title: Cystatin C: a potential biomarker for pulmonary arterial hypertension.
abstract: 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.
authors.affiliation: Division of Cardiology, National Jewish Health, Denver, Colorado, USA.
authors.forename: Brett E
authors.initials: BE
authors.lastname: Fenster
authors.forename: Luis
authors.initials: L
authors.lastname: Lasalvia
authors.forename: Joyce D
authors.initials: JD
authors.lastname: Schroeder
authors.forename: Jamey
authors.initials: J
authors.lastname: Smyser
authors.forename: Lori J
authors.initials: LJ
authors.lastname: Silveira
authors.forename: J Kern
authors.initials: JK
authors.lastname: Buckner
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Brown
mesh_terms: D015415:Biomarkers / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D010865:Pilot Projects; D011652:Pulmonary Circulation; D015203:Reproducibility of Results; D013223:Statistics as Topic; D013318:Stroke Volume; D016278:Ventricular Function, Right
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain
keywords: brain natriuretic peptide; cystatin C; echocardiography; pulmonary arterial hypertension; right ventricle