Subclinical Thyroid Dysfunction was not Associated with Cardiac Arrhythmias in a Cross-Sectional Analysis of the ELSA-Brasil Study

Abstract

Background The association of subclinical thyroid dysfunction (STD) with cardiac arrhythmias remains controversial, particularly in the non-elderly population. Objective To investigate whether STD was associated with cardiac arrhythmias in a cohort of middle-aged and older adults. Methods Baseline data of the Longitudinal Study of Adult Health, ELSA-Brasil (35-74 years) were collected from 2008 to 2010. After exclusion of clinical hypothyroidism and hyperthyroidism, participants were categorized as euthyroidism (TSH = 0.4-4.0 µ U/mL), subclinical hypothyroidism (TSH > 4.0 µ U/mL; FT4 = 0.8-1.9 ng/dL), and subclinical hyperthyroidism (TSH < 0.4 µ U/mL; FT4 = 0.8-1.9 ng/dL). The prevalence rates of tachycardia (HR > 100) and bradycardia (HR < 60), atrial fibrillation/flutter, conduction disorders, extrasystoles, low QRS voltage, prolonged QT intervals, and persistent supraventricular rhythms were compared between groups after adjusting for age, sex, comorbidities, lifestyle, body mass index and medications. Results The HR data of 13,341 participants (52% female; median age, 51 years) and the electrocardiogram readings of 11,795 were analyzed; 698 participants (5.23%) were classified as subclinical hypothyroidism, 193 (1.45%) as subclinical hyperthyroidism, and 12,450 (93.32%) as euthyroidism. The prevalence of rhythm and conduction disorders was similar, as were HR medians, even in the subgroups with TSH < 0.01 UI/mL or > 10.0 UI/mL or in older adults. Conduction disorders were less prevalent in older adults with subclinical hypothyroidism (adjusted OR = 0.44; 95% CI 0.24 to 0.80). Conclusion In this large, multicenter and cross-sectional study, STD was not associated with cardiac arrhythmias, but a longitudinal assessment is necessary.

State of the coronary arteries and assessment of the role of hormone replacement therapy in patients with coronary heart disease against the background of primary manifest hypothyroidism

“…Работы с более весомым объемом выборки не демонстрируют четких и определенных указаний в отношении положительного влияния L-тироксина на течение ИБС. По мнению исследователей, нет значимых различий в проявлении клинических симптомов (ангинозных приступов), в частоте развития новых случаев фибрилляции предсердий, а также других симпто-ОРИГИНАЛЬНЫЕ СТАТЬИ § мов ИБC по сравнению с пациентами, получавшими L-тироксин [17][18][19].…”