Sirius red staining for collagen abundance presented significant higher levels of interstitial (but not subepicardial) fibrosis in PKP2-Hz TAC mice compared with sham-treated WT and PKP2-Hz mice (WT-Sham: 1.64% ± 0.1%; WT-TAC 2.83% ± 0.95%; PKP2-Hz Sham: 1.86% ± 0.29%; and PKP2-Hz TAC: 5.0% ± 0.86%, p ≤ 0.05 vs. WT-Sham and PKP2-Hz Sham; Figure 4G,H). Here, PKP2 is linked to persistent truncus arteriosus.