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High-normal thyroid function and risk of atrial fibrillation: the Rotterdam study
Jan Heeringa1, E H Hoogendoorn, W M van der Deure
1Department of Epidemiology and Biostatistics, Erasmus Medical Center, Rotterdam, the Netherlands.
Archives of Internal Medicine
|November 13, 2008
Summary
High-normal thyroid function increases atrial fibrillation risk in the elderly. Even within normal ranges, thyroid hormone levels impact heart rhythm, highlighting the need for careful monitoring.
Area of Science:
- Endocrinology
- Cardiology
- Geriatrics
Background:
- Overt and subclinical hyperthyroidism are established risk factors for atrial fibrillation.
- The association between high-normal thyroid function and atrial fibrillation in the elderly remains less understood.
Purpose of the Study:
- To investigate the link between high-normal thyroid function and the incidence of atrial fibrillation in an elderly population.
- To determine if thyroid-stimulating hormone (TSH) and free thyroxine levels within the normal range predict atrial fibrillation development.
Main Methods:
- Prospective population-based study involving 1426 elderly individuals without atrial fibrillation at baseline.
- Analysis of thyroid-stimulating hormone (TSH) and free thyroxine levels within normal ranges.
- Cox proportional hazards models were used to calculate adjusted hazard ratios for atrial fibrillation development over an 8-year median follow-up.
Main Results:
- A significant association was found between thyroid-stimulating hormone (TSH) levels and the risk of atrial fibrillation (adjusted HR 1.94; P for trend .02).
- Higher levels of free thyroxine within the normal range showed a trend towards increased atrial fibrillation risk (adjusted HR 1.62; P for trend .06).
Conclusions:
- Within the normal spectrum of thyroid function, individuals with high-normal thyroid parameters face an elevated risk of developing atrial fibrillation.
- These findings suggest that thyroid function within the high-normal range may be a significant, previously underappreciated, risk factor for atrial fibrillation in the elderly.
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