Abstract
A 69-year-old man underwent upper and lower gastrointestinal endoscopic examinations for a detailed evaluation of diarrhea that had persisted for several months, which revealed multiple polyposis in the stomach, duodenum, colon, and terminal ileum. The histopathological findings also led to a diagnosis of Cronkhite-Canada syndrome (CCS). On admission, the patient had hypoalbuminemia and electrolyte abnormalities, including hypokalemia, and developed paroxysmal atrial fibrillation (Paf), although there were no apparent organic lesions in the heart. The patient's sinus rhythm was restored by electrical cardioversion, steroid therapy for CCS improved diarrhea symptoms and endoscopic findings, and the electrocardiogram findings were normal.