Abstract Body (Do not enter title and authors here): Background: Thyroid hormone (TH) supplementation is a well-known guideline recommendation for eligible donors of heart transplantation. However, few research data demonstrated a benefit of this therapy, and some suggest higher rates of graft failure. Therefore, we aim to expand on previous literature through a systematic review and meta-analysis comparing TH therapy to placebo in potential heart transplant donors.

Methods: We systematically searched Embase, Pubmed and Cochrane for randomized controlled trials (RCT) and observational studies comparing TH therapy to placebo in heart donors. We focused on the following outcomes: (1) receptor graft complications; (2) all-cause mortality; and (3) retransplantation. A subgroup analysis was performed according to graft complications: (1) dysfunction; (2) failure; (3) loss; and (4) survival.

Results: We included six studies, of which 2 were RCTs. A total of 16,452 were analyzed, of whom 10,573 (64.3%) underwent TH supplementation. The follow-up period ranged from 30 days to 10 years. The included subjects were mostly male (69.1%), with a mean age of 30.6 years. In the pooled analysis, we found no significant difference between groups in graft complications (Figure 1;RR 0.94; 95% CI 0.52-1.69; p=0.83), all-cause mortality (RR 1.13; 95% CI 0.64-2.00; p=0.67), and retransplantation rates (RR 1.21; 95%CI 0.64-2.26; p=0.55). Subgroup analysis of graft complications demonstrated similar results between groups (p=0.29).

Conclusion: In our meta-analysis of heart transplant donors, TH therapy was associated with similar rates of all-cause mortality, graft complications and retransplantation rates compared to the placebo group. It is important that further studies be conducted to reassess the guidelines regarding the use of TH in eligible heart transplant donors.