Graves' disease and atrial fibrillation: the case for even higher doses of therapeutic iodine-131.

Seventy five consecutive patients with Graves' disease complicated by atrial fibrillation were given a large single therapeutic dose of 600 MBq (16.2 mCi) iodine-131 in an effort to control their hyperthyroidism rapidly and thus restore sinus rhythm. Patients were initially followed up every three months after treatment and then at yearly intervals. The mean period of follow up was 3.1 years. A total of 44 of the patients became hypothyroid and 31 euthyroid, and 33 (75%) and 14 (45%) of these patients, respectively, reverted to sinus rhythm (p less than 0.01). Of the 33 who became hypothyroid and reverted to sinus rhythm, 30 had developed the hypothyroidism within six months after treatment. These results are a strong case for increasing the dose of radioiodine in patients with Graves' disease complicated by atrial fibrillation in an effort to speed the onset of thyroid failure and thus maximise the rate of reversion to sinus rhythm.