Clinical Research
Heart Failure
Subclinical Thyroid Dysfunction, Cardiac Function, and the Risk of Heart Failure: The Cardiovascular Health Study

https://doi.org/10.1016/j.jacc.2008.07.009Get rights and content
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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 ≥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, ≥10.0 mU/l), and those with subclinical hyperthyroidism.

Results

Over the course of 12 years, 736 participants developed HF events. Participants with TSH ≥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 ≥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 ≥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 ≥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 ≥10.0 mU/l.

Key Words

subclinical thyroid dysfunction
heart failure
echocardiography
cohort study

Abbreviations and Acronyms

CHS
Cardiovascular Health Study
CI
confidence interval
CVD
cardiovascular disease
FT4
free thyroxine
HF
heart failure
HR
hazard ratio
LV
left ventricular
RCT
randomized controlled trial
TSH
thyroid-stimulating hormone

Cited by (0)

The research reported in this article was supported by contracts N01-HC-35129, N01-HC-45133, N01-HC-75150, N01-HC-85079 through N01-HC-85086, N01 HC-15103, N01 HC-55222, and U01 HL080295 from the National Heart, Lung, and Blood Institute (NHLBI), with additional contribution from the National Institute of Neurological Disorders and Stroke. A full list of participating CHS investigators and institutions can be found at http://www.chs-nhlbi.org. The TSH measurement and this study were supported by an American Heart Association Grant-in-Aid (to Dr. Fried) with funding from July 1991 to June 1993. This study was funded through contracts with the NHLBI and included substantial NHLBI involvement in study design and oversight. A member of the NHLBI serves on the executive committee of the study, and the NHLBI reviewed the manuscript and approved its publication.