GJA5 and atrial fibrillation: Thus, whereas Western blot analyses of samples from patients with paroxismal or chronic atrial fibrillation have demonstrated a reduction in Cx40 levels [336], others have described no changes [337], or even an increased amount of the protein in patients with ischemic heart disease undergoing coronary artery bypass surgery that subsequently developed atrial fibrillation [334] or in patients with chronic atrial fibrillation [333].