Plasma cystatin C for prediction of 1-year cardiac events in Mediterranean patients with non-ST elevation acute coronary syndrome

Objective: Evaluation of renal function (RF) is important for management of patients with non-ST elevation acute coronary syndrome (NSTE-ACS). Cystatin C, a sensitive marker of RF, appears to be also a marker of cardiovascular risk. Little is known regarding its predictive role in NSTE-ACS patients. Methods: We assessed 525 patients taking part in the “Systemic Inflammation Evaluation in patients with NSTE-ACS” (SIESTA) study. Patients were subdivided in quartiles according to cystatin C plasma concentrations (mg/L), i.e., Q1 < 0.81; Q2 = 0.81–0.92; Q3 = 0.93–1.10; Q4 ≥ 1.11. Glomerular filtration rate (eGFR) was estimated using the modification of diet in renal disease (MDRD) equation. The study endpoint was the composite of cardiac death, non-fatal myocardial infarction and unstable angina at 1-year follow up. Results: Few patients (0.8%) had severely impaired RF (MDRD < 30 ml/min/1.73 m2). 157 patients reached (30%) the study end-point. Patients in Q3 and Q4 showed a higher cumulative probability of cardiac events compared to patients in the lowest quartile. On multivariable analysis, patients in Q3 and Q4 had an increased incidence of cardiac events (adjusted HR = 1.57 95%CI 1.04–2.49; p = 0.036). Patients with TIMI risk score ≥3 or in-hospital heart failure were also at higher risk for acute cardiac events. Conventional markers of RF, i.e., serum creatinine and eGRF, were not predictors for the study end-point. Conclusions: Increased levels of cystatin C were an independent predictor of cardiac events at 1-year follow up in this contemporary series of Mediterranean patients with NSTE-ACS.