Amiodarone-induced thyrotoxicosis: Should surgery be considered?

Amiodarone is the most widely prescribed antiarrhythmic drug worldwide, but induces thyrotoxicosis or hypothyroidism in 15 to 20% of patients. Hyperthyroidism is less frequent than hypothyroidism, and two types of thyrotoxicosis are distinguished according to presence of underlying thyroid disease. Diagnosis is made in case of low TSH and high levels of T3 and T4. Initial treatment is based on anti-thyroid drugs and/or glucocorticoids. Some patients do not respond to medication, which increases the time spent with hyperthyroidism. A long interval between diagnosis and euthyroidism and low left ventricular ejection fraction (LVEF) are predictive of major adverse cardiovascular events. Here, after describing the current state of knowledge of amiodarone-induced thyrotoxicosis, we analyze the literature on the impact of surgery. We suggest that early surgery should be the first option in case of ineffective medical treatment or LVEF<40%. In expert centers, surgical morbidity is no longer different than in other indications for thyroidectomy.

Mortality After Total Thyroidectomy for Amiodarone-Induced Thyrotoxicosis According to Left Ventricular Ejection Fraction.

OBJECTIVE: To report cardiac outcomes after total thyroidectomy for amiodarone-induced thyrotoxicosis according to the baseline left ventricular ejection fraction in a tertiary referral center. STUDY DESIGN: Retrospective, monocentric. SETTING: The tertiary health care system. METHODS: Patients who underwent total thyroidectomy for amiodarone-induced thyrotoxicosis between 2010 and 2020 with age >18 and available preoperative left ventricular ejection fraction were included in this study. Patients were dichotomized into: group 1 with left ventricular ejection fraction ≥40% (mildly reduced/normal ejection fraction), and group 2 with left ventricular ejection fraction <40% (reduced ejection fraction). RESULTS: There were 34 patients in group 1 and 17 to group 2. The latter were younger (median 58.4 [Q1-Q3 48.0-64.9] vs. 69.8 years in group 1 [59.8-78.3], p = .0035) and they presented more cardiomyopathy (58.8 vs. 26.5%, p = .030). Overall, the median time until surgery referral was 3.1 [1.9-7.1] months and 47.1% underwent surgery after restoration of euthyroidism. Surgical complications accounted for 7.8%. In group 2, the median left ventricular ejection fraction was significantly improved after surgery (22.5 [20.0-25.0] vs. 29.0% [25.3-45.5], p = .0078). Five-year cardiac mortality was significantly higher in group 2 (p < .0001): 47.0% died of cardiac causes versus 2.9% in group 1. A baseline left ventricular ejection fraction <40% and a longer time until surgery referral were significantly associated with cardiac mortality (multivariable Cox regression analysis, p = .015 and .020, respectively). CONCLUSION: These results reinforce the idea that surgery, if chosen, should be performed quickly in patients with left ventricular ejection fraction <40%.