Essentials in the diagnosis of postoperative myocardial lesions similar to or unrelated to rejection in heart transplant

Background, objectives: Histological diagnosis of control biopsies in patients with heart transplant represents a significant step of monitoring, with a great influence on adjusting immunosuppressive treatment. Histological lesions are usually related to ischemia and reperfusion, with varying degrees of intensity. This study aimed to highlight the most important aspects of the histological diagnosis and differential diagnosis of postoperative myocardial lesions associated or unrelated to rejection in heart transplant. Materials and Methods: This retrospective study involved 53 patients who received cardiac transplant between 2000 and 2017. Patients were monitored by lesion quantification of endomyocardial biopsies, with diagnoses established based on biopsy material in the early, medium and late post-transplant periods. Hematoxylin eosin, Masson’s trichrome, and Van Gieson stains were used; immunohistochemical determinations used CD4, CD20, CD45, CD68, HLA-DR, VEGF and CD31. Results: Ischemia and reperfusion lesions were diagnosed on all biopsies in the first 6 weeks post-transplant. Nine cases of the Quilty effect were identified, and in 12 cases, the biopsies were performed on the same spot as previous biopsies. A significant number of transplanted patients presented cytomegalovirus that was difficult to diagnose on endomyocardial biopsies. Conclusions: The detailed study of ischemia and reperfusion lesions, as well as of changes un-related to rejection becomes a major objective in the short, medium and late post-transplant period. Overdiagnosis of rejection induces changes of the immunosuppressive therapeutic protocol, with alarming repercussions on cytomegalovirus reactivation, and risks of potentiating inflammation, myocyte destruction and the recurrence of disorders related to both inducing and aggravating heart failure.