Objectives: Reduced number and impaired function of circulating endothelial progenitor cells (EPCs) in patients with chronic kidney disease have been reported. However, there is little data about the association between circulating EPC levels and risk of contrast-induced nephropathy (CIN). The aim of this study was to investigate the relationship between circulating EPCs and CIN in patients after angiography.
Methods and results: A total of 77 consecutive patients undergoing elective percutaneous coronary intervention (PCI) and percutaneous transluminal angioplasty (PTA) were enrolled. Flow cytometry with quantification of EPC markers (defined as CD34+, CD34+KDR+, and CD34+KDR+CD133+) in peripheral blood samples was used to assess EPC number before the procedure. CIN was defined as an absolute increase ≧0.5 mg/dl or a relative increase ≧25% in the serum creatinine level at 48 hours after the procedure. Eighteen (24%) of the study subjects developed CIN. Circulating EPC levels were significantly lower in patients who developed CIN than in those without CIN (CD34+KDR+, 4.11±2.59 vs. 9.25±6.30 cells/105 events, P<0.001). The incidence of CIN was significantly greater in patients in the lowest EPC tertile (CD34+KDR+; from lowest to highest, 52%, 15%, and 4%, P<0.001). Using univariate logistic regression, circulating EPC number (CD34+KDR+) was a significant negative predictor for development of CIN (odds ratio 0.69, 95% CI 0.54-0.87, P = 0.002). Over a two-year follow-up, patients with CIN had a higher incidence of major adverse cardiovascular events including myocardial infarction, stroke, revascularization of treated vessels, and death (66.7% vs. 25.4%, P = 0.004) than did patients without CIN.
Conclusions: Decreased EPC level is associated with a greater risk of CIN, which may explain part of the pathophysiology of CIN and the poor prognosis in CIN patients.