Subclinical thyroid dysfunction, cardiac function, and the risk of heart failure. The Cardiovascular Health study.
OBJECTIVE
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.
Rodondi
Nicolas
N
Department of Ambulatory Care and Community Medicine, University of Lausanne, Lausanne, Switzerland. Nicolas.Rodondi@hospvd.ch
Bauer
Douglas C
DC
Cappola
Anne R
AR
Cornuz
Jacques
J
Robbins
John
J
Fried
Linda P
LP
Ladenson
Paul W
PW
Vittinghoff
Eric
E
Gottdiener
John S
JS
Newman
Anne B
AB
D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000209:etiology* / Q000503:physiopathology; D006334:Heart Function Tests; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications* / Q000503:physiopathology; D017379:Hypertrophy, Left Ventricular / Q000209:etiology; D007037:Hypothyroidism / Q000150:complications* / Q000503:physiopathology; D008297:Male; D012307:Risk Factors; D013997:Time Factors