Early activation of an altered thyroid hormone profile in asymptomatic or mildly symptomatic idiopathic left ventricular dysfunction

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.