GJA1 and atrial fibrillation: Although some studies indicated that genetic Cx43 up‐regulation or pharmacological enhancement of intercellular communication via gap junctions is anti‐arrhythmic,21, 22 there are also studies reporting excessive expression of Cx43 in arrhythmic animal models 4, 23, 24 or in atrial biopsy of patients with atrial fibrillation.25, 26