XAF-1407 (XAF1407) is a novel putatively potent and highly specific IK,Ach (Kir3.1/3.4 and Kir3.4/3.4) inhibitor (IC50 of 1.1 and 3.2 nM, respectively).XAF-1407 displays highly selectivity other relevant cardiac ion channels, with selectivity ratios for Kir3.1/3.4 of >2,000–8,000 fold up to >27,000 fold for Nav1.5 and Kir2.1, respectively.XAF-1407 potently and selectively inhibited Kir 3.1/3.4 and Kir 3.4/3.4, underlying the IK,ACh current.XAF-1407 treatment in horses prolonged atrial effective refractory period as well as decreased atrial fibrillatory rate significantly and successfully cardioverted atrial fibrillation (AF), although with a decreasing efficacy over time. XAF-1407 shortened atrioventricular-nodal refractoriness, without effect on QRS duration.
