Pathological assessment of end-stage heart failure in explanted hearts in correlation with hemodynamics in patients undergoing orthotopic heart transplantation

Background: To date, there has been little research, if any, on the pathological correlates of end-stage heart failure in the explanted hearts of orthotopic heart transplant (OHT) recipients in correlation with the patients' hemodynamics. We sought to compare the gross and histopathological parameters in hearts explanted-native or previously transplanted-from patients with end-stage heart failure with the clinical hemodynamics parameters at the time of OHT. Methods: Forty patients undergoing OHT were enrolled in this study and divided into two groups according to whether they suffered from ischemic (ICMP) or nonischemic cardiomyopathy (NICMP). All study patients were treated with OHT for end-stage heart failure at The University of Texas Health Science Center at Houston. The pathological investigations of the hearts were focused on the study of the underlying cause of heart failure leading the patient to OHT; on the quantification of the extent and severity of fibrosis, hypertrophy, and myocytolysis; and on validating a semiquantitative grading scale. Analyses of multiple sections of the explanted hearts were carried out. The heart weights were recorded and compared with the grades of fibrosis, hypertrophy of cardiomyocytes, and myocytolysis. The grades of fibrosis, hypertrophy, and myocytolysis were evaluated in right and left ventricles and atria (with areas of confluent infarction excluded). The pathological parameters were correlated with the patients' clinical parameters. Results: Twenty-two patients (20 men, 2 women, mean age±S.E.M., 62.3±2.2 years) suffered from ICMP and 18 patients (9 men, 9 women, mean age±S.E.M., 56.3±2.8 years) from NICMP. All the clinical and pathological measured variables were comparable between the two groups, except for pulmonary vascular resistance, which was higher in the NICMP group of patients, and the grade of myocytolysis, which was significantly higher in the ICMP vs. NICMP group. Most of the clinical and pathological variables were overall linearly correlated. Conclusions: Both ICMP and NICMP groups of end-stage heart failure requiring OHT presented high grades of fibrosis, hypertrophy, and myocytolysis. Heart failure is the final common pathway of a variety of primary cardiovascular diseases regardless of the ischemic or nonischemic nature of the cardiomyopathy.