Cx43 is expressed in both atrial and ventricular myocytes as well as in the Purkinje fibers, and deficiencies in Cx43 expression or in the organization and distribution of gap junctions have been linked to the development of arrhythmias in patients with heart failure and other cardiomyopathies [29,30,31]. This evidence concerns the gene GJA1 and cardiac arrhythmia.