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Congestive heart failure is rare in hyperthyroidism, and when present is associated with atrial fibrillation
The background of the study. Patients with hyperthyroidism may have cardiovascular dysfunction, including occasionally congestive heart failure. In this study, the prevalence, risk factors, characteristics, and outcome of congestive heart failure in a large group of patients with hyperthyroidism were determined.
How the study was done. The study subjects were 591 patients (451 women, 140 men; averge age, 45 years) with hyperthyroidism caused by Graves’ disease or toxic multinodular goiter. The diagnosis of congestive heart failure was based on the presence of symptoms and signs of circulatory overload, including shortness of breath with exertion or when lying flat, fluid in the lungs, enlargement of the heart, rapid or irregular heart rate, and enlargement of the liver.
The results of the study. Thirty-four patients (6 percent) had congestive heart failure. They differed in several respects from the other 557 patients, especially in the frequency of the cardiac rhythm disorder known as atrial fibrillation (Table), but not in the frequency of Graves’ disease or toxic multinodular goiter or in serum free thyroxine values.
| Table. Characteristics of 591 Patients with Hyperthyroidism with or without Congestive Heart Failure. | ||
Heart Failure (n = 34) |
No Heart Failure (n = 557) |
|
| Women/men | 14/20 |
437/120 |
| Mean age (yr) | 66 |
44 |
| Hypertension | 11 (32%) |
39 (7%) |
| Mean duration of symptoms (days) | 39 |
32 |
| Mean heart rate (bpm) | 138 |
100 |
| Atrial fibrillation | 32 (94%) |
50 (9%) |
The patients were treated with an antithyroid drug or radioactive iodine. Approximately 50 percent of the patients with atrial fibrillation had a normal cardiac rhythm 3 to 12 months later.
The conclusions of the study. Congestive heart failure is rare in patients with hyperthyroidism, and when present is associated with atrial fibrillation.
The original article. Siu CW, Yeung CY, Lau CP, Kung AW, Tse HF. Incidence, clinical characteristics and outcome of congestive heart failure as the initial presentation in patients with primary hyperthyroidism. Heart 2007;93:483-7.
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| Thyroid Digest Index | | | July 2007 Thyroid Digest |
