Aims: We investigated whether collagen type I turnover influences the long-term response to cardiac resynchronization therapy (CRT).
Methods and 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).
Conclusion: 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.