Endocrine Abstracts

Introduction: Atrial fibrillation (AF) is the most common cardiac complication of hyperthyroidism, with significant mortality and morbidity resulting from embolic events. In patients who attend at an emergency room (ER) with acute AF, the thyroid hormones aren’t usually evaluated given the low prevalence of hyperthyroidism in the general population.

Aims: To assess the prevalence of thyroid dysfunction in adult patients who presented at an ER with acute AF.

Methods: Prospective study of consecutive patients with acute AF that attended our hospital’s ER; excluded those with hypothalamic or pituitary disease, pregnancy, corticosteroid or dopamine therapy, hemodynamic instability. Selected as controls patients in sinus rhythm who presented at the ER on the same period of time. All patients answered a brief questionnaire (age, medications in use, medical history, saline restriction), underwent clinical examination, electrocardiogram and blood samples for thyroid function tests. Those with an altered serum TSH level were subsequently reevaluated for confirmation of thyroid dysfunction.

Results: Total of 105 individuals, 61 patients (acute AF) and 44 controls (sinus rhythm). Cases had a higher prevalence of thyroid dysfunction (37.7% vs 9.1%, P=0.001), total hyperthyroidism (24.6% vs 2.3%, P=0.002), overt (14.8% vs 0%, P=0.008) and subclinical hyperthyroidism (9.8% vs 2.3%, P=n.s.). There was a negative correlation between serum TSH levels and heart frequency of the arrhythmia (ρ=−0.36, P=0.004) and also between serum TSH levels and the number of anti-arrhythmic drugs necessary for treatment (ρ=−0.313, P=0.014). The odds-ratio of an acute AF patient having hyperthyroidism was 14.02.

Conclusions: The high prevalence of hyperthyroidism in patients with acute AF attended at our ER suggests that routine thyroid testing is required. Serum TSH level negatively correlates with heart frequency, emphasizing the importance of thyroid function in conversion to sinus rhythm.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.