Cystatin C : A potential biomarker for pulmonary arterial hypertension

Background and Objective Cystatin C ( CysC ), a novel marker of renal function, predicts left heart failure and cardiovascular mortality. The hypothesis that serum CysC levels correlate with right ventricular ( RV ) morphology, function and pressure in pulmonary arterial hypertension ( PAH ) was tested. Methods As part of a prospective study, 14 PAH subjects and 10 matched controls underwent same‐day echocardiography, cardiac magnetic resonance imaging ( CMR ), and phlebotomy for CysC , brain natriuretic peptide ( BNP ), and N ‐terminal BNP ( NT ‐ ProBNP ). RV ejection fraction ( RVEF ), end‐diastolic volume, end‐systolic volume and mass were calculated using CMR . RV systolic pressure ( RVSP ), strain and diastolic function (including tricuspid valve ( TV ) E velocity, A velocity, e′ velocity, E/A ratio and E /e′ ratio) were assessed using echocardiography. Results RVSP was significantly elevated in PAH subjects versus controls (57 ± 17 vs. 28 ± 8 mm Hg, P < 0.0001). CysC was abnormally elevated in the PAH cohort when compared with controls (1.00 ± 0.23 vs 0.78 ± 0.05 mg/L, P  = 0.001). CysC positively correlated with RVSP (rho 0.61, P  = 0.002), RV end‐diastolic volume (rho 0.50, P  = 0.01), RV end‐systolic volume (rho 0.58, P  = 0.003), mass index (rho 0.66, P  = 0.0004), strain (rho 0.51, P  = 0.01) and strain rate (rho 0.51, P  = 0.01) and negatively correlated with RVEF (rho −0.58, P  = 0.003) and TV e′ (rho −0.75, P  < 0.0001). The same correlations with BNP and NT ‐ ProBNP were comparable with CysC . Conclusions In a small cohort, CysC accurately correlates with RV pressure, function and morphology. CysC may represent a novel PAH biomarker.