Introduction: The hyperthyroidism is a risk factor for tachyarrhythmia and dilated cardiomyopathy. Amiodarone is an effective antiarrhythmic medication, however if coexisting thyroid pathology complicates the treatment of thyroid dysfunction. It presents a case of Graves disease (GD) of long evolution, which illustrates the complexity of these associations. Clinical case: man, 44 years old, smoker, history of acute myocardial infarction and GD diagnosed at age 28. Has made treatment with propylthiouracil during 3 years, having abandoned the medical follow-up. Admitted for urgent care by signs and symptoms of hyperthyroidism and heart failure (class IV NYHA), with 1 month of evolution. He presented with tachyarrhythmia, tremor, visible and palpable diffuse goiter, slight active Graves ophthalmopathy. Eletrocardiogram: ventricular tachycardia alternating with sinus rhythm, left anterior hemiblock, repolarization changes suggesting ischemia. Echocardiography:dilated ischemic heart disease, LVEF-32%, suspicion of intracavitary thrombus in the left ventricle. Laboratory tests: TSH<0.003 μU/ml; fT4 2.18 ng/dl (0.71.48); fT3 6.06 pg/ml (1.713.71); anti-TPO 514 UI/ml; anti-Tg 18.9 UI/ml; TRAb 12.4 UI/ml; pro-BNP 2146 pg/ml; troponina 33.8 ng/l (<15). Cervical ultrasound revealed GD. Established therapy in hospital:amiodarone, rivaroxaban, atorvastatin, furosemide, ramipril, spironolactone, bisoprolol, thiamazol and prednisolone. There was clinical improvement and normalization of thyroid function. It was decided to thyroidectomy about 2 weeks after the episode. After 6 months: Echocardiography: LVEF-55%, segmental hypokinesia; Coronary angiography: LVEF 60%, occluded coronary proximal left anterior descending, filling by collateral of the right coronary artery. Performed coronary artery bypass surgery.
Discussion: The effect of hyperthyroidism in the myocardium begins to be better understood. The euthyroid state allows the improvement/reversion of cardiac abnormalities. The amiodarone is effective, even in the context of thyrotoxicosis, contributing to normalization of thyroid hormones (Wolf-Chaikoff effect). However, in the long term may worsen the hyperthyroidism by escape of this mechanism. Thus, thyroidectomy in the short term is the best definitive treatment of the GD, being carried out without major surgical risk, when normalized thyroid hormones.