A 68-year-old woman presents with an eight-month history of progressively worsening fatigue and shortness of breath on exertion. She also reports significant bilateral lower extremity swelling that has progressed to her thighs over the last three months, making it difficult to wear shoes. She sleeps on two pillows but denies paroxysmal nocturnal dyspnea. Her past medical history is significant for persistent atrial fibrillation and a mitral valve repair for severe degenerative regurgitation ten years ago. Her medications include metoprolol, apixaban, and a daily multivitamin.