Thyroidectomy for Amiodarone-Induced Thyrotoxicosis: Mayo Clinic Experience

Life-threatening amiodarone-induced thyrotoxicosis - Personalized approach to radical treatment

Objective

Amiodarone is an iodine-rich molecule and an effective antiarrhythmic drug. It is a first-line treatment for patients with life-threatening ventricular arrhythmias and for prevention in patients at high risk. The use of amiodarone may cause serious adverse effects such as pharmacotherapy-resistant, life-threatening amiodarone-induced thyrotoxicosis (AIT)leading to rapid deterioration of the patient's condition.According to the European Thyroid Association (ETA) guidelines, emergency thyroidectomy is the first-line treatment option in these cases. ; however, is not always feasible in the clinical setting due to the high anesthetic risk.We aimed to assess the clinical course and results of urgent thyroidectomy and 131-I therapy in patients with severe AIT with worsening of cardiac status.

Methods

Retrospective analysis of the clinical course and outcomes of life-threatening AIT refractory to pharmacotherapy in patients hospitalized at a tertiary endocrinology center between 2014 and 2022.

Results

An electronic database search identified 75 patients hospitalized for severe AIT. At the time of AIT diagnosis, median Thyroid-stimulating hormone (TSH) concentration was 0.001 mIU/L (range 0.001-0.35), fT4 63.2 pmol/L (range 9.0 - >100), and fT3 10.2 pmol/L (range 3.8-49.3). All patients received optimal conservative treatment. Among them, 20 required urgent radical therapy due to worsening arrhythmias and/or AIT-related heart failure. In this group, 6 patients died before any radical treatment was applied, 6 underwent total thyroidectomy, while 8 patients were successfully treated with 131-I (in 6 cases after rhTSH stimulation). The median dose of 131-I used for the therapy was 784MBq (range 627-860). The decision to treat with 131-I despite low but detectable 131-I uptake (median value 6 %) was made in cases of significant contraindications to anesthesia due to refractory ventricular arrhythmias, exacerbation of severe heart failure unresponsive to cardiac treatment, myocardial infarction during AIT course, massive pulmonary embolism.

Conclusion

The decision regarding the optimal time and type of radical treatment of AIT refractory to pharmacotherapy is critical for patients management and should not be delayed. Urgent therapy with 131-I may be an effective therapeutic option in patients who are unsuitable for thyroidectomy due to the high risk of anesthesia.

A Case of Amiodarone-Induced Thyrotoxicosis Presenting With Methimazole-Induced Agranulocytosis

Amiodarone is a class III anti-arrhythmic drug found to be effective in treating multiple life-threatening arrhythmias, including paroxysmal atrial fibrillation. Despite its effectiveness, amiodarone has been found to result in thyroid dysfunction. Amiodarone-induced thyrotoxicosis (AIT) is classified as type 1, which often develops in those with autoimmune hyperthyroid conditions, or type 2, which occurs because of destructive thyroiditis in an apparently normal thyroid. Differentiating between both types often poses a clinical and therapeutic dilemma, as AIT 1 is treated with thionamides, whereas AIT 2 requires steroids for treatment. We present a case of a patient with AIT who was treated empirically for both subtypes with methimazole and prednisone without clinical improvement. Methimazole was later stopped due to concern for agranulocytosis, and the patient was then treated with cholestyramine, metoprolol, and prednisone. Given persistent thyrotoxicosis, the decision was made to proceed with surgical intervention. The patient underwent a successful total thyroidectomy without complications. The patient's condition clinically improved post-surgery and was discharged home on post-operative day 2 in stable condition. Prednisone was tapered over two weeks, and he was started on a weight-based dose of levothyroxine. He continues to follow up in our clinic for postoperative hypothyroidism and is clinically and biochemically euthyroid.

Cardiac evaluation in amiodarone-induced thyroid dysfunction with suspected cardiac ischemia?: a case report and review of the literature

BACKGROUND

Amiodarone-induced thyroid dysfunction (AIT) is a side-effect associated with the use of Amiodarone for the treatment of refractory arrythmias. Resulting hyperthyroidism can precipitate cardiac complications, including cardiac ischemia and myocardial infarction, although this has only been described in a few case reports.

CASE PRESENTATION

We present here a clinical scenario involving a 66-year-old male Caucasian patient under Amiodarone for atrial fibrillation, who developed AIT. In the presence of dyspnea, multiple cardiovascular risk factors and ECG abnormalities, a transthoracic echocardiogram was performed, showing inferobasal hypokinesia. This led to further investigations through a cardiac PET-CT, where cardiac ischemia was suspected. Ultimately, the coronary angiography revealed no abnormalities. Nonetheless, these extensive cardiologic investigations led to a delay in initiating an emergency endovascular revascularization for acute-on-chronic left limb ischemia. Although initial treatment using Carbimazole was not successful after three weeks, the patient reached euthyroidism after completion of the treatment with Prednisone so that eventually thyroidectomy was not performed. Endovascular revascularization was finally performed after more than one month.

CONCLUSIONS

We discuss here cardiac abnormalities in patients with AIT, which may be due to relative ischemia secondary to increased metabolic demand during hyperthyroidism. Improvement of cardiac complications is expected through an optimal AIT therapy including medical therapy as the primary approach and, when necessary, thyroidectomy. Cardiac investigations in the context of AIT should be carefully considered and may not justify delaying other crucial interventions. If considered mandatory, diagnostic procedures such as coronary angiography should be preferred to functional testing.

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.

The roles of thyroidectomy in patients with amiodarone-induced thyrotoxicosis: A systematic review

The principal management of Amiodarone-induced-thyrotoxicosis (AIT) is balancing cardiac-thyroid conditions. However, the role of thyroidectomy is still contentious. This systematic review aims to provide insights into the roles of thyroidectomy in the management of AIT. This systematic review encompasses 303 AIT patients who underwent thyroidectomy from 14 studies. The indication of thyroidectomy can be due to cardiac factors, thyrotoxicosis conditions, and patient-physician considerations. Thyroidectomy is more effective in improving thyroid hormone status, cardiac function, and mortality compared to optimal medical therapy, especially in those with left ventricular ejection fraction < 40 %. Thyroidectomy is effective in improving cardiac function and mortality due to shorter duration for achieving euthyroid. Thyroidectomy and medical therapy have comparable side effects. However, the identification of high-risk patients may reduce thyroidectomy complications. Thus, thyroidectomy should not be viewed as the last resource and should be performed immediately when indicated.

Short review: novel concepts in the approach to patients with amiodarone-induced thyrotoxicosis

INTRODUCTION

Amiodarone-induced thyrotoxicosis is associated with high morbidity and mortality rates. The approach to this condition is widely variable across different medical specialists and even among expert endocrinologists. As a matter of fact, the approach to amiodarone-induced thyrotoxicosis has always been considered difficult, due to diagnostic uncertainties easily resulting in missteps, and therapeutic challenges easily resulting in unresponsiveness or slow-responsiveness to the administered drugs.

PURPOSE

Our purpose is to review novelties emerged during the last years about this condition, with the aim to provide novel insights on the diagnostic and therapeutic management of this challenging condition.

Monitoring thyroid function during amiodarone use

Amiodarone is an antiarrhythmic drug used to treat cardiac tachyarrhythmias. It has many adverse effects, with thyroid dysfunction one of the most notable. Through various mechanisms, both thyrotoxicosis and hypothyroidism can occur secondary to amiodarone therapy. There are two types of amiodarone-induced thyrotoxicosis: type 1 occurs in those with pre-existing thyroid disease and is treated with thionamide, whereas type 2 occurs in those without and is treated with glucocorticoids. Patients with amiodarone-induced hypothyroidism may be given levothyroxine to replace thyroid hormone, but in some cases, the appropriate management may be cessation of amiodarone.

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%.

Total thyroidectomy in a patient awaiting heart transplant with amiodarone-induced thyrotoxicosis: A case report

Thyroid function may have a severe impact in cardiac function. Herein, we present the case report of a 53-year-old male patient awaiting heart transplant with amiodarone induced thyrotoxicosis that presented a marked improvement of his cardiac function after total thyroidectomy.

Early surgery: a favorable prognosticator in amiodarone-induced thyrotoxicosis-a single-center experience with 53 cases

Fewer than 100 cases of amiodarone-induced thyrotoxicosis (AIT) managed surgically have been reported worldwide. This study aims to assess the outcome of thyroidectomy under general anesthesia in a relatively large case series. A retrospective analysis of the clinical records of 53 patients who underwent thyroidectomy for AIT between 1995 and 2019 was conducted. There were 48 (90%) males and 5 females with an average age of 63.7 years. Type 1 and 2 AIT were present in 35 (66%) and 18 (34%) of patients, respectively. The mean preoperative ejection fraction (EF) was 45 ± 13%. Salvage surgery was performed in 6 (11%) patients due to decompensating heart failure and/or malignant arrhythmias. 35 (66%) patients underwent urgent surgery due to a predicted late response to medical therapy and/or the need to discontinue it. Elective surgery was performed in the remainder. A considerable improvement in mean EF occurred 12 months post-surgery (44% vs. 49%; p < 0.001). The overall survival rate following thyroidectomy was 96% at 12 months, and 83% at 5 years. No survival differences were observed based on systolic function. Cardiac-specific mortality was 11%, and these patients demonstrated a considerably shorter survival post-surgery compared to those who died of a non-cardiac cause (27 ± 18 vs. 77.5 ± 54 months; p < 0.05). Total thyroidectomy can be safely performed under general anesthesia despite severe cardiac disease. It considerably improves cardiac function and confers a survival advantage. Therefore, it should be considered early in the treatment plan of select cases.

Pathological thyroid findings in amiodarone-induced thyrotoxicosis

Amiodarone (AMD) is a class III antiarrhythmic drug whose chronic or high dosage administration alters the tests of thyroid function. AMD is also associated with hypothyroidism or thyrotoxicosis. Total thyroidectomy is an efficient treatment of AMD-induced thyrotoxicosis in cases resistant to medical therapy, worsening of cardiac function and/or severe thyrotoxicosis. Although AMD is a widely used drug, its pathological consequences are not well known. We describe the pathological findings in the thyroid gland of a patient who underwent total thyroidectomy due to AMD-induced thyrotoxicosis. The surgical specimen was macroscopically normal, but histologically showed multiple follicles totally or partially invaded by clear vacuolated (foamy) histiocytes, sometimes multinucleated. Loss of thyrocytes, breaks in the follicular basal membrane and stromal fibrosis could also be appreciated but no lymphocytic infiltrates were found. An awareness of these histopathological features is particularly important for surgical pathologists, especially as there are very few published reports describing these alterations.

Current approach to surgical management of hyperthyroidism

Hyperthyroidism is a set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to thyrotoxicosis. The most common forms of hyperthyroidism include diffuse toxic goiter (Graves' disease), toxic multinodular goiter (Plummer disease), and a solitary toxic adenoma. The most reliable screening measure of thyroid function is the thyroid-stimulating hormone (TSH) level. Options for treatment of hyperthyroidism include: antithyroid drugs, radioactive iodine therapy (the preferred treatment of hyperthyroidism among US thyroid specialists), or thyroidectomy. Massive thyroid enlargement with compressive symptoms, a suspicious nodule, Graves' orbitopathy, and patient preference are indications for surgical treatment of thyrotoxicosis. This paper reviews the current literature and controversies on the surgical approach to the management of hyperthyroidism.

Amiodarone Induced Thyrotoxicosis and Treatment Complications in a Man With Cyanotic Congenital Heart Disease: A Case Report

Background and Case: Amiodarone induced thyrotoxicosis (AIT) is a potentially life-threatening condition that exists in two main subtypes – AIT Type 1 (AIT1) and AIT Type 2 (AIT2). AIT1 is a form of iodine-induced hyperthyroidism with increased thyroid hormone synthesis, while AIT2 is a form of destructive thyroiditis with increased release of pre-formed thyroid hormone. This case report describes a patient with cyanotic congenital heart disease, who developed AIT with severe biochemical thyrotoxicosis. Due to complications to corticosteroids and thionamides, second-line treatment with cholestyramine and lithium was given which eventually restored euthyroidism, averting the need for thyroidectomy and its associated risks. Due to the presence of both typical and unusual features, the final diagnosis of AIT2 could only be retrospectively elucidated after a prolonged clinical course.

Conclusion: Corticosteroids are well-recognized to be the first-line treatment for AIT2. This case illustrates a rare phenomenon: successful treatment of AIT2 with lithium and cholestyramine. In patients who develop complications from first-line therapy, prompt treatment with alternative agents may successfully avert thyroidectomy and its associated risks.

Amiodarone-induced thyrotoxicosis

Amiodarone-induced thyrotoxicosis (AIT) are not uncommon endocrinopathies. Clinicians are sometimes faced with difficult diagnostic and therapeutic situations. The disease pathophysiology is partially understood, explaining the lack of predictive factors for occurrence. Different international recommendations for their management have been published: the most recent in 2018 by the European Thyroid Association (ETA) (Ross et al., 2016; Bartalena et al., 2018). The purpose of this paper is to present the essential concepts for their management and to review the literature since 2018.

Comparison Between Total Thyroidectomy and Medical Therapy for Amiodarone-Induced Thyrotoxicosis

CONTEXT

It is not known whether total thyroidectomy is more favorable than medical therapy for patients with amiodarone-induced thyrotoxicosis (AIT).

OBJECTIVE

To compare total thyroidectomy with medical therapy on survival and cardiac function in AIT patients.

METHODS

Observational longitudinal cohort study involving 207 AIT patients that had received total thyroidectomy (surgery group, n = 51) or medical therapy (medical therapy group, n = 156) over a 20-year period. AIT types and left ventricular ejection fraction (LVEF) classes were determined at diagnosis of AIT. Cardiac and thyroid function were reevaluated during the study period. Survival was estimated using the Kaplan-Meier method.

RESULTS

Overall mortality and cardiac-specific mortality at 10 and 5 years, respectively, were lower in the surgery group than in the medical therapy group (P = 0.04 and P = 0.01, respectively). The lower mortality rate of the surgery group was due to patients with moderate to severely compromised LVEF (P = 0.005 vs medical therapy group). In contrast, mortality of patients with normal or mildly reduced LVEF did not differ between the 2 groups (P = 0.281 and P = 0.135, respectively). Death of patients with moderate to severe LV systolic dysfunction in the medical therapy group occurred after 82 days (interquartile range, 56-99), a period longer than that necessary to restore euthyroidism in the surgery group (26 days; interquartile range, 15-95; P = 0.038). Risk factors for mortality were age (hazard ratio [HR] = 1.036) and LVEF (HR = 0.964), whereas total thyroidectomy was shown to be a protective factor (HR = 0.210). LVEF increased in both groups after restoration of euthyroidism, above all in the most compromised patients in the surgery group.

CONCLUSIONS

Total thyroidectomy could be considered the therapeutic choice for AIT patients with severe systolic dysfunction, whereas it is not superior to medical therapy in those with normal or mildly reduced LVEF.

AMIODARONE-INDUCED THYROTOXICOSIS AFTER TOTAL THYROIDECTOMY FOR METASTATIC FOLLICULAR THYROID CANCER

Objective

To describe the case of a man who developed amiodarone-induced thyrotoxicosis (AIT) after a total thyroidectomy for metastatic follicular thyroid cancer because of the effect of the drug on metastasis. To the best of our knowledge this is the first reported case of this condition.

Methods

We completed a retrospective review of medical records and laboratory results including thyroid function tests as well as imaging reports including plain radiographs, positron emission tomographs, computed tomographs, and histology reports.

Results

A 78-year-old man had undergone a total thyroidectomy for follicular thyroid cancer. He had meta-static disease in his chest and vertebrae, and after the operation he was started on suppressive levothyroxine treatment prior to ablative radioactive iodine treatment. Prior to thyroidectomy, his thyroid-stimulating hormone (TSH) concentration was 3.21 mU/L (reference range is 0.35 to 3.50 mU/L). On suppressive thyroxine replacement, his TSH concentration was 0.02 mU/L, his free thyroxine was 13 pmol/L (reference range is 8 to 12 pmol/L), and free triiodothyronine was 5.8 pmol/L (reference range is 3.8 to 6.0 pmol/L). He subsequently had a myocardial infarction and required antiarrhythmic treatment with amiodarone. Eleven days later he developed the clinical and biochemical features of thyrotoxicosis (TSH <0.01 mU/L, free thyroxine of 41 pmol/L, and free triiodothyronine of 14.7 pmol/L). His thyroxine dose was reduced and then discontinued 3 days later. AIT was the principal differential diagnosis, but before being able to determine the nature of the condition he died 18 days after his myocardial infarction.

Conclusion

AIT can still occur after total thyroidectomy if metastatic tissue is present.

Amiodarone-induced thyrotoxicosis in a pediatric patient: A rare and demanding clinical case

Thyroid dysfunction is one of the most common adverse effects of amiodarone therapy, ranging from subclinical changes to overt clinical thyrotoxicosis (AIT) and/or hypothyroidism. Due to its heterogeneity, AIT lasts as a defiant entity, leading to a thorny treatment course, particularly in pediatrics. AIT can be classified as either type 1, type 2 or mixed form based on its pathophysiology. Differentiating between the main AIT subtypes is quite relevant, since there is specific treatment for both, however, this distinction may be difficult in clinical practice. We describe a rare case of AIT in a pediatric patient, with an uncommon congenital cardiac malformation, that started amiodarone therapy due to paroxysmal supraventricular tachycardia. AIT was reported 26 months after drug onset, with a sudden and explosive emerging. This case highlights the current AIT management challenges on the highdemanding pediatric field pursuing, ultimately, an enhanced patient´s care.

Thyroid Disorders in Homozygous β-Thalassemia: Current Knowledge, Emerging Issues and Open Problems

Changes in thyroid function and thyroid function tests occur in patients with β-thalassemia major (TM). The frequency of hypothyroidism in TM patients ranges from 4% to 29 % in different reports. The wide variation has been attributed to several factors such as patients’ genotype, age, ethnic heterogeneity, treatment protocols of transfusions and chelation, and varying compliance to treatment. Hypothyroidism is the result of primary gland failure or insufficient thyroid gland stimulation by the hypothalamus or pituitary gland. The main laboratory parameters of thyroid function are the assessments of serum thyroid-stimulating hor-mone (TSH) and serum free thyroxine (FT4). It is of primary importance to interpret these measurements within the context of the laboratory-specific normative range for each test. An elevated serum TSH level with a standard range of serum FT4 level is consistent with subclinical hypothyroidism. A low serum FT4 level with a low, or inappropriately normal, serum TSH level is consistent with secondary hypothyroidism. Doctors caring for TM patients most commonly encounter subjects with subclinical primary hypothyroidism in the second decade of life. Several aspects remain to be elucidated as the frequency of thyroid cancer and the possible existence of a relationship between thyroid dysfunction, on one hand, cardiovascular diseases, components of metabolic syndrome (insulin resistance) and hypercoagulable state, on the other hand. Further studies are needed to explain these emerging issues. Following a brief description of thyroid hormone regulation, production and actions, this article is conceptually divided into two parts; the first reports the spectrum of thyroid disease occurring in patients with TM, and the second part focuses on the emerging issues and the open problems in TM patients with thyroid disorders.