A Case of Rapidly Progressive Dyspnea on Exertion

A 51-year-old woman presented to the emergency room with progressive dyspnea on exertion. She was an avid runner, and had completed a half-marathon 2 months before presentation. Since then, she had experienced a rapid decline in exercise capacity such that, on presentation, she was unable to climb a flight of stairs without stopping to catch her breath. She had recently completed a course of azithromycin prescribed by her primary care physician without benefit. She denied chest pain, lower extremity swelling, fevers, chills, or cough. She had had stage II left breast adenocarcinoma successfully treated 2 years before with Adriamycin-containing chemotherapy, radiation to the left chest, and bilateral mastectomy. Her only medication was fexofenadine for seasonal allergies. She had no previous heart disease or cardiovascular risk factors, with the exception of a distant 10–pack-year smoking history. She had no family history of premature cardiovascular disease. There was no history of illicit substance abuse.