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Cardiovascular abnormalities improve with treatment in patients with hyperthyroidism
The background of the study. Hyperthyroidism has multiple effects on cardiovascular function. In this study, cardiovascular symptoms and function were determined in patients with hyperthyroidism and then during or after treatment when they had subclinical hyperthyroidism and when they were euthyroid.
How the study was done. The study subjects were 393 patients with overt hyperthyroidism and 393 age- and sex-matched control subjects; their mean age was 49 years. The patients were studied before treatment (an antithyroid drug, radioactive iodine, or both), and again during or after treatment. At the time of the second study, 110 patients had subclinical hyperthyroidism (mean interval, 27 weeks) and 207 were euthyroid (mean interval, 37 weeks). Each study included a systematic evaluation of cardiovascular symptoms and signs, electrocardiography (ECG), and in many, 24-hour Holter monitoring.
The results of the study. More patients than control subjects had symptoms and signs of cardiovascular dysfunction, such as palpitations, chest pain, shortness of breath, and rapid heart rate. The resting pulse rate, ECG, and 24-hour monitoring results were more often abnormal in the patients with hyperthyroidism (Table). As compared with the control subjects, most of the symptoms and some of the hemodynamic and monitoring abnormalities were no longer present in the patients with subclinical hyperthyroidism, and there were no differences in those studied when they were euthyroid.
Table. Electrocardiographic and Monitoring Findings in Patients with Hyperthyroidism and Control Subjects. |
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|
Patients (n = 392) |
Control Subjects (n = 392) |
Resting pulse rate (beats/min) |
82 |
73 |
Supine systolic blood pressure (mm Hg) |
137 |
129 |
Atrial fibrillation (ECG) |
24 (6%) |
3 (1%) |
24-hour monitoring (n = 311) |
|
|
Maximum heart rate (beats/min) |
128 |
122 |
Atrial fibrillation |
22 (7%) |
4 (1%) |
The conclusions of the study. Cardiovascular symptoms and heart-rate abnormalities are more common in patients with hyperthyroidism than in control subjects. The abnormalities become less frequent with transition from overt hyperthyroidism to subclinical hyperthyroidism to normal thyroid function.
The original article. Osman F, Franklyn JA, Holder RL, Sheppard MC, Gammage MD. Cardiovascular manifestations of hyperthyroidism before and after antithyroid therapy: a matched case-control study. J Am Coll Cardiol 2007;49:71-81.
Next Article: Serum thyrotropin-receptor and antithyroid peroxidase antibodies change differently during treatment of patients with hyperthyroidism caused by Graves’ disease |
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| Thyroid Digest Index | | | March 2007 Thyroid Digest |
