Heart block and hyperthyroidism. Report of two cases.Arch Intern Med. 1975 Aug; 135(8):1091-5.AI
In two patients with hyperthyroidism who had no signs of heart disease, first-degree heart block with tall and large P waves occurred. In one patient, a left bundle-branch block and transient complete heart block with Stokes-Adams episodes also occurred, although there was no verifiable evidence of acute inflammatory disease.