FSTL1 and persistent truncus arteriosus: Although cardiomyocyte‐specific Fst1 knockout mice (αMHCcre+/− × Fstl1flox/flox) showed a significant decrease (~50%) of Fstl1 in the TAC model (Shimano et al, 2011), there was no appreciable attenuation of Fstl1 protein overexpression in MI model (Fig EV1A).