Prognostic value of cystatin C in acute coronary syndromes: enhancer of atherosclerosis and promising therapeutic target

Background: Cystatin C (CC) has been proposed to play a role in atherosclerosis. We aimed to review the prognostic value of CC serum/plasma levels in patients with acute coronary syndromes (ACS). Methods: Fifteen observational longitudinal studies were selected by Medline. Results: Increased CC over threshold values ranging from 0.93 to 1.3 mg/L were prognostic for death (hazard ratio; HR: 2.04-3.6) and for the occurrence of any fatal and non-fatal cardiovascular events (HR: 1.7-9.6) for patients with either ACS only or coronary heart disease and prevalent ACS. Only one study showed an increased risk for future myocardial infarction (MI) in patients with marker levels higher than 1.0 mg/L. Three studies reported the risk associated with a change of one unit of CC for long-term death (HR ranging from 1.9 to 6.3) and for the composite end point of 1 year MI and death (HR 2.15). Some studies showed the additional prognostic value contributed from CC measurements to other markers and to conventional risk scores. Conclusion: Despite low to moderate evidence, there is a general agreement on the significant prognostic value of CC in ACS that might encourage further research focused on risk assessment for patients with MI.