Early Activation of an Altered Thyroid Hormone Profile in Asymptomatic or Mildly Symptomatic Idiopathic Left Ventricular Dysfunction

Abstract 

Background

Although an altered thyroid metabolism has been documented in patients with overt heart failure, no evaluation has been made of a heart-thyroid interaction in mildly symptomatic patients with idiopathic left ventricular dysfunction (ILVD). We wanted to assess the thyroid state in patients with ILVD.

Methods and Results

Eighty-six patients (age 60 ± 10 years) were enrolled into the study. Thyroxine (T4), triiodothyronine (T3), thyrotropin, brain and atrial natriuretic peptides (BNP, ANP), noradrenaline, aldosterone, renin activity, and interleukin-6 were measured. Patients were divided into three groups: Group N with LV ejection fraction (EF) ≥50% (n = 28), Group I with LVEF >35%–<50% (n = 34), Group II with LVEF ≤35% (n = 24). There was a significant correlation between T3 and LVEF (r = 0.25, P = .02) and a negative correlation between T3 and BNP (r = –0.37, P < .0001). At univariate analysis T3 was a predictor of LV dysfunction, whereas BNP was the most important predictor at multivariate analysis (P = .002). T3 was the only predictor of New York Heart Association class at multivariate analysis.

Conclusion

An altered thyroid profile characterized by a reduction in peripheral production of biologically active T3 is related to LV dysfunction and early symptoms of heart failure in patients with ILVD.

Key Words: Idiopathic cardiomyopathy, Natriuretic peptides, Thyroid