Amiodarone-associated thyroid dysfunction - Risk factors in adults with congenital heart disease

Background-Amiodarone is widely used in adults with congenital heart diseas e, but no systematic study has been published on its effects on thyroid fun ction in these patients. A retrospective study was performed to examine the frequency of amiodarone-associated thyroid dysfunction in adults with cong enital heart disease and to identify any contributing factors. Methods and Results-All adults (16 to 60:years old) with congenital heart d isease were identified from a database if they had no preexisting thyroid d isease, had taken amiodarone for greater than or equal to 6 months, and wer e currently followed up by 1 consultant (J.S.), Ninety-two patients were fo und and evaluated for thyroid status and cardiac complications. A case-cont rol analysis was performed, with patients matched for duration of amiodaron e therapy. Of the 92 patients (age, 34.9+/-10.2 years; range, 18 to 60 year s), 36% developed thyroid dysfunction: 19 became hyperthyroid and 14 hypoth yroid. Female sex and complex cyanotic heart disease were significant risk factors for developing thyroid dysfunction (odds ratios, 3.0 and 7.00; P=0. 04 and 0.01, respectively). Previous Fontan-type surgery also appeared to b e a risk factor for developing thyrotoxicosis (odds ratio, 4.0; P=0.17), an d amiodarone >200 mg/d a risk factor for thyroid dysfunction (odds ratio, 4 .0; P=0.60). Conclusions-Amiodarone-associated thyroid dysfunction is common in adults w ith congenital heart disease. Women and those with complex cyanotic lesions are at particular risk, as patients may be who have had Fontan-type surger y or are taking >200 mg/d of amiodarone. Amiodarone should be used only whe n other antiarrhythmics are ineffective or contraindicated. Vigilance is re quired to detect and treat thyroid dysfunction.