Review Question - QID 213464

A 52-year-old man presents to the emergency department with 1-month of progressive dyspnea, decreased exercise tolerance, and inability to sleep flat on his back. He says that he been getting increasingly short of breath over the past few years; however, he attributed these changes to getting older. He started becoming very concerned when he was unable to climb the stairs to his apartment about 3 weeks ago. Since then, he has been experiencing shortness of breath even during activities of daily living. His past medical history is significant for heroin and cocaine use as well as periods of homelessness. Physical exam reveals a gallop that occurs just after the end of systole. Which of the following could lead to the same pathology that is seen in this patient?