Atrial fibrillation and hyperthyroidism: a new look at their relationship and therapy with lidoflazine.

Various kinds of dysrhythmias are found in association with hyperthyroidism but especially atrial fibrillation. The causal relationship of chronic atrial fibrillation and the endocrine disorder is controversial, as is its therapeutic management. Six patients with this particular combination of disorders were treated with lidoflazine: a new anti-anginal drug with anti-arrhythmic activity. All six patients returned to sinus rhythm on lidoflazine treatment although still hyperthyroid and remained in sinus rhythm during the follow up period ranging from 5 to 14 months. This occurred independently of antithyroid treatment. Some evidence is put forward that dysrhythmias and most commonly chronic atrial fibrillation are triggered off by hyperthyroidism or other disorders but that they are maintained by permanent cardiac damage due to arteriosclerosis, hypertension, coronary heart disease or rheumatic valve disease. Successful chemical cardioversions and maintenance of sinus rhythm can be obtained independent of the thyroid function. Our results confirm the anti-arrhythmic activity of lidoflazine.