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Major cardiac events are common after recovery from hyperthyroidism caused by amiodaronem
The background of the study. Hyperthyroidism is one well-known adverse effect of the antiarrhythmia drug amiodarone. In this study, the long-term outcome of patients with hyperthyroidism caused by amiodarone was determined.
How the study was done. The study subjects were 84 patients (average age, 60 years) who had hyperthyroidism during treatment with amiodarone for cardiac-rhythm disturbances. The patients’ records were reviewed, and surviving patients were interviewed. Particular attention was given to the patients’ symptoms, signs, and cardiac function, as determined by echocardiography, at the time of diagnosis of hyperthyroidism, and major cardiac events (myocardial infarction, heart failure, arrhythmia, stroke) and death after diagnosis and treatment of hyperthyroidism.
The results of the study. The average duration of amiodarone therapy at the time of diagnosis of hyperthyroidism was 31 months. The most common symptoms were weight loss, increased perspiration, palpitations, hyperactivity, and muscle weakness. Cardiac output at that time was 
50 percent of normal in 69 percent of patients and <50 percent in 31 percent of patients.
Most patients were treated with an antithyroid drug, prednisone, or both. The median times to normalization of serum free thyroxine and thyrotropin concentrations were 98 and 138 days, respectively, in the prednisone-treated patients and 108 and 141 days, respectively, in the antithyroid-drug–treated patients.
The median duration of follow-up after diagnosis of hyperthyroidism was 50 months, during which 19 percent died and 56 percent had major cardiac events. The mortality rate was similar in the patients with a normal left ventricular function and those with poor function, but the frequency of major cardiac events was higher in the patients with poor function.
The conclusions of the study. Amiodarone-associated hyperthyroidism usually occurs several years after initiation of the drug. The response to antithyroid drug or prednisone therapy is slow, and the long-term rates of major cardiac events and death are substantial.
The original article. Conen D, Melly L, Kaufmann C, Bilz S, Ammann P, Schaer B, Sticherling C, Muller B, Osswald S. Amiodarone-induced thyrotoxicosis: clinical course and predictors of outcome. J Am Coll Cardiol 2007;49:2350-5.
 Next Article: Blood-vessel inflammation and kidney disease can occur in patients with hyperthyroidism treated with propylthiouracil |
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| Thyroid Digest Index | | | November 2007 Thyroid Digest |
