Does the induction immunotherapy (basiliximab) influence the early acute cellular rejection index after orthotopic heart transplantation?- Preliminary assessment report.

The study aimed to determine the influence of induction therapy on the acute cellular rejection (ACR) index in adult heart transplant recipients during the one-year observation. The study population consisted of 256 consecutive adult patients (pts), aged 51.5 (±11.9) years, 199 (77%) men treated with orthotopic heart transplantation (OHT) in the period between 2015 and 2020 in a single high-volume heart transplant center. The endomyocardial biopsies (EMBs) were performed according to the protocol consisting of 7 protocolary EMBs for up to 3 months and 10 EMBs for up to one year after OHT. The rejection index (ACRI) was calculated as the number of scheduled EMBs with the ACR ≥ 2 divided by the total number of protocolary EMBs. The study population was divided into two groups according to the application of basiliximab. The total number of pts. who received basiliximab was 10 (3.9%). The main indications for the usage of the induction therapy were heart retransplantation, mechanical circulatory support (MCS), severe renal insufficiency (eGFR <30 mL/min/1.73 m2), and a panel of reactive antibody (PRA) > 10%. In the group with induction, the mean age was 49 (±14) years; 3 (30%) patients had the MCS prior to OHT, and 3 (30%) patients had heart retransplantation. Four (40%) patients had diabetes mellitus, and 4 (40%) patients had severe renal insufficiency. As maintenance therapy during the observation period, tacrolimus was given to 10 (100%) patients, everolimus to 2 (20%) patients, and MPA to 9 (90%) patients. In the group with no induction, the mean age was 51.8 (±12) years, MCS was used in 56 (23%) patients, 2 (0.8%) patients were retransplanted; 10 (4%) patients had eGFR <30 mL/min/1.73 m2 and 58 (24%) patients had diabetes. Tacrolimus was administered to 243 (99%) patients, cyclosporine to 3 (1%), everolimus to 40 (16%), and mycophenolate to 245 (99.6%) heart recipients. The median one-year ACRI was 0.0, IQR:0.0-0.08 in the group with induction vs. 0.077, IQR: 0.0-0.154 with no induction; p = 0.11. ACRI up to three months was significantly higher in the entire cohort in comparison to up to one year (P < 0.01). The multivariate analysis showed that only everolimus implementation and younger age at the time of transplant influenced patients' mortality rate (P < 0.01). Significant graft rejections (≥ 2R ISHLT) are most common in the first three months after OHT. Patients who are initially at high risk of significant cellular rejection may benefit from induction therapy.