A Low-Normal Free Triiodothyronine Level Is Associated with Adverse Prognosis in Euthyroid Patients with Heart Failure Receiving Cardiac Resynchronization Therapy

Abstract

SummaryThyroid dysfunction is prevalent in patients with heart failure (HF) and hypothyroidism is related to the adverse prognosis of HF subjects receiving cardiac resynchronization therapy (CRT). We aim to investigate whether low-normal free triiodothyronine (fT3) level is related to CRT response and the prognosis of euthyroid patients with HF after CRT implantation.One hundred and thirteen euthyroid patients who received CRT therapy without previous thyroid disease and any treatment affecting thyroid hormones were enrolled. All of patients were evaluated for cardiac function and thyroid hormones (serum levels of fT3, free thyroxine [fT4] and thyroid-stimulating hormone [TSH]). The end points were overall mortality and hospitalization for HF worsening. During a follow-up period of 39 ± 3 weeks, 36 patients (31.9%) died and 45 patients (39.8%) had hospitalization for HF exacerbation. A higher rate of NYHA III/IV class and a lower fT3 level were both observed in death group and HF event group. Multivariate Cox regression analyses disclosed that a lower-normal fT3 level (HR = 0.648, P = 0.009) and CRT response (HR = 0.441, P = 0.001) were both independent predictors of overall mortality. In addition, they were also both related to HF re-hospitalization event (P < 0.01 for both). Patients with fT3 < 3.00 pmol/L had a significantly higher overall mortality than those with fT3 !3.00 pmol/L (P = 0.027). Meanwhile, a higher HF hospitalization event rate was also found in patients with fT3 < 3.00 pmol/L (P < 0.001).A lower-normal fT3 level is correlated with a worse cardiac function an adverse prognosis in euthyroid patients with HF after CRT implantation.(Int Heart J 2017; 58: 908-914) Key words: Thyroid hormones, Cardiac dysfunction, Left ventricular dyssynchrony, CRT response, Mortality, Hospitalization C ardiac resynchronization therapy (CRT) is a considerable treatment for patients with drugrefractory heart failure (HF) and electromechanical dyssynchronoy.1,2) Though CRT improves heart failure symptoms and quality of life, and reduces both HF-related morbidity and mortality, non-response to CRT has been reported in nearly one third of patients.3) The reason of non-response to CRT is complicated and remains a question of different opinions.Thyroid hormones (THs) have cardiac and vascular effects, and they also regulate biochemical reactions in most tissues.4) TH consists of thyroxine (T4) and triiodothyronine (T3), and the cardiac myocyte does not convert T4 to T3. In other word, T3 is the bioactive form of thyroid hormone for cardiomyocytes and plays an important role in cardiovascular regulation. Many studies have confirmed that T3 is a prognostic predictor or risk stratification of HF.5-7) Recently, fT3 level was shown to be associated with cardiac function and heart structure in euthyroid subjects without HF.8) In addition, another research reported hypothyroidism was associated with a worse prognosis after CRT implantation, but it did not supply values for complete thyroid panel (fT3 and fT4). 9) Is the prognos...

Outcomes of Cardiac Resynchronization Therapy in Patients with Hypothyroidism and Heart Failure

“…Hypothyroidism is associated with a higher mortality rate, cardiovascular events, and progression of chronic kidney disease and diabetes 1, 2, 10, 17-19 . Similarly, Chen's study found that a low-normal free triiodothyronine level was associated with HF rehospitalization and overall mortality in euthyroid patients with HF receiving CRT 20 . Not surprisingly, our patients with hypothyroidism had higher allcause mortality than those with euthyroidism despite CRT, an indication that survival is substantially associated with systemic diseases and comorbidities in HF.…”

Outcomes of Cardiac Resynchronization Therapy in Patients with Hypothyroidism and Heart Failure

“…Hypothyroidism is associated with a higher mortality rate, cardiovascular events, and progression of chronic kidney disease and diabetes 1,2,10,[17][18][19] . Similarly, Chen's study found that a low-normal free triiodothyronine level was associated with HF rehospitalization and overall mortality in euthyroid patients with HF receiving CRT 20 . In contrast, similar risk of all-cause mortality was found in our patients with hypothyroidism or euthyordism.…”

Outcomes of Cardiac Resynchronization Therapy in Patients with Hypothyroidism and Heart Failure

“…Hypothyroidism is associated with a higher mortality rate, cardiovascular events, and progression of chronic kidney disease and diabetes [ 1 , 2 , 10 , 17 – 19 ]. Similarly, Chen’s study found that a low-normal free triiodothyronine level was associated with HF rehospitalization and overall mortality in euthyroid patients with HF receiving CRT [ 20 ]. In contrast, similar risk of all-cause mortality was found in our patients with hypothyroidism or euthyordism.…”