Markers of an intense scarring process in the early phase post- myocardial infarction (MI) are still undetermined, and the identification of patients at higher risk of developing large adverse fibrotic remodeling and heart failure remains challenging. Here, the inventors demonstrate the modulation in the paracrine behavior of resident PW1+ cells in scarring cardiac tissue post-MI and the differential abundance of 12 candidate markers in their secretome. Of these, growth differentiation factor 3 (GDF3), a member of transforming growth factor-? family, upregulates proliferation of cardiac fibroblasts, which are instrumental in fibrosis. GDF3 is upregulated in the scarred tissue and plasma of mice and humans post-MI, with the highest plasma levels predicting higher fibrotic cardiac remodeling and cardiac dilation. The inventors thus reveal the previously unidentified function of GDF3 in predicting adverse fibrotic cardiac remodeling post-MI. Thus the present invention relates to the use of GDF3 as biomarker and biotarget in post-ischemic cardiac remodeling.