Thyrotoxic Cardiomyopathy Research Articles

Reversible Thyrotoxicosis Dilated Cardiomyopathy

Thyrotoxic cardiomyopathy is a rarely diagnosed disease in patients coming into the hospital with hyperthyroidism for the first time. The objective of this case study is to present the rare case of a patient, who was diagnosed with a thyrotoxic cardiomyopathy for the first time. A 47-year old Saudi male was presented in the King Abdulaziz Medical City in Jeddah, Saudi Arabia in March 2017, with a two-week history of progressive dyspnea, orthopnea, paroxysmal nocturnal dyspnoea, and atrial fibrillation. Following physical examinations and investigations, the diagnosis of thyrotoxicosis was performed. Initially, he was treated with Methimazole, followed by radioactive therapy, which resulted in the patient’s full recovery from cardiomyopathy through the treatment of his thyrotoxicosis. One of the first symptoms, the manifestation of thyrotoxicosis, is thyrotoxic dilated cardiomyopathy. In most cases, it may be completely reversible through the appropriate treatment of the thyrotoxicosis.

A Pregnant Lady with Thyrotoxic Cardiomyopathy and Pulmonary Hypertension

Thyrotoxic cardiomyopathy is potentially life threatening complications of thyrotoxicosis during pregnancy due to its harmful effects both on mother and fetus. We present a case of 32-year-old pregnant lady presented with non-productive cough, palpitation, restlessness, sweating and weakness after minimum exertion with a small swelling on the right side of her neck for three months. There was tachycardia with normal blood pressure, first and second heart sound were soft with pansystolic murmur on mitral and tricuspid area. After all laboratory investigations, she was diagnosed as dilated cardiomyopathy with moderate to severe pulmonary hypertension with toxic multi nodular goiter with 13 weeks of pregnancy.The thyrotoxic cardiomyopathy during pregnancy is rare due to difficulties in diagnosis. However, physicians should be aware of the risk posed by thyrotoxic cardiomyopathy during pregnancy.
 KYAMC Journal Vol. 11, No.-1, April 2020, Page 54-56

Нарушение микроэлементной обеспеченности: вклад в формирование тиреотоксической кардиомиопатии у пациентов с болезнью Грейвса

Нарушение микроэлементной обеспеченности: вклад в формирование тиреотоксической кардиомиопатии у пациентов с болезнью Грейвса

Reversible thyrotoxic cardiomyopathy: a case report

<p>Hyperthyroidism significantly affects the hemodynamics of the cardiovascular system. It is associated with development of atrial fibrillation, high output cardiac failure, pulmonary hypertension and dilated cardiomyopathy (DCM). In this paper we report a case of thyrotoxicosis induced cardiomyopathy. She was a 54 year old woman who presented with cardiomegaly (dilatation of all four chambers of the heart) secondary to Graves’ disease. She was treated with anti-thyroid drugs, β Blockers and diuretic and her euthyroid status was restored in 6 weeks. A repeat echocardiogram done at this point of time showed normal cardiac function with normalization of ejection fraction. So this was a case of reversible thyrotoxic cardiomyopathy.</p>

Prognostic value of the determination of interleukin-8 in development of thyrotoxic cardiomyopathy in patients with Graves' disease

Prognostic value of the determination of interleukin-8 in development of thyrotoxic cardiomyopathy in patients with Graves' disease

Thyrotoxic Periodic Paralysis and Cardiomyopathy in a Patient with Graves’ Disease

Thyrotoxic periodic paralysis (TPP) and cardiomyopathy are two established complications of thyrotoxicosis. Emergent management is essential as TPP and cardiac events secondary to thyrotoxic cardiomyopathy can be fatal. We report a unique case of a patient with Graves’ disease presenting with symptoms secondary to both these complications. A 34-year-old Hispanic male, diagnosed with Graves’ disease, non-compliant with his medications, presented to the emergency room (ER) with complaints of generalized weakness, palpitations, chest pain and multiple episodes of nausea and vomiting for one day. On presentation, the patient was tachycardiac, had a systolic flow murmur and decreased motor strength in all extremities. Blood work showed a potassium of 1.8 millimoles per liter, cardiac troponin of 0.04 nanograms per milliliter and a thyroid panel consistent with hyperthyroidism. Electrocardiogram showed atrial flutter. In the ER, Propranolol, Propylthiouracil and Hydrocortisone were administered to prevent thyroid storm. Potassium was repleted, and the patient developed rebound hyperkalemia. He was given calcium gluconate, insulin, sodium polystyrene and admitted to the medical intensive care unit (MICU) for further management. Echocardiogram revealed severely decreased left ventricular systolic function and an ejection fraction of 26-30%. He was diagnosed with cardiomyopathy secondary to thyrotoxicosis. He was stabilized with Methimazole, Propranolol, Lisinopril and discharged on day nine with these medications and an outpatient follow-up appointment. Thyrotoxicosis can be life-threatening. This case shows a unique instance where a Hispanic patient presented with two complications of this phenomena. The pathogenesis of TPP involves increased responsiveness of the beta-adrenergic receptors, which leads to increased activity of the Sodium/Potassium (Na+/K+) ATPase pump and a transcellular shift of potassium into cells. The condition can resolve acutely with the administration of potassium. It is important to monitor the rate of potassium replacement as rebound hyperkalemia can occur, as this case demonstrates. Propranolol is an integral part of treatment as it is a beta-adrenergic receptor blocker and blocks the peripheral conversion of thyroxine (T4) to triiodothyronine (T3) in high doses. Thyrotoxic cardiomyopathy is one of the many cardiac complications that can be precipitated by Graves’ disease. One probable cause is the chronic tachycardia that patients with hyperthyroidism develop. Treatment entails managing the hyperthyroidism by starting the patient on beta blockers and anti-thyroid drugs or radioactive iodine uptake. Diuretics can be started to manage patients with heart failure. It is important to identify and treat the condition immediately to prevent grave complications.

A Case Report of Dilated Biventricular Heart Failure from Hyperthyroidism: A Rare Presentation

Hyperthyroidism is a common metabolic disorder with many cardiovascular manifestations. In rare cases, untreated hyperthyroidism can lead to thyrotoxic cardiomyopathy with severe left ventricular (LV) dysfunction. This case report aims to discuss the pathogenesis of heart failure in hyperthyroidism and the available treatment options.A 51-year-old male with a past history of untreated hyperthyroidism presented to our hospital for the evaluation of shortness of breath and dysphagia. Workup revealed atrial flutter and severe biventricular dilated cardiomyopathy. Stabilization thyroidectomy was performed due to dysphagia, and treatment with oral antithyroid medications was initiated. The patient was discharged on synthroid and beta-blockers.Untreated hyperthyroidism can lead to biventricular failure even in the young. Untreated hyperthyroidism leads to significant mortality and morbidity. Untreated hyperthyroidism is associated with atrial fibrillation, heart failure, pulmonary hypertension (PH), and angina-like symptoms. Further studies should be done to evaluate the pathogenesis of Graves/Goiter hyperthyroidism and the least-invasive, safe, and definitive treatment options should be discovered. Current treatment options are limited and include medication that needs to be taken lifelong; they are associated with toxicity. Radioactive iodine ablation comes with the drawback of long-term replacement therapy. The last option is surgery, which is invasive and has its own complications.

Genetic and Molecular Aspects of Thyrotoxic Cardiomyopathy

Genetic and Molecular Aspects of Thyrotoxic Cardiomyopathy

Clinicopathological features and comorbidities of cats with mild, moderate or severe hyperthyroidism: a radioiodine referral population.

This study sought to explore the clinicopathological features and comorbidities of cats with mild, moderate and severe hyperthyroidism in a radioiodine referral population. Medical records were reviewed, along with results of serum biochemistry, urinalysis, systolic blood pressure and diagnostic imaging performed at the time of radioiodine referral. Cats were grouped by total thyroxine (TT4) levels as mildly (TT4 60.1-124.9 nmol/l), moderately (TT4 125-250 nmol/l) or severely (TT4 >250 nmol/l) hyperthyroid at the time of diagnosis and referral. Thirty percent (42/140) of the cats were <10 years old at diagnosis. In 24.3% (34/140), hyperthyroidism was diagnosed incidentally. The time between diagnosis and referral for radioiodine was significantly longer in cats with severe hyperthyroidism at the time of referral ( P = 0.004). An increase in severity group between the time of diagnosis and referral occurred in 38.6% (54/140) of cats. At referral, 54.3% (25/46) of cats with mild, 66.7% (42/63) with moderate and 80.6% (25/31) with severe hyperthyroidism were unstable despite ongoing medical or dietary management. The prevalence of cardiac abnormalities was significantly increased in cats with severe hyperthyroidism ( P = 0.014) compared with those with mild or moderate hyperthyroidism. There was no significant difference in the likelihood of renal disease ( P = 0.708) or hypertension ( P = 0.328) between the groups. Incidental diagnosis of hyperthyroidism occurs commonly, potentially owing to increased disease screening. Cats with severe hyperthyroidism at referral were more likely to be chronically hyperthyroid with a history of poor stabilisation. This subset of patients was significantly more likely to have cardiac abnormalities. Thyrotoxic cardiomyopathy may ultimately affect patient suitability for curative treatments (radioiodine or thyroidectomy) owing to higher anaesthetic risks and potential for decompensation into congestive heart failure with the stress of travel and hospitalisation. Curative therapy should be considered before the development of severe hyperthyroidism.

Evaluation of cardiovascular complexities and quality of life related to health in Chinese patients with thyrotoxic heart disease secondary to toxic diffuse goiter

The common reason behind the development of thyrotoxic heart disease is toxic diffuse goiter via hyperthyroidism. The effect of cardiovascular complexities and quality of life related to health in Chinese patients with thyrotoxic heart disease secondary to toxic diffuse goiter has been evaluated. During July 2013-June 2015 patients were diagnosed with thyrotoxic heart disease secondary to toxic diffuse goiter. Clinical assessment was performed at baseline and after restoration of euthyroid state follow-up. A questionnaire was created and used to study the quality of life related to health in them. Cohort study data for 73 patients was obtained. However, around half (35) of these patients with thyrotoxic heart disease secondary to toxic diffuse goiter were agreed to participate further in investigation of their quality of life related to health. The frequency of cardiovascular complexities before and after anti-thyroid therapy was recorded. A significant reduction in respective values was observed as: thyrotoxic cardiomyopathy (78% vs. 24%), ventricular extrasystole (72% vs. 7%), systolic blood pressure (158 vs. 126; in mm), diastolic blood pressure (85 vs. 68; in mm), congestive cardiac failure (68 vs. 18; in %), resting heart rate (124 vs. 76; in bpm) and atrial fibrillation (71 vs. 19; in %). In all the domains, improvement in quality of life related to health was observed. There is a strong association of reduction in cardiovascular complexities and of increment in quality of life related to health with respect to restoration of euthyroidism in Chinese patients.

Successful treatment of severe thyrotoxicosis with radioiodine therapy in a patient with thyrotoxic cardiomyopathy

Thyrotoxic cardiomyopathy (TCM) is a potential life threatening complication of thyrotoxicosis which is potentially reversible with early achievement of euthyroid state. Management of severe thyrotoxicosis in the presence of TCM is a challenging task, especially when thioamides are contraindicated. A 58 yr old male with poorly controlled Grave’s disease of 10 years presented with worsening symptoms of thyrotoxicosis and leg swelling. On examination he was thyrotoxic with a smooth diffuse goiter and also had inactive Grave’s orbitopathy. He had irregularly irregular pulse rate, grossly elevated jugular venous pulses, enlarged heart with tricuspid regurgitation and pulmonary hypertension. FT4 was >8.34 ng/dl (0.8-1.6 ng/dl), free T3 was 20.39 pg/ml (2.3-4.3 pg/ml) and TSH was 0.01 mU (0.5-5.0 mU/L). Serial ECGs showed slow atrial fibrillation with transient complete hear block and echocardiogram showed dilated TCM. He had pancytopenia, most likely resulting from concurrent carbimazole therapy. Medical management of cardiomyopathy was initiated along with lithium, prednisolone and judicious use of beta blockers to control his thyroid status. Within one week he was subjected to radioactive iodine (RAI) therapy following which he was rendered euthyroid . RAI is a safe mode of definitive therapy in patients with TCM provided carful stabilization of underlying cardiac status. Early definitive therapy is required to achieve euthyroid status to minimize irreversible TCM.

Relationship between the abnormal diastolic vortex structure and impaired left ventricle filling in patients with hyperthyroidism.

Intraventricular hydrodynamics plays an important role in evaluating cardiac function. Relationship between diastolic vortex and left ventricular (LV) filling is still rarely elucidated. The aim of this study was to evaluate the evolution of vortex during diastole in hyperthyroidism (HT) and explore the alteration of hydromechanics characteristics with sensitive indexes.Forty-three patients diagnosed with HT were classified into 2 groups according to whether myocardial damage existed: simple hyperthyroid group (HT1, n = 21) and thyrotoxic cardiomyopathy (HT2, n = 22). Twenty-seven age- and gender-matched healthy volunteers were enrolled as the control group. Offline vector flow mapping (VFM model) was used to analyze the LV diastolic blood flow patterns and fluid dynamics. Hemodynamic parameters, vortex area (A), circulation (C), and intraventricular pressure gradient (ΔP), in different diastolic phases (early, mid, and late) were calculated and analyzed.HT2, with a lower E/A ratio and left ventricular ejection fraction (LVEF), had a larger left atrium diameter (LAD) compared with those of the control group and HT1 (P < .05). Compared with the control group, the vortex size and strength, intraventricular pressure gradient during early and mid-diastole were higher in HT1 and lower in HT2 (P < .05). And in late diastole, the vortex size and strength, intraventricular pressure gradient of HT2 became higher than those of the control group (P < .05). Good correlation could be found between CE and E/A (P < .05), CM and ΔPM (P < .01), CL and FT3 (P < .05).VFM is proven practical for detecting the relationship between the changes of left ventricular diastolic vortex and the abnormal left ventricular filling.

Relationship between the Abnormal Diastolic Vortex Structure and Impaired Left Ventricle Filling in Patients with Hyperthyroidism

Intraventricular hydrodynamics plays an important role in evaluating cardiac function. Relationship between diastolic vortex structures and left ventricular (LV) filling is still rarely reported. This study aimed to evaluate the evolution of intraventricular fluid dynamics during diastole in hyperthyroidism (HT), and to explore the alteration of hydromechanics characteristics with sensitive indices. Forty-three patients diagnosed with HT were divided into two groups according to whether myocardial damage existed: simple hyperthyroid group (HT1, n = 21) and thyrotoxic cardiomyopathy (HT2, n = 22). Twenty-seven age- and gender-matched healthy volunteers were enrolled as the control group. Offline vector flow mapping (VFM model) was used to analysis the LV diastolic blood flow patterns and fluid dynamics. Hemodynamic parameters like area (A), circulation (C) and intraventricular pressure gradient (△P) in different diastolic phase (early, mid, and late) were calculated and analyzed. HT2, with a lower E/A ratio and left ventricular ejection fraction (LVEF), had larger left ventricular end-diastolic diameter (LVEDD) and left atrium diameter (LAD) compared with the control group and HT1(P <0.05). Vortex displayed a typical biphasic temporal course during diastole in these three groups. In early diastole, vortices of the controls were smaller and weaker than those of HT1, larger and stronger than those of HT2 (P < 0.05 for both). Vortices of these three groups increased in mid-diastole at the same pace and differences remained (P < 0.05 for both). Then vortices in HT2 developed so fast that exceeded the control group, but still below HT1 during the end of diastole. The intraventricular pressure gradient during early and mid-diastole (△PE, △PM) were higher in HT1 and lower in HT2 compared with those of the control group (P <0.05). However, the intraventricular pressure gradient (△PL) of HT2 increased and was higher than that of the control group in late diastole (P < 0.05). Good correlation could be found between CE and E/A (P < 0.05), CM and △PM (P < 0.01), CL and FT3 (P < 0.05). VFM can reflect the abnormal left ventricular filling by showing the changes of left ventricular diastolic vortex.

HYPERTHYROIDISM AND ATRIAL FIBRILLATION

Review on a problem of the development of atrial fibrillation in patients with thyrotoxicosis is presented. Thyrotoxicosis is one of the most frequent endocrine diseases, conceding only to a diabetes mellitus. The most frequent reasons of hyperthyroidism are Graves’ disease and functional thyroid autonomy. The authors give an analysis of data on the cardiac effects of thyrotoxicosis, features of heart remodeling under the influence of thyroid hyperfunction, prevalence of atrial fibrillation in thyrotoxicosis, depending on age, as well as the possibility of restoring sinus rhythm in the combination of these diseases. Particular attention is paid to the effect on the heart of subclinical thyrotoxicosis, which is defined as a dysfunction of the thyroid gland, characterized by low serum concentration of thyrotropin, normal values of free thyroxine and free triiodothyronine. Subclinical hyperthyroidism is also capable of causing heart remodeling and diastolic dysfunction. Prevalence of thyrotoxicosis in elderly people is higher in areas of iodine deficiency; it is relevant for our country due to the large territory of iodine deficiency. In elderly patients, the cardiac effects of thyrotoxicosis prevail in the clinical picture, that makes it difficult to diagnose endocrine disorders, and correction of thyrotoxicosis is critically important for the successful control of the heart rhythm. The article also discusses the problem of thyrotoxic cardiomyopathy, caused by the toxic effect of excess thyroid hormones: features of this heart disorder, factors affecting its formation, clinical significance and contribution to the development of rhythm disturbances. The greatest significance is the development of atrial fibrillation as a result of thyrotox-icosis in older patients who already have various cardiovascular diseases. Atrial fibrillation is the most frequent heart rhythm disorder in thyrotoxicosis. The main cause of arrhythmia in hyperthyroidism is the simultaneous existence of frequent focal impulses and circular motions of the excitation wave – the mechanism re-entry. Successful treatment of atrial fibrillation in patients with thyrotoxicosis is possible only when euthyroidism is achieved. In most cases, after the elimination of thyrotoxicosis, a spontaneous restoration of the sinus rhythm is observed. The chances of sinus rhythm restoration are lower in elderly patients with concomitant organic diseases of the myocardium or long-term atrial fibrillation. Moreover, even radically cured thyrotoxicosis leads to deterioration in the life prognosis.

Thyrotoxic Cardiomyopathy and Heart Failure in Patients with Toxic Goiter. Changes after Surgery

Changes in the severity of heart failure in patients with toxic goiter after surgery are insufficiently studied.The objective of the research was to study changes in cardiac disorders in the remote period after surgical treatment of toxic goiter.Material and methods. The study included 48 patients with toxic goiter and moderate thyrotoxicosis and 102 patients with severe thyrotoxicosis. Cardiac disorders and changes in cardiac function after surgery were studied using the following gradation: good, satisfactory, unsatisfactory results and ineffective treatment.Results. Good and satisfactory results of surgical treatment in patients with moderate thyrotoxicosis were obtained in 47 (98%) cases and in patients with severe thyrotoxicosis they were achieved in 45 (44%) cases. Unsatisfactory outcome was determined by the severity of thyrotoxicosis, its duration, and low exercise tolerance during the 6-min walking test.Conclusions. Persistent severe thyrotoxicosis leads to atrial fibrillation and heart failure, which in most cases (66%) after surgical treatment of toxic goiter do not undergo reversible changes.

SNP Ser38Gly in the β-subunit of potassium channel gene KCNE1 and thyrotoxic cardiomyopathy in patients with Graves’ disease

The relevance of the research. The risk factors of developing severe thyrotoxic cardiomyopathy (TCMP) are not certainly determined now. But it is essential to choose the optimal approach to care. Recent studies show that even patients of the same sex, with similar age, duration of thyrotoxicosis and hormones’ level differ in a severity of cardiomyopathy. So, scientists began to search for genetic risk predictors of the heart damage, caused by thyrotoxicosis. Among possible genetic predictors of thyrotoxicosis are single nucleotide polymorphisms in genes, that expression is regulated by thyroid hormones or genes, that are involved in developing of non-thyrotoxic cardiac pathology. Aim. To investigate the possible association of the polymorphism Ser38Gly in KCNE1 gene with different manifestations of thyrotoxic cardiomyopathy, especially with atrial fibrillation and cardiac remodeling. Materials and methods. 155 patients with thyrotoxicosis caused by Graves’ disease were enrolled. Genotyping was also made in 187 healthy blood donors – the control group. Genotyping was performed by real time polymerase chain reaction. Results. Our results show an interaction of the single nucleotide polymorphism Ser38Gly in KCNE1 gene with TCMP only in patients aged 45 and older. In this age group atrial fibrillation was significantly more prevalent in GG genotype carriers: 35.3% (GG) vs 13.9% (AG+AA) ( p = 0.037). Also, there was a significant difference in systolic blood pressure (SBP) by KCNE1 codon 38 genotypes. SBP were significantly higher in allele G gomozygotes as compared to allele A carriers: 124.89 ± 15.14 mm Hg vs 131.35 ± 15.32 mm Hg ( p = 0.012). Conclusion. The fact, that association of the polymorphism Ser38Gly with atrial fibrillation was shown only in group with patients older than 45 years, proves that its influence is of a lower value in comparison with “traditional” risk factors. There was no significant difference among genotypes in severity of TCMP and types of myocardial re-modeling.

State of the art paper Hyperthyroidism and cardiovascular complications: a narrative review on the basis of pathophysiology

Cardiovascular complications are important in hyperthyroidism because of their high frequency in clinical presentation and increased mortality and morbidity risk. The cause of hyperthyroidism, factors related to the patient, and the genetic basis for complications are associated with risk and the basic underlying mechanisms are important for treatment and management of the disease. Besides cellular effects, hyperthyroidism also causes hemodynamic changes, such as increased preload and contractility and decreased systemic vascular resistance causes increased cardiac output. Besides tachyarrythmias, impaired systolic ventricular dysfunction and diastolic dysfunction may cause thyrotoxic cardiomyopathy in a small percentage of the patients, as another high mortality complication. Although the medical literature has some conflicting data about benefits of treatment of subclinical hyperthyroidism, even high-normal thyroid function may cause cardiovascular problems and it should be treated. This review summarizes the cardiovascular consequences of hyperthyroidism with underlying mechanisms.

Irbesartan prevents myocardial remodeling in experimental thyrotoxic cardiomyopathy

This study evaluated the effects of irbesartan and propranolol on thyroid hormone (TH)-induced cardiac functional and structural remodeling. A rat model of thyrotoxicosis was established by daily intraperitoneal injections of L-thyroxine (T(4), 100 μg/kg) for 4 weeks. Forty Sprague-Dawley rats were randomly divided into four groups (n = 10 each): control group, T(4) group (T(4) alone), T(4) plus irbesartan group (T(4)-Irb, 30 mg/kg), and T(4) plus propranolol group (T(4)-Pro, 0.5mg/mL of drinking water). Cardiac chamber size and functional parameters were measured by echocardiography and cardiomyocyte diameter. Heart rate (HR) and cardiac fibrosis were determined. T(4) alone showed significantly increased HR and cardiomyocyte width (25.0 ± 1.77 vs. 18.8 ± 0.84 μm, P < 0.001) with fibrosis, reduced left ventricle (LV) longitudinal strain (S(long); -16.0 ± 6.27 vs. -22.7 ± 5.19 %, P < 0.001) compared with control. When compared with T(4) alone, T(4)-Irb showed significantly improved LV S(long) (-21.4 ± 1.84 vs. -16.0 ± 6.27 %, P =0.017) and reduced cardiomyocyte width (21.0 ± 1.0 vs. 25.0 ± 1.77 μm, P =0.002) with comparable HR (458.4 ± 24.3 vs. 486.6 ± 30.1 bpm, P = 0.086). However, T(4)-Pro showed significantly reduced HR with improved LV S(long) without alteration of cardiomyocyte width and fibrosis compared with T(4) alone. In conclusion, renin-angiotensin system (RAS) blocking by irbesartan could significantly attenuate TH-induced cardiac structural and functional remodeling. However, HR reduction by propranolol could not alternate structural remodeling, which may implicate the RAS as having an important role in thyrotoxic cardiomyopathy beyond tachycardia.

Hyperthyroid-Induced Cardiomyopathy In An Adult: A Case Report

Although there is ample evidence of hyperthyroidism associated with heart failure at old age, few reports exist in the medical literature regarding adults who experience thyrotoxic cardiomyopathy. In this report we describe an adult patient who presented for urgent care with vague symptoms of palpitations, headaches, lower-extremity swelling, and dyspnea on exertion and was found to have congestive heart failure (CHF) secondary to hyperthyroidism.

Thyroid Storm and Reversible Thyrotoxic Cardiomyopathy After Ingestion of Seafood Stew Thought to Contain Marine Neurotoxin

Thyroid storm and severe decompensated thyrotoxicosis are life-threatening diseases, requiring immediate treatment in an intensive care unit. Thyrotoxic heart disease is common in patients with hyperthyroidism; thyrotoxic cardiomyopathy with poor left ventricular systolic function is rare. Here, we report a patient who presented with severe decompensated thyrotoxicosis and reversible thyrotoxic cardiomyopathy after ingestion of a mixed seafood stew thought to contain tetrodotoxin or a related marine neurotoxin. The patient was a 50-year-old woman who was seen at the emergency room of another hospital with altered mentality and flaccid quadriplegia after eating a mixed seafood stew. At the other hospital, she was diagnosed as having tetrodotoxin intoxication on the basis of her clinical presentation. The patient was placed on assisted ventilation and transferred to our hospital the following day because of persisting fever, tachycardia, and respiratory depression. Upon admission, thyroid storm was diagnosed on the basis of thyroid function tests (total triiodothyronine was 354 ng/dL, free thyroxine was 3.45 ng/dL, and thyroid-stimulating hormone was <0.01 mU/L) and clinical manifestations. On the third hospital day, she complained of chest discomfort and progressively worsening dyspnea. Echocardiography showed reduced left ventricular systolic function (left ventricular ejection fraction, 47%; left ventricular fractional shortening, 24.4%) with regional wall motion abnormality of anteroseptal wall and apex and diastolic dysfunction (grade 1, relaxation abnormality), suggesting thyrotoxic cardiomyopathy. She was treated with 10 mCi of radioactive iodine and methimazole, and her thyroid and cardiac function normalized. The patient reported here developed thyroid storm and cardiac decompensation shortly after a clinical event consistent with ingestion of marine neurotoxin. This adds to the list of stresses that have been associated with thyroid storm and emphasizes the need to fully evaluate patients who, on initial evaluation, appear to have only a single disorder.