Thyroid dysfunction linked to worse survival in chronic HF
Patients with chronic HF and hyperthyroidism or hypothyroidism have increased risk for death compared with patients with normal thyroid levels, according to a retrospective analysis published in the American Journal of Cardiology.
“Subclinical thyroid dysfunction is very common in patients with chronic HF, and patients with thyroid dysfunction have reduced survival compared to euthyroid patients,” Nathan A. Samuel, BSc, with the department of academic cardiology at Hull York Medical School and the Hull and East Yorkshire Medical Research and Teaching Centre at Castle Hill Hospital, Cottingham, Kingston upon Hull, United Kingdom, told Healio. “There is a U-shaped relation between thyroid-stimulating hormone and outcome. However, in multivariate analysis, the association between thyroid dysfunction and mortality disappears after adjustment for established prognostic indicators such as increasing age, natriuretic peptide level and higher NYHA class.”
The analysis included 6,782 patients with chronic HF from the Hull LifeLab registry referred to a community HF clinic from March 2000 to March 2018.
Thyroid hormones were measured during each patient’s initial visit to the HF clinic. Euthyroid state was defined as a thyroid-stimulating hormone (TSH) level between 0.35 mIU/L and 4.7 mIU/L, hypothyroidism was defined as TSH more than 4.7 mIU/L and hyperthyroidism was defined as TSH less than 0.35 mIU/L.
In total, 90% of patients were euthyroid, 6% were hypothyroid and 4% were hyperthyroid.
In the univariable analysis, patients with hypothyroidism (HR = 1.25; 95% CI, 1.08-1.45) and patients with hyperthyroidism (HR = 1.21; 95% CI, 1.01-1.46) had increased risk for death compared with euthyroid patients. Elevated TSH predicted mortality in the univariable analysis (HR = 1.02; 95% CI, 1.01-1.03), but researchers did not observe this association in the multivariable analysis.
“It is important to check thyroid function at baseline in patients with newly diagnosed HF since both hypo- and hyperthyroidism can cause HF,” Samuel said.
According to the researchers, the three strongest predictors of adverse outcomes in this patient population were increased age, increased pro-B-type natriuretic peptide and higher NYHA HF class.
“Our findings can help clinicians in risk prediction. Although thyroid dysfunction was not independently associated with increased mortality in our study, it was a marker of unwell patients with reduced survival,” Samuel said. “The priority for these patients should be to receive optimal medical therapy for heart failure, which has been shown to improve life expectancy up to three times.”
According to Samuel, the impact of thyroid dysfunction on the quality of life of patients with HF is currently being investigated.
For more information:
Nathan A. Samuel, BSc, can be reached at hyns8@hyms.ac.uk.
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