COL3A1 and fibrosis: TAC mice developed pathological cardiac remodelling with left ventricular dilatation, decreased fractional shortening and increased expression of the HF markers ANP, BNP and Myh7 and cardiac fibrosis markers CTGF, Col1 and Col3a1, and developed HFrEF caused by systolic dysfunction with left ventricular dilatation (Supplementary Fig. 1a,b).