A 28-year-old woman presents with a two-week history of worsening dyspnea and palpitations. She now becomes breathless after climbing just one flight of stairs. Over the last few days, she has had to sleep propped up on three pillows and has been awakened from sleep gasping for air. She also notes swelling in her ankles. She immigrated to the U.S. from the Philippines two years ago. She recalls having several episodes of severe sore throat and painful, swollen joints during her childhood but never sought medical attention. She has no other significant past medical history and denies any chest pain, fevers, or illicit drug use.