Induction therapy with Thymoglobulin after heart transplantation: Impact of therapy duration on lymphocyte depletion and recovery, rejection, and cytomegalovirus infection rates

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 (>= 1 B) within the first year (7% vs 22%, p = 0.02). No humoral rejection occurred. At 1 year, freedom from rejection was 93% in the Thym07 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.