Atrial fibrillation in thyrotoxicosis treated with radioiodine.

RADIOACTIVE Iodine (131I) is frequently recommended as the treatment of choice for thyrotoxicosis in patients over 45 years old without sufficient appreciation of the difficulties in management that occasionally occur. The increasing frequency of post-radiation myxoedema is now widely recognised (Green and Wilson, 1964) but less emphasis has been paid to the situation in some subjects in whom the first therapeutic dose may have little effect. Also little attention has been given to the management of a atrial filbrillation (A.F.) in thyrotoxicosis treated with 1311, though most of these cases are now treated by this method. This is in contrast to the interest shown by the surgical pioneers including Dunhill (1930) who considered that reversion of A.F. to normal rhythm was a good clinical index of the effectiveness of thyroidectomy. In this paper patients with A.F. and thyrotoxicosis who had been referred for 1311 treatment are reviewed with particular reference to reversion to sinus rhythm, the ultimate cardiac status and the risk of embolism.