Thyroid Function at Left Ventricular Assist Device (LVAD) Implantation Predicts Prognosis During LVAD Support

Abstract

<h3>Purpose</h3> The purpose of this study was to assess thyroid status before and during left ventricular assist device (LVAD) support and to estimate an impact of thyroid status at LVAD implantation on survival. <h3>Methods</h3> We retrospectively analyzed thyroid function profile including thyroid- stimulating hormone (TSH), free triiodothyronine (fT₃), and free thyroxine (fT₄) in a group of all consecutive 147 patients (93.2%- male, BMI-26.7 ±5.6, mean and median INTERMACS profile- 3; 53% -ischemic etiology of heart failure) implanted with continuous-flow LVAD in our institution within years 2009-2021 (54%-HeartMate3; 40%- HeartWare; 6%- Heart Mate II). One year survival was 78.3%. Fifteen percent of patients received amiodarone, whereas 20.4%- supplementation of levothyroxine and 2% - thyreostatic treatment during LVAD support. Statistical methods used were: ROC curves, when Youden factor > 0.27- Chi 2 test, analysis of variance, Bonferroni test. <h3>Results</h3> Mean values of TSH, fT₃ and fT₄ were respectively 2.33 ± 1.69 uIU/ml; 2.14± 0.56 pg/ml; 1.25 ± 0.36 ng/dl before, 2.95 ± 3.18 uIU/ml; 2.47±1.35 pg/ml; 1.11 ±0.27 uIU/ml and 2.0 ±1.27 ng/dl; 2.43 ±0.42 pg/ml; 1.22 ± 0.25 ng/dl at 3 months and at 12 months post LVAD implantation. Mortality risk was 2.8 times lower for patients presenting TSH ≥ 1.29 uIU/ml (p= 0.01) and 3.8 times lower for patients presenting fT₃ ≥ 1.93 uIU/ml (p=0.003) at LVAD implantation. TSH significantly decreased between 3 and 12 months of LVAD support (Bonferroni test, p<0.009), whereas fT3 increased significantly after 3 and 12 months as compared to values before LVAD implantation (Bonferroni test, p < 0.039 and p<0.041 respectively). <h3>Conclusion</h3> Thyroid function may have an impact on survival in patients with end-stage heart failure implanted with LVAD. Thyroid status surveillance and its corrections could improve the overall prognosis in this group of patients. Further studies are needed to confirm this thesis.