@article {890, title = {Thyroid status, cardiovascular risk, and mortality in older adults.}, journal = {JAMA}, volume = {295}, year = {2006}, month = {2006 Mar 01}, pages = {1033-41}, abstract = {

CONTEXT: Previous studies have suggested that subclinical abnormalities in thyroid-stimulating hormone levels are associated with detrimental effects on the cardiovascular system.

OBJECTIVE: To determine the relationship between baseline thyroid status and incident atrial fibrillation, incident cardiovascular disease, and mortality in older men and women not taking thyroid medication.

DESIGN, SETTING, AND PARTICIPANTS: A total of 3233 US community-dwelling individuals aged 65 years or older with baseline serum thyroid-stimulating hormone levels were enrolled in 1989-1990 in the Cardiovascular Health Study, a large, prospective cohort study.

MAIN OUTCOME MEASURES: Incident atrial fibrillation, coronary heart disease, cerebrovascular disease, cardiovascular death, and all-cause death assessed through June 2002. Analyses are reported for 4 groups defined according to thyroid function test results: subclinical hyperthyroidism, euthyroidism, subclinical hypothyroidism, and overt hypothyroidism.

RESULTS: Individuals with overt thyrotoxicosis (n = 4) were excluded because of small numbers. Eighty-two percent of participants (n = 2639) had normal thyroid function, 15\% (n = 496) had subclinical hypothyroidism, 1.6\% (n = 51) had overt hypothyroidism, and 1.5\% (n = 47) had subclinical hyperthyroidism. After exclusion of those with prevalent atrial fibrillation, individuals with subclinical hyperthyroidism had a greater incidence of atrial fibrillation compared with those with normal thyroid function (67 events vs 31 events per 1000 person-years; adjusted hazard ratio, 1.98; 95\% confidence interval, 1.29-3.03). No differences were seen between the subclinical hyperthyroidism group and euthyroidism group for incident coronary heart disease, cerebrovascular disease, cardiovascular death, or all-cause death. Likewise, there were no differences between the subclinical hypothyroidism or overt hypothyroidism groups and the euthyroidism group for cardiovascular outcomes or mortality. Specifically, individuals with subclinical hypothyroidism had an adjusted hazard ratio of 1.07 (95\% confidence interval, 0.90-1.28) for incident coronary heart disease.

CONCLUSION: Our data show an association between subclinical hyperthyroidism and development of atrial fibrillation but do not support the hypothesis that unrecognized subclinical hyperthyroidism or subclinical hypothyroidism is associated with other cardiovascular disorders or mortality.

}, keywords = {Aged, Atrial Fibrillation, Cardiovascular Diseases, Female, Humans, Hyperthyroidism, Hypothyroidism, Male, Proportional Hazards Models, Risk Factors, Thyroid Gland, Thyrotropin}, issn = {1538-3598}, doi = {10.1001/jama.295.9.1033}, author = {Cappola, Anne R and Fried, Linda P and Arnold, Alice M and Danese, Mark D and Kuller, Lewis H and Burke, Gregory L and Tracy, Russell P and Ladenson, Paul W} } @article {1053, title = {Subclinical thyroid dysfunction, cardiac function, and the risk of heart failure. The Cardiovascular Health study.}, journal = {J Am Coll Cardiol}, volume = {52}, year = {2008}, month = {2008 Sep 30}, pages = {1152-9}, abstract = {

OBJECTIVES: The goal of this study was to determine whether subclinical thyroid dysfunction was associated with incident heart failure (HF) and echocardiogram abnormalities.

BACKGROUND: Subclinical hypothyroidism and hyperthyroidism have been associated with cardiac dysfunction. However, long-term data on the risk of HF are limited.

METHODS: We studied 3,044 adults>or=65 years of age who initially were free of HF in the Cardiovascular Health Study. We compared adjudicated HF events over a mean 12-year follow-up and changes in cardiac function over the course of 5 years among euthyroid participants, those with subclinical hypothyroidism (subdivided by thyroid-stimulating hormone [TSH] levels: 4.5 to 9.9, >or=10.0 mU/l), and those with subclinical hyperthyroidism.

RESULTS: Over the course of 12 years, 736 participants developed HF events. Participants with TSH>or=10.0 mU/l had a greater incidence of HF compared with euthyroid participants (41.7 vs. 22.9 per 1,000 person years, p=0.01; adjusted hazard ratio: 1.88; 95\% confidence interval: 1.05 to 3.34). Baseline peak E velocity, which is an echocardiographic measurement of diastolic function associated with incident HF in the CHS cohort, was greater in those patients with TSH>or=10.0 mU/l compared with euthyroid participants (0.80 m/s vs. 0.72 m/s, p=0.002). Over the course of 5 years, left ventricular mass increased among those with TSH>or=10.0 mU/l, but other echocardiographic measurements were unchanged. Those patients with TSH 4.5 to 9.9 mU/l or with subclinical hyperthyroidism had no increase in risk of HF.

CONCLUSIONS: Compared with euthyroid older adults, those adults with TSH>or=10.0 mU/l have a moderately increased risk of HF and alterations in cardiac function but not older adults with TSH<10.0 mU/l. Clinical trials should assess whether the risk of HF might be ameliorated by thyroxine replacement in individuals with TSH>or=10.0 mU/l.

}, keywords = {Aged, Aged, 80 and over, Cohort Studies, Echocardiography, Female, Heart, Heart Failure, Heart Function Tests, Humans, Hyperthyroidism, Hypertrophy, Left Ventricular, Hypothyroidism, Male, Risk Factors, Time Factors}, issn = {1558-3597}, doi = {10.1016/j.jacc.2008.07.009}, author = {Rodondi, Nicolas and Bauer, Douglas C and Cappola, Anne R and Cornuz, Jacques and Robbins, John and Fried, Linda P and Ladenson, Paul W and Vittinghoff, Eric and Gottdiener, John S and Newman, Anne B} }