Not my cup of tea, but you may want to look at carboxyl-terminal peptide of procollagen type I (PIP), carboxyl-terminal telopeptide of collagen type I (CITP), and amino-terminal peptide of procollagen type III (PIIINP).
In agreement with Ugur, the MMPs you might want to focus on are 2 and 9, and maybe 7 and 14. In the literature, these are all associated with cardiac fibrosis.