Samuel NA, Cuthbert JJ, Brown OI, et al. - Researchers explored the connection between thyroid function and prognosis in a large, well-characterized cohort of ambulatory patients with chronic heart failure (CHF). Two thousand nine hundred ninety-seven patients had heart failure with reduced ejection fraction and 1,995 patients had heart failure with normal ejection fraction. In univariable analysis, both hypothyroid patients and hyperthyroid patients were at higher risk of death compared with euthyroid patients. A U-shaped relation between thyroid-stimulating hormone and outcome was established. Increasing age, increasing amino-terminal pro-B-type natriuretic peptide, and higher NYHA class were the three strongest predictors of adverse outcome. Although thyroid dysfunction in patients with CHF is associated with poorer survival, it is not an independent predictor of mortality.