Review Question - QID 214718

A 62-year-old woman presents to the emergency department for shortness of breath and chest pain. She states that she has difficulty climbing stairs and walking more than 1 block due to shortness of breath and chest pain when she was previously able to do so without issue 3 months ago. Her chest pain is substernal and worsens with exertion but improves with rest. She denies any fevers, chills, or changes in her urinary or bowel patterns. She has a medical history of hypertension and hyperlipidemia. Approximately 25 years ago, she was diagnosed with Hodgkin lymphoma which was treated with chemotherapy and radiation therapy. Her temperature is 99°F (37.2°C), blood pressure is 145/85 mmHg, pulse is 90/min, and respirations are 20/min. Physical examination is remarkable for an S3 heart sound, bibasilar crackles, pericardial friction rub, and mild lower extremity edema. An echocardiogram demonstrates an ejection fraction of 55%, dilated left atrium, and sclerotic appearing mitral and aortic valves. Coronary angiography reveals narrowing of the left anterior descending artery. Which of the following is most likely the cause of this patient’s constellation of symptoms?