Review Question - QID 213822

A 33-year-old woman presents to the emergency department with shortness of breath. She states that it has been ongoing for the past 5 years; however, she recently immigrated to this country and has never seen a doctor before. She also endorses palpitations which are occurring currently. She denies fevers, chills, chest pain, or myalgias. She has a chronic cough for which she has taken multiple courses of antibiotics that she bought from a family member without resolution of her symptoms. Her temperature is 97.5°F (36.4°C), blood pressure is 122/82 mmHg, pulse is 50/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam is notable for a thin, young woman with dry skin. Her hair is thin as well. Abdominal exam is nontender in all quadrants. Lower extremity edema is noted. An ECG is performed as seen in Figure A. A chest radiograph is ordered and is pending. Which of the following is the most likely diagnosis?