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The risk of congestive heart failure but not other cardiovascular diseases is increased in subclinical hypothyroidism

(March 2006)

The background of the study. Subclinical hypothyroidism may have deleterious effects on cardiac function. In this study, the risk of heart failure and other cardiovascular disorders was determined in subjects with subclinical hypothyroidism.

How the study was done. The study subjects were 2730 people aged 70 to 79 years (51 percent women). At base line, serum thyrotropin (TSH) and free thyroxine were measured, and prevalent cardiovascular disease (coronary heart disease, stroke, peripheral arterial disease, and congestive heart failure) was diagnosed on the basis of the review of medical records.

The subjects were examined at six-month intervals for four years. Cardiovascular events, defined as death or hospitalization for coronary heart disease, stroke, peripheral arterial disease, and congestive heart failure, were determined from the patient’s records by clinicians unaware of the subject’s thyroid status.

The results of the study. At base line, 338 (12 percent) of the 2730 subjects had subclinical hypothyroidism. The prevalence of cardiovascular disease, including congestive heart failure, in the subjects with subclinical hypothyroidism and the normal two groups was similar.

During the four-year follow-up period, the frequency of congestive heart failure was slightly higher in the subjects with subclinical hypothyroidism than in the euthyroid subjects, whereas the frequency of coronary heart disease, stroke, and peripheral vascular disease was similar in the two groups. The mortality rates from cardiovascular disease and all causes were similar in the euthyroid subjects and the subjects with subclinical hypothyroidism.

The conclusions of the study. Among elderly subjects, subclinical hypothyroidism is associated with an increased frequency of congestive heart failure, but not coronary heart disease, stroke, or peripheral arterial disease.

The original article. Rodondi N, Newman AB, Vittinghoff E, de Rekeneire N, Satterfield S, Harris TB, Bauer DC. Subclinical hypothyroidism and the risk of heart failure, other cardiovascular events, and death. Arch Intern Med 2005;165:2460-6.

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