YKL-40, a Novel Marker of Cardiovascular Complications, Is Related to Kidney Function in Heart Transplant Recipients

BackgroundYKL-40 is an inflammatory glycoprotein involved in endothelial dysfunction and expressed in macrophages in the earliest lesions of atherosclerosis. Elevated serum YKL-40 levels are independently associated with the presence and extent of coronary artery disease and cardiovascular mortality. Because there are no data on heart transplant recipients and because they are prone to cardiovascular complications, the aim of this study was to assess YKL-40 in this population with particular attention to its relationship with endothelial damage. We studied 84 patients after heart transplantation. Healthy volunteers served as control subjects.MethodsComplete blood count, urea, creatinine, lipids, fasting glucose, N-terminal pro–B-type natriuretic peptide (NT-proBNP), and iron status were studied with the use of standard laboratory methods. We assessed YKL-40, copeptin, markers of inflammation high sensitivity C-reactive protein (hsCRP) and interleukin (IL) 6, and markers of endothelial cell injury von Willebrand factor (vWF) and midkine with the use of commercially available assays.ResultsMean levels of YKL-40, IL-6, vWF, and hsCRP were significantly higher in heart allograft recipients than in the control group (P < .001). In univariate analysis, YKL-40 was related to kidney function (creatinine, r = 0.63 [P < .001]; estimated glomerular filtration rate, r = −0.44 [P < .001]), NT-proBNP (r = 0.45; P < .001), age (r = 0.33; P < .01), time after transplantation (r = 0.23; P < .05), copeptin (r = −0.42; P < .001), soluble transferrin receptor (r = 0.24; P < .05), hemoglobin (r = −0.42; P < .001), transferrin (r = −0.31; P < .01), haptoglobin (r = 0.39; P < .001), cystatin C (r = 0.55; P < .001), ejection fraction (r = −0.28; P < .05), New York Heart Association functional class (r = −0.41; P < .01), hsCRP (r = 0.26; P < .05), IL-6 (r = 0.23; P < .05), vWF (r = −0.40; P < .001), and midkine (r = 0.33; P < .01). In multivariate analysis, only creatinine was found to be a predictor of YKL-40 (β = 0.59; P = .02), explaining 56% of the variation in YKL-40 levels in heart allograft recipients.ConclusionsYKL-40 may contribute to the enhanced risk of cardiovascular complications mainly owing to impaired renal function in patients after heart transplantation.