cardiovascular death (CVD) or heart failure hospitalization. Cys‐C was strongly correlated with creatinine (r=0.60) and estimated glomerular filtration rate (r=−0.68), moderately correlated with fibroblast growth factor‐23 (r=0.39), and weakly correlated with brain‐type natriuretic peptide (r=0.28) and high‐sensitivity troponin I (r=0.06) (all P