A 67-year-old man with a history of chronic obstructive pulmonary disease and hypertension, presented to his physician 2 months ago with complaints of palpitations. He was noted to be in atrial fibrillation. He was begun on anticoagulation. After 1 month of anticoagulation his physician began therapy with sotalol as therapy of the arrhythmia. He returned for a follow-up visit 1 week later. What is the diagnosis?