Association of serum free triiodothyronine with long-term outcome in heart failure patients receiving cardiac resynchronization therapy

Abstract

To explore the prognostic role of free triiodothyronine (FT3) on all-cause mortality and heart failure (HF) hospitalization in patients receiving cardiac resynchronization therapy (CRT). In this single-center retrospective cohort study, a total of 202 chronic heart failure (CHF) patients who had CRT implantation from January 2010 to December 2014 were enrolled. Clinical outcomes were defined as all-cause mortality (including heart transplantation) and new heart failure (HF) hospitalization. Patients were divided into three groups according to FT3 tertiles: FT3≤4.08 pmol/L group (n=67), FT3 4.09-4.71 pmol/L group (n=68) and FT3>4.71 pmol/L group (n=67). Kaplan-Meier analyses were performed for each outcome. Cox proportional-hazards regression analyses were used to evaluate the independent prognosis of FT3 in CRT treated patients. Patients in FT3≤4.08 pmol/L group tended to be older, with more women patients, and had lower estimated glomerular filtration rate (eGFR), hemoglobin and serum sodium concentration. They were also less frequently subjected to smoking, alcohol consumption and were less likely prescribed with renin-angiotensin-aldosterone system inhibitors. Also, this group had highest proportion of NYHA class Ⅳ patients. Kaplan-Meier analyses demonstrated that FT3 4.09-4.71 pmol/L group was associated with a significantly better survival (P=0.022) and less new hospitalizations for HF event (P=0.020). Cox regression analyses indicated that FT3 4.09-4.71 pmol/L was an independent protective factor for both all-cause mortality (HR=0.220, 95%CI: 0.069-0.700, P=0.011) and HF hospitalization (HR=0.490, 95%CI: 0.241-0.996, P=0.049). Left ventricular end diastolic diameter (LVEDd) enlargement was an independent risk factor of all-cause mortality(HR=1.043, 95%CI: 1.004-1.083, P=0.031). Patients in FT3 4.09-4.71 pmol/L group had the lowest risk of all-cause mortality and HF hospitalization after CRT implantation.