[Subclinical hyperthyroidism and atrial fibrillation]

Atrial fibrillation (AF), the most widespread arrhythmia, is a source of disability and death in the elderly, in particular because of the functional heart failure entailed and the considerable frequency of thromboembolic complications. Today, overt hyperthyroidism (oHT) is generally believed to be the most important extracardiogenic predisposition factor for AF. There exists no widespread acceptance so far that subclinical hyperthroidism (sHT) influences the occurrence of AF. Furthermore, there are no clear recommendations for treatment of sHT to prevent AF. Recent data confirm AF prevalence to be 5-6 times higher not only in cases of oHT but also in sHT patients compared with a reference group with normal thyroid function. Subclinical hyperthyroidism increases the prevalence of AF approximately to the same extent as oHT and has to be included in diagnostical considerations in patients with AF.