Permanent atrial fibrillation in heart failure patients as another condition with increased reverse triiodothyronine concentration.

ABSTRACT

OBJECTIVE: To fully investigate the thyroid hormonal function in patients with the most common arrhythmia - atrial fibrillation. MATERIALS AND METHODS: 120 patients (aged 55-85 yrs) with symptoms of congestive heart failure exacerbation and no other concomitant disorders (inclusion criteria normal cardiac troponin T at admission and 12 hours after, normal renal, hepatic and respiratory function; exclusion criteria inflammatory state, history of myocardial infarction). Depending on the presence of permanent atrial fibrillation (PAF), patients were divided into two groups PAF (34 females, 26 males) and regular sinus heart rhythm (43 females, 17 males), the groups did not differ in terms of heart rate, blood pressure, presence of overt/subclinical thyroid dysfunction, and medical therapy used. In all subjects thyroid stimulating hormone, free thyroxine, free triiodothyronine, reverse triiodothyronine were measured; echocardiography was performed. RESULTS: PAF group showed higher FT4 and rT3 (1.41 vs. 1.27 ng/dl, p=0.0007; 0.61 vs. 0.32 ng/ml, p<0.0001, respectively). With ROC curve analysis the biochemical thyroid related factor of the highest prognostic value for PAF occurrence (with the highest sensitivity and specificity 77% and 72%, respectively) was rT3 with the cut-off of above 0.3 ng/ml. Also, a positive correlation between rT3 levels and left ventricular posterior wall diameter was observed (Spearman's correlation coefficient 0.33, p=0.0093). CONCLUSIONS: PAF is another condition where an increase in rT3 is observed. rT3 concentration above 0.3 ng/ml may be a novel biochemical sign associated with the presence of PAF in patients with chronic heart failure.