ElectophysiologySubclinical hyperthyroidism as a risk factor for atrial fibrillation☆
Section snippets
Population
From January 1986 to August 1995, we studied 1338 consecutive patients with low serum thyrotropin concentrations examined at our institution. The underlying thyroid disease was functional autonomy in 85% of the cases and immunogenic thyreopathy in 15%.
The control group (group 1) contained 22,300 euthyroid people ≥45 years old who were admitted to our institution from January 1989 to December 1994.
The entire group of persons with low serum thyrotropin concentrations comprised 725 patients with
Prevalence of atrial fibrillation
Atrial fibrillation was detected in 178 persons with low thyrotropin levels. One hundred patients (13.8%) in group 2 (overt hyperthyroidism) and 78 (12.7%) in group 3 (subclinical hyperthyroidism) had atrial fibrillation. In contrast, atrial fibrillation was present in 513 persons in group 1 with normal values for serum thyrotropin.
The prevalence of atrial fibrillation in patients with low serum thyrotropin concentrations (<0.4 mU/L) was 13.3% compared with 2.3% in patients with normal values
Discussion
Many patients with thyrotoxicosis have clinical features that reflect the effects of excess thyroid hormone on the cardiovascular system. Thyrotoxicosis can aggravate pre-existing cardiac disease and can also lead to atrial fibrillation, congestive heart failure, or worsening of angina pectoris. In elderly patients, these cardiac manifestations may dominate the clinical picture and warrant the measurement of the serum thyrotropin concentration. In the absence of pre-existing cardiac disease,
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Reprint requests: Johann Auer, MD, IInd Medical Department, Division of Cardiology and Intensive Care, General Hospital Wels, Grieskirchnerstraße 42, 4600 Wels, Austria. E-mail: [email protected]