[Improvement in functional capacity after levothyroxine treatment in patients with chronic heart failure and subclinical hypothyroidism]

Abstract

Aim: To assess whether levothyroxine treatment improves functional capacity in patients with chronic heart failure (New York Heart Association class i-iii) and subclinical hypothyroidism.

Methods: One hundred and sixty-three outpatients with stable chronic heart failure followed up for at least 6 months were enrolled. A physical examination was performed, and laboratory tests including thyroid hormone levels, Doppler echocardiogram, radionuclide ventriculography, and Holter monitoring were requested. Functional capacity was assessed by of the 6-min walk test. Patients with subclinical hypothyroidism were detected and, after undergoing the s6-min walk test, were given replacement therapy. When they reached normal thyrotropin (TSH) levels, the 6-min walk test was performed again. The distance walked in both tests was recorded, and the difference in meters covered by each patient was analyzed.

Results: Prevalence of subclinical hypothyroidism in patients with heart failure was 13%. These patients walked 292±63m while they were hypothyroid and 350±76m when TSH levels returned to normal, a difference of 58±11m (P<.011). Patients with normal baseline TSH levels showed no significant difference between the 2 6-min walk tests.

Conclusions: Patients with chronic heart failure and subclinical hypothyroidism significantly improved their physical performance when normal TSH levels were reached.

Keywords: Capacidad funcional; Functional capacity; Heart failure; Hipotiroidismo subclínico; Insuficiencia cardíaca; Subclinical hypothyroidism.