Perioperative thyroid dysfunction and outcome after heart transplantation

Abstract

Introduction Thyroid dysfunction after serious systematic stress is a widely known phenomenon., called non-thyroidal illness syndrome or euthyroid sick syndrome. Triiodothyronine (T3) and tetra iodothyronine (T4) decrease without previous thyroid disorders could be an early sign. Current phenomenon in our special, critically ill patient population is not well-studied yet. Methods Our single centre retrospective study was approved by the IRB (65/2017). The data of patients undergoing orthotopic heart transplantation between January 2015 and January 2019 were analysed. Data on survival was refreshed on the 2nd of May 2019. Demographic variables, thyroid diseases and hormone replacement therapy in medical history, the United Network for Organ Sharing (UNOS) score, baseline T3 and T4 levels (pmol/L) and postoperative complications were collected into our dataset. Our primary outcome was 30-day mortality, secondary outcomes were overall and in-hospital mortality. For further analysis, multivariable Cox regression were applied. Results Final analysis included 75 patients, 26.7% (n = 20) were female. Median time of follow-up was 592 day (IQR25-75: 395-839). Thirty-day, overall and in-hospital mortality were 6.7% (n = 5), 12% (n = 9) and 9.3%(n = 7), respectively. Median T3 level was 2.94 pmol/L (IQR25-75: 2.40-3.85) and T4 level was 14.34 pmol/L (IQR25-75: 11.87-16.36). Twelve (16%) patients had hypothyroidism in their medical history and 8 (10.7%) patients had hyperthyroidism, 9 (12%) patient were on thyroid hormone replacement therapy before the procedure. Median age was 52 year (IQR25-75: 45-58), median UNOS score was 3 (IQR25-75: 2-5). After adjustment of the UNOS score, T4 level were independently associated with 30-day (OR: 1.10; 95% CI: 1.01-1.21; p = 0.038) and in-hospital mortality (OR: 1.10; 95% CI: 1.01-1.20; p = 0.031). Nevertheless, T3 level showed no associations with our outcomes. Discussion Thyroid function should be monitored in the perioperative period of heart transplantation, dynamics of T4 may represent a clinically important marker. Thyroid hormone replacement in the early phase might need further investigations.