EDN1 and atrial fibrillation: AF-dependent negative changes in the microcirculation (Goette et al., 2009; Bukowska et al., 2012) contribute to and further enhance increased gene expression and release of ET-1 which, in turn, aggravates coronary vasoconstriction (Neubauer et al., 1991; Hiller et al., 1997) and leads to oxidative stress (Nagase et al., 1990).