Cardiac fibrosis is associated to heart failure and poor prognosis. Cardiac fibrosis biomarkers have not been evaluated to predict cardiac resynchronization therapy (CRT) response.

Patient included according to CRT European guidelines underwent before CRT implantation clinical examination, functional test, electrocardiogram, echocardiography and blood fibrosis biomarkers evaluation. At six months, positive response to CRT was defined with a composite endpoint: no death, nor hospitalization for a cardiac cause, and presence of a left ventricular (LV) reverse remodelling (decrease in LV end-systolic volume≥15%).

A total of 60 patients were consecutively included in a multicenter study. At 6 months, 38 were positive responders to CRT and reach the composite response criteria (63%). In the CRT responders group compared to non-responders, we observed a longer QRS duration (171±22 ms vs 150±21 ms, P<0.001), more left-bundle branch block (LBBB) (58% vs 25%, P<0.001), non-ischemic cardiomyopathy (75% vs 30%, P=0.02), and a lower fibrosis biomarker concentration procollagen type I C-terminal propeptide (PICP [139±53ng/ml vs 93±87ng/ml, P=0.005]). PICP was inversely correlated to LV reverse remodelling (r²=0.38, P=0.005) and was significantly higher in CRT non-responders patients despite a LBBB (268±158ng/ml vs 129±53ng/ml, P<0.001) or a non-ischemic cardiomyopathy (232±90ng/ml vs 142±57ng/ml, P<0.001). In multivariate analysis, a PICP≤163ng/ml was associated to CRT response [OR=15 (2.3–106), P=0.03] (Fig. 1).

A lower degree of cardiac fibrosis is associated to positive response after CRT implantation. PICP evaluation before CRT implantation may improve patient selection usually only based on electrical asynchronism and LV function.