![]() ![]() Iodothyronines have strong effects on cardiac function, including heart rhythm. Of note, up to a third of noncritically ill hospitalized patients may also demonstrate milder forms of NTIS. Results from clinical trials and animal experiments suggest possible favorable effects of TACITUS to be restricted to its acute phase, while chronic NTIS could represent a maladaptive response. Today it is still controversial as to whether NTIS represents a form of central hypothyroidism requiring treatment, whether it is simply associated with or results from severe illness, or if it represents an allostatic mechanism that is beneficial by reducing the demand for oxygen, energy and glutathione and by preventing the development of thyroid storm. ![]() It could not be proven, however, that therapy with T 4 or T 3 ameliorates the overall outcome of affected patients. Several trials have demonstrated improved surrogate parameters after substitution therapy with T 3 in NTIS. This condition is described as nonthyroidal illness syndrome (NTIS), euthyroid sick syndrome or TACITUS (thyroid allostasis in critical illness, tumors, uremia and starvation) and is accompanied by increased mortality and morbidity. diminished thyrotropin (TSH)-release despite decreased or low normal free thyroxine (FT 4) concentrations. More than 70% of critically ill patients develop a constellation that is marked by reduced concentrations of total (T) and free (F) 3,3′,5-triiodo- L-thyronine (T 3, low T 3 syndrome), impaired binding of thyroid hormones (TH) to their plasma proteins and, especially in chronic illness, by thyrotropic adaptation, i.e. The pathogenesis of NTIS therefore seems to involve more differentiated allostatic mechanisms. Conclusion: This study confirms reduced FT3 concentrations in patients with POAF and is the first to report on elevated 3,5-T2 concentrations in cardiac NTIS. In multivariable logistic regression FT3, 3,5-T2, total atrial conduction time, left atrial volume index and Fas ligand were independent predictors of POAF. Furthermore, 3,5-T2 concentrations were significantly elevated in patients with NTIS and in subjects who eventually developed POAF. 3,5-T2 concentrations directly correlated with rT3 concentrations and inversely correlated with FT3 concentrations. Results: Seven of 17 patients who developed POAF demonstrated nonthyroidal illness syndrome (NTIS defined as low T3 and/or low T4 syndrome), compared to 2 of 22 (p 3 concentrations were significantly decreased, but still within their reference ranges. Holter-ECG and telemetry were used to screen for POAF for 10 days following cardiac surgery. Serum concentrations of thyrotropin, free (F) and total (T) thyroxine (T4) and T3, reverse (r)T3, 3-iodothyronamine (3-T1AM) and 3,5-diiodothyronine (3,5-T2) were measured preoperatively, complemented by evaluation of echocardiographic and electrophysiological parameters of cardiac function. Methods: Thirty-nine patients with sinus rhythm and no history of atrial fibrillation or thyroid disease undergoing cardiac surgery were prospectively enrolled. This study reevaluates the relation between thyroid hormone status, atrial electromechanical function and POAF. Therapy with thyroid hormones (TH), however, did not reduce the risk of POAF. Background: Although hyperthyroidism predisposes to atrial fibrillation, previous trials have suggested decreased triiodothyronine (T3) concentrations to be associated with postoperative atrial fibrillation (POAF).
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