CCN2 and atrial tachycardia: After eight weeks of atrial tachycardia pacing, the electrocardiography, transthoracic echocardiography, hematoxylin-eosin staining, and Masson’s staining of the right atrial appendages were performed along with the immunohistochemistry, quantitative real-time polymerase chain reaction, and Western blot analysis of connective tissue growth factor, collagen I, and collagen III.