title: Procollagen propeptides: serum markers for atrial fibrosis?
abstract: BACKGROUND
  Atrial fibrosis and its spatial heterogeneity are regarded as a substrate for the perpetuation of atrial arrhythmias. During collagen synthesis and degradation, collagen propeptides and telopeptides are released into the blood. This study tested the hypothesis that serum markers of collagen turnover correlate with atrial fibrosis.
  
  
  METHODS
  We prospectively included 28 patients in sinus rhythm undergoing cardiac surgery. Plasma concentrations of the carboxy- and amino-terminal propeptide of procollagen type-I (PICP and PINP) and type-III (PIIINP), and the C-terminal telopeptide of type-I collagen (ICTP) were determined. Interstitial fibrosis of left (n = 10) and right atrial appendages (n = 28) was analyzed histologically.
  
  
  RESULTS
  We found a correlation between left and right atrial fibrosis (r (s) = 0.79, p < 0.01). Interestingly, the higher the interstitial collagen content, the higher was the spatial heterogeneity of fibrosis (r (s) = 0.90, p < 0.001). However, PICP, PIIINP, and ICTP were not correlated to left or right atrial collagen content, or to the spatial heterogeneity of atrial fibrosis. There was a weak and even negative correlation between the serum PINP concentration and the degree of fibrosis in both the left and the right atrium (r (s) = -0.65 (p = 0.04) and r (s) = -0.42 (p = 0.03), respectively).
  
  
  CONCLUSIONS
  A high degree of interstitial atrial fibrosis indicates a high degree of spatial heterogeneity of interstitial collagen. Although serum PICP is known to be correlated with ventricular fibrosis, this and other serum markers of collagen turnover (PINP, PIIINP, and ICTP) do not directly reflect atrial fibrosis in patients with severe cardiac disease.
authors.affiliation: Klinik für Innere Medizin III, Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, 66421 Homburg/Saar, Germany. hr.neuberger@t-online.de
authors.forename: Hans-Ruprecht
authors.initials: HR
authors.lastname: Neuberger
authors.forename: Angela
authors.initials: A
authors.lastname: Cacciatore
authors.forename: Jan-Christian
authors.initials: JC
authors.lastname: Reil
authors.forename: Stefan
authors.initials: S
authors.lastname: Gräber
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Schäfers
authors.forename: Christian
authors.initials: C
authors.lastname: Ukena
authors.forename: Michael
authors.initials: M
authors.lastname: Böhm
authors.forename: Christian
authors.initials: C
authors.lastname: Mewis
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D005260:Female; D005355:Fibrosis; D006325:Heart Atria / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000097:blood*; D011347:Procollagen / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; D011347:Procollagen