A randomized trial comparing triiodothyronine (T3) with thyroxine (T4) for hemodynamically unstable brain-dead organ donors.
Dhar, R., Stahlschmidt, E. et al. (2019).
To determine whether T3 infusion can improve cardiac performance, haemodynamic stability, and result in more hearts transplanted than standard T4 therapy in haemodynamically unstable heart‐eligible brain dead (BD) organ donors.
Donors underwent echocardiography, within 12 hours of brain death and were randomised to T3 or T4 infusion for 8 hours.
37 BD donors were randomised (n=16 T3 vs n=21 T4).
Primary outcomes were assessed as incidence of myocardial dysfunction, improvement in left ventricular ejection fraction (LVEF) after 8 hours of treatment and proportion of donors with abnormal LVEF who achieve recovery to normal LVEF. Secondary outcomes comprised proportion of hearts that could be successfully transplanted, improvement in haemodynamic parameters and the change in free T3 and free T4 levels between groups after infusion.
This is a very interesting study comparing T3 with T4 infusions in brain dead donors prior to cardiac allograft retrieval. Whilst the randomisation process was fair and the allocation concealment maintained, the infusions were not blinded to the study clinicians. The study was not powered for the number of hearts transplanted, but for the proportion of hearts with normalised Left Ventricular Ejection Fraction (LVEF) after infusion. Based on previous cases, the authors assumed a normalisation rate of 85% versus 44% using data from different time-periods to power their study. However, during the study, both arms had a normalisation rate of approximately 50%. During this study baseline T3 and T4 levels were not low in donors prior to infusions starting. More hearts from donors receiving T3 were ultimately transplanted, however there were significant differences in the baseline characteristics of the groups that may explain this phenomenon: younger donors, less with left ventricular hypertrophy, more blood group O donors. Overall this study is likely to be underpowered to test the hypothesis, and cardiac stunning seemed to resolve regardless of free T3 levels after infusion.