title: Impact of collagen type I turnover on the long-term response to cardiac resynchronization therapy.
abstract: OBJECTIVE
  We investigated whether collagen type I turnover influences the long-term response to cardiac resynchronization therapy (CRT).
  
  
  RESULTS
  Serum carboxy-terminal propeptide of procollagen type I or PICP (a marker of collagen type I synthesis) and carboxy-terminal telopeptide of collagen type I or CITP (a marker of collagen type I degradation) were measured in heart failure patients at baseline and after 1 year of CRT. Patients were categorized as responders or non-responders if they increased the distance walked in 6 min by > or <10%, respectively. At baseline, the PICP:CITP ratio, an index of the degree of coupling between collagen type I synthesis and degradation was higher (P = 0.006) in responders than in non-responders. Whereas the PICP:CITP ratio decreased (P= 0.000) after treatment in responders, it remained unchanged in non-responders. Thus, at 1-year, the PICP:CITP ratio was similar in the two groups of patients. A direct correlation (r = 0.289, P = 0.037) was found between the baseline PICP:CITP ratio and the change in the distance walked in 6 min in all patients. Receiver operating characteristics curves showed that a cut-off value of 14.4 for the PICP:CITP ratio provided 70% specificity and 63% sensitivity for the predicting response to CRT with a relative risk of 2.07 (95% confidence interval, 0.98-4.39).
  
  
  CONCLUSIONS
  Collagen type I turnover influences the long-term response to CRT. In addition, the ability of CRT to restore the balance between collagen type I synthesis and degradation is associated with a beneficial response.
authors.affiliation: Department of Cardiology and Cardiovascular Surgery, University Clinic, School of Medicine, University of Navarra, Pamplona, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: García-Bolao
authors.forename: Begoña
authors.initials: B
authors.lastname: López
authors.forename: Alfonso
authors.initials: A
authors.lastname: Macías
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Gavira
authors.forename: Pedro
authors.initials: P
authors.lastname: Azcárate
authors.forename: Javier
authors.initials: J
authors.lastname: Díez
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D024042:Collagen Type I / Q000378:metabolism*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology / Q000637:transplantation; D006333:Heart Failure / Q000378:metabolism / Q000628:therapy*; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000378:metabolism*; D011347:Procollagen / Q000378:metabolism*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D016138:Walking
chemical_list: D024042:Collagen Type I; D010446:Peptide Fragments; D011347:Procollagen; C042813:procollagen type I carboxy terminal peptide