PITX2 and atrial fibrillation: Experimental studies of Pitx2-induced AF have indicated that the downregulation of Pitx2 creates a predisposition to AF without marked structural changes in the atria [11,15,18,22] via shortened atrial repolarisation [22], a more depolarised resting membrane potential (RMP) [18], and abnormalities in calcium cycling [17,23,24].