A 45-year-old man receives a cardiac allograft for dilated cardiomyopathy. He has no problems with rejection, but 5 years later he has worsening exercise tolerance with increasing dyspnea and peripheral edema. Echocardiography shows a reduced ejection fraction of 35%. Which of the following pathologic abnormalities has he most likely developed in the allograft?

Nearly every allograft develops some degree of arteriopathy within 10 years, and half of the patients have significant arteriopathy by 5 years following transplantation. Unlike atherosclerosis, the smaller coronary artery branches are preferentially affected, but the result is the same: ischemic damage. The inflammation that may come from rejection is not a risk for amyloid deposition. A transplanted heart does not have a functional pericardial sac, and though there may be some fibrous adhesions following surgery, they are not constrictive. Transplant recipients receiving immunosuppressive therapy have immune dysregulation that increases the risk for both carcinomas and lymphoid malignancies, but these are unlikely to involve the heart. The immunosuppression with antirejection drugs increases the risk for infection with opportunistic agents, but these are not common and they can often be treated.