Thyroid Storm and Ventricular Tachycardia

Data Analysis and Systematic Scoping Review on the Pathogenesis and Modalities of Treatment of Thyroid Storm Complicated with Myocardial Involvement and Shock

Thyroid storm (TS) is a rare and fatal endocrine emergency that occurs due to undiagnosed and inadequately treated hyperthyroidism after stressful conditions in patients with thyroid disorders. The objective of this systematic scoping review was to better understand the pathophysiology of TS and its complications, in terms of myocardial affection, tachyarrhythmia, and cardiogenic shock. In addition, we explored the pharmacological, mechanical, and surgical treatments for TS. We also evaluated the outcomes of TS according to sex and cardiac involvement. Additionally, analytical analysis was performed on the selected data. A literature review of peer-reviewed journals was carried out thoroughly using medical terms, MeSH on PubMed, Google Scholar, and combinations such as thyrotoxicosis-induced cardiomyopathy, thyroid storm, cardiogenic shock, myocardial infarction, endocrine emergency, Burch-Wartofsky score, extracorporeal circulatory support, and thyroidectomy. A total of 231 papers were eligible (2 retrospective studies, 5 case series, and 224 case reports) with a total of 256 TS patients with cardiac involvement between April 2003 and August 2023. All age groups, sexes, patients with TS-induced cardiomyopathy, non-atherosclerotic myocardial infarction, tachyarrhythmia, heart failure, shock, and different forms of treatment were discussed. Non-English language articles, cases without cardiac involvement, and cases in which treatment modalities were not specified were excluded. Female sex was predominant, with 154 female and 102 male patients. Approximately 82% of patients received beta-blockers (BBs), 16.3% were placed on extracorporeal membrane oxygenation (ECMO) support, 16.3% received therapeutic plasma exchange (TPE), and 13.8% underwent continuous renal replacement therapy (CRRT), continuous venovenous hemofiltration (CVVHD), or dialysis. Overall, 18 females and 16 males died. BB-induced circulatory collapse, acute renal failure, CRRT, and ventricular fibrillation were significantly associated with mortality. Awareness of TS and not only thyrotoxicosis is vital for timely and appropriate treatment. The early diagnosis and management of TS in cardiac settings, including pharmacological, mechanical, and surgical modalities, can save high-risk patients. Sex matters in the presentation, treatment, and mortality of this population. However, further large-scale, and well-designed studies are required.

Cardiac arrest in myocardial infarction with non-obstructive coronary artery (MINOCA) secondary to thyroid dysfunction

A man in his 40s who was previously well had an out-of-hospital cardiac arrest. Postresuscitation ECG showed ST-elevation myocardial infarction (MI). Emergency coronary angiogram revealed MI with non-obstructive coronary arteries (MINOCA) with evidence of spasm in the right coronary artery. Both his echocardiogram and cardiac MRI revealed a normal heart. Further workup showed markedly elevated free T4 (99.5 pmol/L) and free T3 (26.7 pmol/L) with low thyroid stimulating hormone (<0.02 pmol/L) in keeping with thyroid storm. He also had an elevated adjusted calcium level (2.84 mmol/L), which could have contributed to his coronary artery spasm. His peak troponin T was elevated at 798 ng/L (<14) suggesting myocardial damage. He was treated with propylthiouracil, steroids, beta-blocker, calcium channel blocker and intravenous fluids. The patient achieved a full recovery and was discharged home. This is an unusual case of thyroid dysfunction resulting in coronary artery spasm, cardiac arrest and MINOCA.

Thyroid Hormone Plays an Important Role in Cardiac Function: From Bench to Bedside

Thyroid hormones (THs) are synthesized in the thyroid gland, and they circulate in the blood to regulate cells, tissues, and organs in the body. In particular, they exert several effects on the cardiovascular system. It is well known that THs raise the heart rate and cardiac contractility, improve the systolic and diastolic function of the heart, and decrease systemic vascular resistance. In the past 30 years, some researchers have studied the molecular pathways that mediate the role of TH in the cardiovascular system, to better understand its mechanisms of action. Two types of mechanisms, which are genomic and non-genomic pathways, underlie the effects of THs on cardiomyocytes. In this review, we summarize the current knowledge of the action of THs in the cardiac function, the clinical manifestation and parameters of their hemodynamics, and treatment principles for patients with hyperthyroid- or hypothyroid-associated heart disease. We also describe the cardiovascular drugs that induce thyroid dysfunction and explain the mechanism underlying the thyroid toxicity of amiodarone, which is considered the most effective antiarrhythmic agent. Finally, we discuss the recent reports on the involvement of thyroid hormones in the regulation of myocardial regeneration and metabolism in the adult heart.

<p>Malignant Arrhythmias as the Unmasked Manifestation of Thyroid Storm</p>

Thyroid storm is usually due to a severe exacerbation of a preexisting thyrotoxicosis, which later leads to decompensation in different organ systems. Thyroid storm with malignant arrhythmia is rare, but the mortality rate is high. Malignant arrhythmia has usually occurred in some patients with hypokalemia or ischemic heart disease. The presentation of these arrhythmias in the initial phase of the disease is much less common, and only a few isolated cases are described in the scientific literature. This paper analyzes and summarizes the clinical characteristics of this disease through literature reviews, for clinicians early detection and diagnosis of this disease. We report a 51-year-old woman with diarrhoea, fever, thyroid storm, ventricular fibrillation and no potential heart disease. The case report is discussed using relevant data from literature. A total of 9 patients were reported in the literature, totalling 10 cases with ours, including 7 cases of ventricular fibrillation and 3 cases of ventricular tachycardia. Most of the treatments were antithyroid drugs, hormones and beta-receptor blockers, and 3 death cases. Patients with thyroid crisis need to be closely monitored for malignant arrhythmias. Early diagnosis and treatment may save lives.

A rare case of hypokalemic ventricular tachycardia in a patient with thyrotoxic periodic paralysis

Thyrotoxic periodic paralysis (TPP) is a potentially fatal complication of hyperthyroidism, characterized by recurrent muscle paralysis and hypokalemia. We present a case of a 32-year-old apparently healthy male patient, who presented with acute paraparesis associated with hypokalemia (K: 1.6 mmol/L), complicated by ventricular tachycardia (VT). Advanced cardiac life support was initiated with an amiodarone infusion, and eventually QRS complex narrowed and wide complex tachycardia resolved. Intravenous potassium chloride (KCl) 40 mEq over 2-3 h and oral KCL 40 mEq were administered to treat the electrolyte imbalance. Patient paralysis was quickly reversed; motor function was regained with movement of the lower extremities. This case highlights the importance of early recognition and prompt treatment of TPP as a differential diagnosis for muscle weakness, especially in the setting of severe hypokalemia. It is important to pay attention to the possibility of the development of lethal VT associated with hypokalemia in the setting of hyperthyroidism and thyrotoxic paralysis.

COMPARISON OF CARDIAC ARRHYTHMIA TYPES BETWEEN HYPERTHYROID PATIENTS WITH GRAVES' DISEASE AND TOXIC NODULAR GOITER

Purpose

Previous studies have demonstrated the relationship between hyperthyroidism and increased risk of cardiac arrhythmias. The most common causes of hyperthyroidism are Graves' disease (GD) and toxic nodular goiter (TNG). The aim of our study was to demonstrate if the underlying mechanism of hyperthyroidism, in other words autoimmunity, has an impact on the type of cardiac arrhythmias accompanying hyperthyroidism.

Method

Twenty patients with TNG and 16 patients with GD who had overt hyperthyroidism were included in the study. Age, sex, thyroid hormone levels, thyroid autoantibody positivity, thyroid ultrasonography and scintigraphy results were recorded. 24-hour Holter ECG monitoring was performed in all patients.

Results

Mean age was significantly higher in the TNG group compared to the GD group (62.9±11.5 vs. 48.9±8.6 years, p=0.001). Free T3 was significantly higher (7.87±3.90 vs. 5.21±1.53 pg/mL, p=0.033) in the GD group while free T4 and TSH levels were similar between the two groups. In 24-hour Holter ECG recordings nonsustained ventricular tachycardia (VT) rates were significantly higher in the GD group than in TNG group [18.75% (n=3/16) vs. 0% (n=0/20), respectively, (p=0.043)]. Paroxysmal atrial fibrillation (AF) rates were significantly higher in the TNG group compared to GD group [(30% (n=6/20) vs. 0% (n=0/16), respectively, (p=0.016)].

Conclusion

Although free T3 levels were lower, paroxysmal AF rates were found significantly higher in the TNG group which may be associated with significantly higher age of this group. On the other hand, higher rate of nonsustained VT in the GD group may be related to either significantly higher free T3 levels or autoimmunity.

Sudden cardiac arrest as a presentation of Brugada syndrome unmasked by thyroid storm

An 18-year-old man suffered a sudden cardiac arrest with ventricular fibrillation and was successfully resuscitated. He had neither a medical nor family history of cardiac disease/sudden death, but was known to have Graves' disease, for which he was treated with radioactive iodine. Recently, block-and-replacement therapy had been discontinued to evaluate thyroid functioning. On admission, thyroid hormone levels were markedly elevated, suggesting thyroid storm due to residual Graves' disease. The patient was treated with propylthiouracil, hydrocortisone and Lugol solution. ECG showed repolarisation patterns suggestive of an underlying type 1 Brugada syndrome (BS). These findings were confirmed by an additional ajmaline test. An implantable cardioverter defibrillator was implanted to prevent future arrhythmias. The patient underwent total thyroidectomy 9 months later and recovered completely. To the best of our knowledge, this is the first reported case of a sudden cardiac arrest as a presentation of BS unmasked by thyroid storm.

Unusual Manifestation of Graves' Disease: Ventricular Fibrillation

BACKGROUND

It is well known that thyrotoxicosis causes rhythm disorders including sinus tachycardia, atrial fibrillation, and atrial flutter. Atrial fibrillation is the most common arrhythmia in thyrotoxicosis, occurring in 5-15% of patients over 60 years of age, whereas ventricular arrhythmia is an unusual manifestation.

CASE REPORT

An 18-year-old Japanese woman was admitted to our emergency department because of loss of consciousness caused by ventricular fibrillation. She had been diagnosed with Graves' disease only 5 days earlier and had no other past medical history. Blood examination showed no obvious abnormality except thyrotoxicosis, and coronary angiography revealed patent coronary arteries. She was diagnosed with thyroid storm due to Graves' disease and is currently healthy during outpatient follow-up.

CONCLUSION

This case highlights that thyrotoxicosis can, albeit extremely rarely, cause ventricular fibrillation even in the absence of hypokalemia or underlying cardiovascular disease.

A case of thyroid storm with cardiac arrest

A 23-year-old man became unconscious while jogging. He immediately received basic life support from a bystander and was transported to our hospital. On arrival, his spontaneous circulation had returned from a state of ventricular fibrillation and pulseless electrical activity. Following admission, hyperthyroidism led to a suspicion of thyroid storm, which was then diagnosed as a possible cause of the cardiac arrest. Although hyperthyroidism-induced cardiac arrest including ventricular fibrillation is rare, it should be considered when diagnosing the cause of treatable cardiac arrest.

Amiodarone-induced destructive thyroiditis associated with coronary artery vasospasm and recurrent ventricular fibrillation

A 55-year-old male on long-term amiodarone therapy presented with ischaemic chest pain and recurrent unwitnessed syncope. Interrogation of his internal cardiac defibrillator, which had been inserted 4 years earlier, revealed two episodes of ventricular fibrillation, the timing of which corresponded to his syncopal events. Severe spontaneous coronary artery vasospasm was observed on coronary angiogram. Thyroid function testing revealed severe hyperthyroidism with a diagnosis of type 2 amiodarone-induced thyrotoxicosis (AIT) subsequently made. Treatment with prednisolone therapy was commenced and thyroid function rapidly normalized. Prednisolone was weaned without recurrence of hyperthyroidism and on last review, 6 months after initial presentation, he remains free from further chest pain and arrhythmias. Our patient's presentation is a very rare case of AIT-associated coronary artery spasm and documented ischaemic ventricular fibrillation with fortunate survival.

Thyroid emergencies

This review presents current knowledge about the thyroid emergencies known as myxedema coma and thyrotoxic storm. Understanding the pathogenesis of these conditions, appropriate recognition of the clinical signs and symptoms, and their prompt and accurate diagnosis and treatment are crucial in optimizing survival.

Graves' disease complicated by ventricular fibrillation in three men who were smokers

BACKGROUND

Thyrotoxicosis is known to be associated with sinus tachycardia and supraventricular tachyarrhythmias, but rarely with ventricular fibrillation (Vf), which has only occurred in some patients with hypokalemic periodic paralysis or ischemic heart disease.

PATIENT FINDINGS

We present three men who were transferred to our hospital with Graves' disease who developed idiopathic Vf. None of them had hypokalemic periodic paralysis or ischemic heart disease but all were smokers. None of other patients with thyrotoxicosis (587 females and 155 males) who were seen at our hospital, in the period during which the three men were seen, had idiopathic Vf. In our three men with thyrotoxicosis and idiopathic Vf, there was no identifiable underlying heart disease. One of the three patients died of hypoxic encephalopathy. The other two men did not have recurrent Vf after their thyroid function normalized.

SUMMARY

These cases and a review of similar cases in the literature imply that improving thyrotoxicosis seems to be effective for treating idiopathic Vf in some patients.

CONCLUSIONS

Our findings suggest that thyroid hormone excess might play a direct role in the development of Vf in susceptible individuals. Our experience with these three patients suggests that smoking men with thyrotoxicosis likely have an increased risk for Vf, even if they do not have other predisposing factors.

Thyroid storm with multiorgan failure

BACKGROUND

Thyroid storm is a rare and potentially fatal condition. Various unusual presentations in patients with thyroid storm have been described but multiorgan dysfunction is uncommonly seen.

SUMMARY

We describe a 35-year-old patient with a history of Graves' disease who was diagnosed with thyroid storm at 2 weeks postpartum. This was complicated by acute liver failure, acute kidney injury, severe lactic acidosis, disseminated intravascular coagulation, and heart failure with acute pulmonary edema. The multiorgan dysfunction was reversed by prompt institution of antithyroid drugs and supportive management in the intensive care unit.

CONCLUSION

Thyroid storm is a medical emergency. One of the challenges lies in recognizing its varied presentations. Early diagnosis and appropriate treatment is important to prevent the catastrophic outcomes associated with this condition.

Thyroid hormones and cardiac arrhythmias

Thyroid hormone plays an important role in cardiac electrophysiology and Ca2+ handling through both genomic and nongenomic mechanisms of action, while both actions can interfere. Chronic changes in the amount of circulating thyroid hormone due to thyroid dysfunction or systemic disease result in structural, electrophysiological and Ca2+ handling remodeling, while acute changes may affect basal activity of cardiac cells membrane systems. Consequently, long-term or rapid modulation of sarcolemmal ion channels, Ca2+ cycling proteins and intercellular communicating channels by thyroid hormone may affect heart function as well as susceptibility of the heart to arrhythmias. This aspect including pro- and anti-arrhythmic potential of thyroid hormone is highlighted in this review.

Thyrotoxicosis-induced ventricular arrhythmias

BACKGROUND

Cardiac arrhythmias associated with thyrotoxicosis tend to be supraventricular in nature with atrial fibrillation being the most common. Ventricular arrhythmias are rarely associated with thyrotoxicosis and are considered to be secondary to intrinsic cardiac disease.

SUMMARY

We present three patients with thyrotoxicosis and stable coronary disease in whom the primary cardiac rhythm disturbance was ventricular tachycardia. In all of these patients, the ventricular arrhythmias terminated with achievement of a euthyroid state. We hypothesize that the thyrotoxic state contributed to the etiology of, or lowered the threshold for the ventricular arrhythmias.

CONCLUSION

Prompt attention to the management of thyrotoxicosis in patients with a history of significant heart disease is warranted in order to avoid potentially fatal arrhythmias.

Recognizing thyroid storm in the neurologically impaired patient

Thyroid storm is a life-threatening complication of thyroid dysfunction that is manifested by signs of cardiac arrhythmias, fever, and neurological impairment. These symptoms can easily be attributed to a multitude of factors commonly seen in neurological intensive care units, making the recognition and diagnosis of this event difficult. In this case study, a patient presents with a complicated course of hospitalization exacerbated by thyroid storm. Early nursing care and medical collaboration offset a potentially fatal condition.

Incessant ventricular tachycardia due to subacute thyroiditis

Subacute thyroiditis is a possibly viral, inflammatory thyroid disorder which can cause thyrotoxicosis. Ventricular arrhythmias are uncommon in thyrotoxicosis and usually occur only in those with marked heart failure or associated cardiac disease. In this case, we present a 52-year-old woman having incessant ventricular tachycardia due to subacute thyroiditis without underlying cardiac disease.

Is it safe to treat hyperthyroid patients with I-131 without fear of thyroid storm?

OBJECTIVES

Thyroid storm is extremely rare. However, hyperthyroid patients with severe thyrotoxicosis are frequently not treated immediately with I-131 for fear of thyroid storm but are placed on thiouracil drugs for varying periods of time. We demonstrate herein that it is safe to treat these patients with 1-131, without pretreatment with thiouracil drugs, provided they do not have complicating intercurrent disease. Our definition of severe hyperthyroidism includes marked signs and symptoms of thyrotoxicosis, suppressed TSH, markedly elevated free T4 and/or free T3 and elevated radioactive iodine uptake (RAIU) (>30%) at 4 or 24 hours. Our diagnostic criteria for thyroid storm include two or more findings of fever (>38 degrees C, 100 degrees F), severe tachycardia, high pulse pressure, agitation with tremors, flushing, sweating, heart failure, nausea, vomiting, diarrhea, jaundice associated with high free T4 and/or free T3.

METHODS

Patients were selected retrospectively for the period between August 2003 and December 2004. One hundred and twenty-two patient visits were identified. These patients were treated with 370-740 MBq (10-20 mCi) of I-131 and were evaluated for any evidence of thyroid storm. Most of the patients were placed on beta blocker drugs at the time of initial I-131 therapy; these were continued for at least two months, when the first follow-up visit occurred. At the time of I-131 therapy, it is our policy to educate the patients to seek immediate medical attention for exacerbation of symptoms of thyrotoxicosis.

RESULTS

Not one of these patients developed thyroid storm. A subset of 25% of these cases with higher potential for thyroid storm (RAIU more than 65%, very marked signs and symptoms, and very markedly elevated free T4 and/or free T3) also tolerated the I-131 therapy well with marked clinical improvement and no exacerbation of the thyrotoxic state.

CONCLUSION

It is safe to administer I-131 to patients who are severely hyperthyroid without fear of thyroid storm, provided beta blockade drugs are used to control the signs and symptoms; patient education is also important. With these steps, 4-6 weeks of prior medical treatment may not be necessary.

Interferon treatment for hypereosinophilic syndromes and systemic mastocytosis

Hypereosinophilic syndromes (HES) and systemic mastocytosis (SMCD) are heterogeneous disorders with clinical symptoms from local and remote effects of excessive proliferation of eosinophils and mast cells, respectively. Interferon alpha (IFN-alpha), alone or in combination with other medications, can be a useful, and at times life-saving, treatment for patients with HES. Receptors for IFN-alpha are present on eosinophils, and clinical benefits are due to its effect on eosinophil proliferation, migration, activation, and survival. These effects are likely mediated through multiple pathways including, but not limited to, inhibition of eosinophil colony-forming cells, upregulation of IFN-gamma synthesis, and inhibition of production of eosinophil-active cytokines by T cells, mast cells, and mononuclear cells. IFN-alpha has been life-saving for patients with intractable HES that were resistant to prednisone, hydroxyurea, and other agents. Resistance to the eosinopenic effect of IFN-alpha does not develop and the dose of IFN-alpha necessary to maintain control of eosinophilia often decreases with time. The combination of IFN-alpha and hydroxyurea is very useful and allows dosage reduction of IFN-alpha and better control of hypereosinophilia than with either agent alone. The efficacy of IFN-alpha for treatment of SMCD has been more difficult to establish, with both favorable and unfavorable results reported. The disparate results may have resulted from the small number of patients with SMCD treated with IFN-alpha, the use of various criteria for a "successful" treatment outcome, short duration of treatment and follow-up, and the use of modest dosages. In reported series, side effects from IFN-alpha have frequently been dose-limiting. IFN-alpha improves many of the clinical symptoms of SMCD including dermatological, hematological, gastrointestinal, and systemic symptoms associated with histamine release. IFN-alpha has a beneficial effect on skeletal symptoms because of its ability to increase bone density and reduce painful episodes from vertebral fractures. No consistent improvement in bone marrow infiltration by mast cells has been demonstrated except in a recent study employing high dosages of IFN-alpha. A beneficial effect from the combination of IFN-alpha and prednisone has been reported for several patients, suggesting that combined use of these two medications may provide synergism in treatment outcomes.