Time course changes of cystatin C and inflammatory and biochemical markers in non-ST-elevation acute coronary syndromes.

Background: Serum cystatin C (Cys-C), a good marker of renal function, predicts prognosis in non-ST-elevation acute coronary syndromes (NSTE-ACS). However, no data are available on the time course of Cys-C values after discharge. In this study, Cys-C was measured during admission (ACS sample) and 6 weeks after discharge, and was correlated with troponin (c-TNT), high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6) and the N-terminal portion of the pro-brain natriuretic peptide (proBNP) peptide (NT-proBNP) in a highly selected homogeneous group of NSTE-ACS patients.
Methods: In this prospective, multicentre study, patients with a first NSTE-ACS, single-vessel disease and successful percutaneous coronary interventions (PCIs) had their sera collected, aliquoted and stored at the enrolling site and then shipped for analysis to the clinical chemistry core laboratory.
Results: Cys-C values slightly, but significantly, increased from the ACS samples to the 6-week samples. In contrast, hsCRP, NT-proBNP and IL-6 values significantly decreased from the ACS to the 6-week sample. Patients with elevated c-TNT levels had higher hsCRP, NT-proBNP and IL-6 values than patients with normal c-TNT levels in the ACS sample, whereas Cys-C levels were similar in patients with and without elevated c-TNT. Cys-C was highly correlated with estimated glomerular filtration rate in both the ACS and 6-week samples.
Conclusions: In contrast to inflammatory and biochemical stress markers, Cys-C is not affected by the occurrence of myocardial necrosis or by acute left-ventricular impairment, being a reliable marker of renal function during NSTE-ACS.