Introduction Thyroid dysfunction is common in patients with chronic heart failure (CHF), but there is conflicting evidence regarding its prognostic significance. We investigated the relation between thyroid dysfunction and prognosis in a large, well characterised cohort of ambulatory patients with CHF.
Methods Heart failure was defined as signs and symptoms of the disease and either left ventricular systolic dysfunction (LVSD) mild or worse (heart failure with reduced ejection fraction (HeFREF)), or no LVSD and raised amino-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (>125 ng/L) (heart failure with normal ejection fraction (HeFNEF)). Euthyroid was defined as a TSH level between 0.35–4.70 mIU/l, hypothyroidism as >4.70 mIU/L, and hyperthyroidism as <0.35 mIU/L. The primary outcome was all-cause mortality.
Results 2997 patients had HeFREF and 1995 patients had HeFNEF. 4491 (90.0%) patients were euthyroid, 312 (6.3%) were hypothyroid, and 189 (3.8%) were hyperthyroid (Table 1). In univariable analysis, both hypothyroid patients (hazard ratio (HR) 1.25, 95% confidence interval (CI) 1.08 to 1.45) and hyperthyroid patients (HR 1.21, 95% CI 1.01 to 1.46) had a greater risk of death compared to euthyroid patients (Figure 1). There was a U-shaped relation between TSH and outcome (Figure 2). Increasing TSH was a predictor of mortality in univariable analysis (HR 1.02, 95% CI 1.01 to 1.03), but the association disappeared in multivariable analysis (Table 2). The three strongest predictors of adverse outcome were age, increasing NT-proBNP, and higher NYHA class.
Conclusion Although thyroid dysfunction is associated with worse survival in patients with CHF, it is not an independent predictor of mortality.
Conflict of Interest None
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