CD4 and persistent truncus arteriosus: The studies on T cell knock-outs and transgenic (36–38) OVA specific TAC mouse model have demonstrated a clear role of CD4 T cells in heart failure (36, 37) and showed CD8 T cells does not lead to heart failure even though higher CD8 T cells were present in myocardium of OVA antigen expressing transgenic mice after TAC (38).