Thymoglobulin Administered Early After Heart Transplantation Reduces Early Myocardial Hypertrophy Assessed by Morphometric Studies

The aim of this study was to assess the effects of early thymoglobulin administration on cardiocyte nuclear status in orthotopic heart transplant (OHT) recipients.Material and MethodsWe investigated endomyocardial biopsies (EMBs) from 31 OHT recipients and 10 control cases. OHT patients were divided into the standard group who were treated without thymoglobuline; an ATG group who received thymoglobulin electively, and a standard+ATG group who were administered thymoglobulin upon a drop in renal function. We evaluated only EMBs obtained at 1 and 4 weeks after OHT showing no significant rejection (ISHLT grades 0 to 1B). The morphometric studies were performed using a computerized, automated Quantimet image analysis system. Overall, 1750 cardiocyte nuclei were quantitated for area, length, breadth, perimeter, chromatin median grey level, and fullness factor. Statistical analysis was performed using the Mann- Whitney U test, the Wilcoxon test, and discriminant analysis.ResultsAll OHT groups showed significantly higher values (indicating nucleus enlargement) than the control group. All factors suggesting myocardial hypertrophy were significantly higher in the standard group; however, they decreased significantly with time. In contrast, the nuclear geometric parameters were significantly lower and stable throughout the study in the ATG group. The results of the standard+ATG group were intermediate, and their normalization as incomplete at the week 4 examination. Discriminant analysis revealed the closest Mahalanobis distance between control and ATG groups both at and weeks 1 and 4 after OHT.ConclusionThymoglobulin administered early after surgery protected cardiocyte hypertrophy in heart transplant recipients, mitigating graft ischemic damage.