Radioiodine Treatment of Paroxysmal Supraventricular Tachycardia in the Euthyroid Patient

IN THE euthyroid patient, rapid supraventricular tachyeardias occur and are often resistant to prophylactic treatment with quinidine or pronestyl.' In an attempt to evaluate the effect of radioactive iodine in cases of supraventricular tachycardia resistant to antiarrhythmnic drugs, the authors treated 25 such patients with radioactive iodine and observed them for periods up to 6 years.2 In all instances prophylactic treatment with antiarrhythmic drugs had failed to prevent recurrent attacks. Twenty-two of these patients had arteriosclerotic heart disease and 3 had rheumatic heart disease. Manv of the patients had recurrent attacks as often as 4 times a day. In many instances, during the paroxysm oe tachycardia, the patient suffered severe anginal discomfort. All patients were considered euthyroid on the basis of clinical examination by 3 physicians and normal laboratory findings, including serum protein-bound iodine and radioactive iodine uptake. The patients with arteriosclerotic heart disease were selected from private practice. In these patients, the clinical history and the resting electrocardiogram or Master 2-step test revealed indications of coronary artery disease. The 3 patients with rheumatic heart disease all had multivalvular disease. The electrocardiographs during the episodes of tachyeardia revealed supraventricular rhythms.