In the treatment of the thyrotoxic heart a radical, early thyroeliminating procedure should have preference. As the method of first choice a single administration of a whole calculated dose of I 131 is recommended without previous medicamentous preparation up to 25-30 mCie which can be administered also in the out-patient department, with subsequent immediate treatment with thyrostatics and beta-blockers till remission of thyrotoxicosis is achieved (6-12 weeks). Total strumectomy after medicamentous preparation in remission of thyrotoxicosis is preferred in large multinodular, iodinated patients and in solitary toxic adenoma where however also partial STE (lobectomy) is possible and radioiodine is equivalent. Its dosage in toxic adenoma and nodular goitre is however in general higher than in diffuse goitre but the incidence of late postadministration hypothyroidism is lower. Fibrillation arythmia usually (in ca 60%) recedes spontaneously with the assistance of beta-blockers in remission of thyrotoxicosis. If this does not occur, pharmacological or electric cardioversion is necessary after anticoagulation preparation, because persistence of FA is an important risk factor of cardiac failure and thromboembolic complications. Eurhythmia then usually lasts as long as remission of thyrotoxicosis persists or there is no overdosage of substitution doses of T4 during treatment of hypothyroidism which develops after thyroelimination treatment. Amiodarone is unsuitable, even contraindicated, for treatment of fibrillation arythmia in thyrotoxic heart.

        Key words: Thyrotoxic heart - Medicamentous treatment - Surgical treatment - Radioiodine treatment