In BAV, circulating TGFβ1/endoglin has been shown to be upregulated (12, 13), while in RHV, TGFβ1 levels are raised in endothelial cells and SM cells of the vessels, in the perivascular interstitial cells and stroma of the valves as well as α-SMA positive cells in fibrotic areas cusp tissue and in the left atrial appendage of patients in chronic atrial fibrillation (14, 15). Here, TGFB1 is linked to atrial fibrillation.