Association Between Time-in-Therapeutic Tacrolimus Range and Early Rejection After Heart Transplant

Area of Science:

• Cardiology
• Transplantation Immunology
• Pharmacology

Background:

• Heart transplant recipients often face pressure for rapid achievement of therapeutic tacrolimus levels.
• Tacrolimus is a key immunosuppressant to prevent rejection after heart transplantation.
• Early immunosuppression management is critical for graft survival and patient outcomes.

Purpose of the Study:

• To evaluate the association between time to and time within the therapeutic tacrolimus range and acute rejection.
• To determine if early achievement of target tacrolimus levels impacts 30-day post-heart transplant rejection rates.
• To analyze the predictive value of tacrolimus pharmacokinetics on early graft outcomes.

Main Methods:

• Single-center retrospective cohort study of adult heart transplant recipients.
• Tacrolimus therapeutic range defined as 10-15 ng/ml trough levels.
• Analysis of time to therapeutic trough and time-in-therapeutic range (Rosendaal method) against clinical and histologic rejection (grades 1R/1B, 2R+).

Main Results:

• No significant difference in median time to therapeutic tacrolimus levels between rejection and no-rejection groups (9.5 vs 9.0 days, p=0.623).
• Median time-in-therapeutic tacrolimus range was similar in both groups (34.1% vs 36.2%, p=0.512).
• No significant association found between time to/in therapeutic range and 1R/1B or 2R+ histologic rejection.

Conclusions:

• Neither the time to achieve therapeutic tacrolimus levels nor the time spent within this range predicted acute rejection within 30 days post-heart transplant.
• These findings challenge the perceived necessity for rapid tacrolimus normalization in the early post-transplant period.
• Further research may be needed to identify other predictors of early acute rejection in heart transplant patients.