Time to Discontinue Levothyroxine for Heart Organ Donors

While donation after cardiac death (DCD) is quickly gaining steam as a novel method for increasing the number of available organs for heart transplant surgery in the US, donation after brain death (DBD) is still the most common donation method.

Unfortunately, brain death causes significant physiologic derangements that can damage the potential donor heart and compromise transplantation. One identified was that hormonal insufficiency after brain death, especially thyroid hormone deficiency, leads to myocardial energy depletion and subsequent decline in cardiac function. This led to the use of levothyroxine supplementation to improve cardiac function and facilitate transplantation from brain-dead donors.

While thyroid supplementation has become widespread in the US, the data to support its use is very limited. In this week’s installment of Talking Therapeutics, we evaluate a recent randomized trial to address this gap in the evidence.

Talking Point: No Evidence for Benefit

In a trial dedicated to exploring intravenous levothyroxine for unstable brain-dead heart donors, 15 organ-procurement organizations in the US and randomly assigned hemodynamically unstable potential brain dead heart donors within 24 hours received an intravenous infusion of levothyroxine (30 μg per hour for a minimum of 12 hours) or saline placebo. The primary outcome was transplantation of the donor heart.

Overall, 800 patients were enrolled in this study. Study findings indicate that hearts were transplanted from 230 donors (54.9%) in the levothyroxine group and 223 (53.2%) in the saline group (adjusted risk ratio, 1.01; 95% CI, 0.97 to 1.07; P=0.57).

As a secondary endpoint, graft survival at 30 days was evaluated. This occurred in 224 hearts (97.4%) transplanted from donors assigned to receive levothyroxine and 213 hearts (95.5%) transplanted from donors assigned to receive saline (difference, 1.9 percentage points; 95% CI, −2.3 to 6.0; P<0.001 for noninferiority at a margin of 6 percentage points). Researchers also evaluated donor heart function and found that there were no differences in weaning from vasopressor therapy or ejection fraction on echocardiography.

Talking Point: Some Signals for Harm

The authors noted more cases of severe hypertension and tachycardia occurred in the levothyroxine group vs the control group. The adverse events, when combined with the absence of a benefit, confirm that health care professionals should no longer administer levothyroxine supplementation to brain dead heart transplant donors to facilitate transplantation.