methimazole and Tachycardia--Ventricular

We report a case of amiodarone-induced thyrotoxicosis, and a broad review of the literature. Amiodarone is a drug widely used in cardiovascular medicine. Since it is iodine-rich, it may cause changes in thyroid function tests in some patients under chronic treatment. In 14-18% of amiodarone-treated patients, there is overt thyroid dysfunction (hypothyroidism or thyrotoxicosis). We here describe thyrotoxicosis, which can be distinguished in two subtypes differing in pathogenesis and treatment. Type I is primarily related to an excess of iodine-induced thyroid hormone synthesis in an abnormal thyroid gland, and the main medical treatment consists of the simultaneous administration of thionamides and potassium perchlorate. Type II is due to amiodarone-related destructive thyroiditis and glucocorticoids are therapy of choice. Mixed forms frequently exist. Due to the low thyroidal iodine uptake, radioiodine therapy is usually not efficacious. Surgical treatment can be performed in cases resistant to medical therapy.

Topics: Adult; Amiodarone; Anti-Arrhythmia Agents; Antithyroid Agents; Cardiomyopathy, Hypertrophic, Familial; Humans; Male; Methimazole; Tachycardia, Ventricular; Thyrotoxicosis; Treatment Outcome

Topics: Adult; Bisoprolol; Electrocardiography; Female; Humans; Methimazole; Prednisolone; Tachycardia, Ventricular; Thyroiditis, Subacute

Monomorphic ventricular tachycardia (VT) is a unique manifestation of hyperthyroidism. We present the case of a 41-year-old male with a history of hyperthyroidism presenting with palpitations secondary to non-sustained episodes of monomorphic VT. Cardiac arrhythmias due to thyrotoxicosis are perpetually supraventricular in origin. Monomorphic VT in the setting of thyrotoxicosis in the absence of structural heart disease is exceedingly rare. After starting propranolol and increasing the dose of methimazole, the patient had no further episodes of VT. It is important to recognize repetitive monomorphic VT as an understated but important manifestation of thyrotoxicosis. Propranolol is associated with an excellent response in these patients and anti-thyroid medications such as methimazole effectively reverse thyrotoxicity.

Topics: Adrenergic beta-Antagonists; Adult; Antithyroid Agents; Humans; Male; Methimazole; Propranolol; Tachycardia, Ventricular; Thyrotoxicosis