Induction Therapy With Thymoglobulin After Heart Transplantation: Impact of Therapy Duration on Lymphocyte Depletion and Recovery, Rejection, and Cytomegalovirus Infection Rates

TLDR: The 7-day treatment led to more efficient and prolonged lymphocyte depletion and significantly less rejection at 1 year, without an increase in cytomegalovirus infection rate.

Abstract: Background This retrospective single-center study compared lymphocyte depletion in 144 heart transplant recipients using 2 different induction protocols with Thymoglobulin (Genzyme Transplant, Cambridge, MA). Methods Thymoglobulin (1.5 mg/kg) was given to 105 patients for 7 days (Thymo7) and 39 patients for 5 days (Thymo5). Results Patient clinical characteristics were similar except that the Thymo7 group had a higher prevalence of women (33% vs 15%, p = 0.04), gender mismatch (35% vs 19%, p = 0.07), donor African American race (19% vs 2%, p = 0.008), older donor age (35 ± 13 vs 31 ± 12, p = 0.08), and higher pre-transplant creatinine (1.43 ± 0.67 vs 1.25 ± 0.48 mg/dl, p = 0.095). Seventy-five percent of the Thymo7 group reached target (absolute lymphocyte count ≤200) and 42% at 21 days ( p = 0.002). Thymo7 patients had significantly lower rejection rates (≥1B) within the first year (7% vs 22%, p = 0.02). No humoral rejection occurred. At 1 year, freedom from rejection was 93% in the Thymo7 group vs 80% in the Thymo5 group ( p = 0.007), and cytomegalovirus disease (9% and 5%, p = 0.5) and bacterial infection (26% vs 32%, p = 0.5) were similar. One-year actuarial survival was 92% ± 3% in the Thymo7 and 100% in the Thymo5 group ( p = 0.07), and at 3 years, 85 ± 4% and 90 ± 6%, respectively ( p = 0.4). Conclusions Both Thymoglobulin regimens were well tolerated. The 7-day treatment led to more efficient and prolonged lymphocyte depletion and significantly less rejection at 1 year, without an increase in cytomegalovirus infection rate.