Necropsy findings in heart transplant recipients with and without primary graft dysfunction: a retrospective study

Abstract Background Primary graft dysfunction (PGD) is the leading cause of death in the first year after heart transplant (HT). Physiopathology of PGD is not clear, and histological findings are not defined in literature. Purpose The objective of this study is to describe the morphological findings in the hearts of patients who died within the first 14 days after HT and to compare findings between 2 groups: a group with the diagnosis of PGD and a group without PGD. Methods We included all adult patients submitted to HT in one center who died within the first 14 days after the procedure and were submitted to necropsy between January 1st, 2013 and March 31st, 2020. Demographic, perioperative, histological and immunohistochemical data on heart slides obtained on necropsy were recorded retrospectively. We retrospectively analyzed if the patients met the ISHLT criteria for PGD, and then we categorized them in two groups: PGD group or non-PGD group. All heart slides were reviewed by an experienced pathologist considering the presence of histological features of acute cellular rejection, antibody-mediated rejection, necrosis and its morphological characteristics if present. Pathologist was blind for each patient group. We considered the necrosis significant if it took more than 10% of the examined area. All findings were compared between groups. Results Among 322 HTs performed, 31 patients died within 14 days after the procedure. Five patients were not subjected to autopsy, and the remaining 26 patients were included. Twelve patients presented PGD, while 14 patients did not. Comparison between groups shows longer ischemia time, higher incidence of pre-transplant mechanical circulatory support, lower post-transplant left ventricular ejection fraction and higher incidence of post-transplant right ventricular dysfunction in PGD group (Table 1). Necropsy findings were similar between groups and four patterns of necrosis were found, namely microcalcified, contraction-band, coagulative and liquefactive necrosis (Table 2). Necrosis was detected in the 80.7% of all cases, taking more than 10% of the myocardial area in 46.1% of them. Seven patients (26.9%) presented signs of mild cellular rejection (1R). One of them had also antibody-mediated rejection. One patient presented hyperacute graft rejection. The cause of death was defined by necropsy in 21 cases. The most common cause of death in PDG group was cardiogenic shock (66.7%), while in non-PGD group septic shock (28.5%) and bleeding (21.4%) were the most common causes. Conclusion While left ventricular ejection fraction was significantly lower in PGD group, necrosis was a frequent finding both groups, raising the hypothesis maybe necrosis is not directly the cause of cardiac dysfunction in PGD. More studies are needed to fully understand PGD pathology.Table 1Table 2