Amiodarone, an iodine-containing antiarrhythmic drug frequently used in chronic heart failure (CHF) patients, is often the cause of primary hypothyroidism. It has not been well investigated, however, whether its use could lead to a poor prognosis in these patients by inducing and/or worsening thyroid function. The aim of this study was to evaluate the prognostic significance of hypothyroidism detection in CHF outpatients treated with amiodarone. Out of 355 patients affected by CHF, 107 (65±10 years, 89 male, NYHA 2.5±0.5, left ventricular ejection fraction, LVEF=29±8%) in stable clinical condition, treated with amiodarone and conventional therapy (93% ACE-inhibitors and/or ARBs, 90% betablockers, 93% diuretics) were enrolled. Mean arterial pressure (MAP), NYHA class, LVEF, calculated glomerular filtration rate (GFR), Na+, Haemoglobin, NT-proBNP, fT3, fT4 and TSH were evaluated. Patients with hyperthyroidism were excluded.
Results: During follow-up (24±10 months) 39 patients showed heart failure progression (26 were hospitalized, 4 underwent cardiac transplantation and 9 died after worsening of heart failure). Hypothyroidism (TSH >5.5 μU/ml) was observed in 20 (19%) patients, only in one with a concomitant reduction of fT3. The presence of hypothyroidism was associated to events at univariate (HR: 2.6, P: 0.006) as well as at multivariate Cox regression analysis (HR: 2.3, P: 0.035) after correcting for age, MAP, NYHA class, LVEF, GFR, Na+, Haemoglobin and NT-proBNP. Figure shows Kaplan-Meier curves for events in patients with and without hypothyroidism. In conclusion, our results suggest that in CHF patients with amiodarone therapy the detection of hypothyroidism, even the suclinical form, should be considered a marker of risk of heart failure progression. Further studies should also clarify the optimal therapeutical strategy in these patients: substitutive hormonal therapy and/or amiodarone withdrawal.
Prague, Czech Republic
24 - 28 Apr 2010
European Society of Endocrinology