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A 52-year-old woman is referred by her family physician to a general internist’s clinic for assessment of a 3-month history of exertional dyspnea. She also reports a nonproductive nocturnal cough, night sweats, and an 18-lb weight loss over the preceding 3 months. The patient denies any history of chest pain, palpitations, presyncope, or syncope. The patient has a history of chronic obstructive pulmonary disease for which she was admitted to hospital 3 times in the last several months. Each time, she received a course of antibiotics and oral glucocorticoids, with no relief of her dyspnea. She reports no prior cardiac history, history of malignancies, or venous thromboembolic disease. Her home medications include salbutamol and tiotropium. She is a current smoker, with a 40–pack-year history, and denies alcohol intake or recreational drug use.