Cardiac Autonomic Neuropathy in Graves' Disease: Smoking and Age as Predictive Factors

OBJECTIVES

Hypermetabolic state in Graves' disease (GD) has a great impact on heart homeostasis, acting directly on the heart muscle and modulating the autonomic nervous system. To characterize cardiac autonomic neuropathy (CAN) as a possible complication in patients with GD.

METHODS

We evaluated euthyroid GD patients and a control group of healthy euthyroid people. CAN was assessed using autonomic tests of cardiovascular reflex and heart rate variability: respiratory, Valsalva, orthostatic and orthostatic hypotension tests, high frequency, low frequency, and very low-frequency bands. Transthoracic echocardiography was performed in GD patients.

RESULTS

Sixty GD patients and 50 people in control group were assessed. CAN was diagnosed in 20% of GD and 14% in the control group. Among GD, 13.3% presented incipient, and 6.7% established CAN, while in the control group, it was verified incipient in 8% and established in 6% (P = .7479). All GD patients with CAN presented an alteration in the deep breathing test. Age and smoking were evidenced as factors associated with the presence of CAN, while higher TRAb values at diagnosis decreased the chance of CAN.

CONCLUSIONS

The prevalence of CAN in euthyroid GD patients was 20%. Changes in the cardiac autonomic nervous system were identified, pointing to the importance of evaluating this complication in these patients. Smoking was a predictive factor for CAN, increasing its relationship with conditions that aggravate GD.

Mechanisms and Management of Thyroid Disease and Atrial Fibrillation: Impact of Atrial Electrical Remodeling and Cardiac Fibrosis

Atrial fibrillation (AF) is the most common cardiac arrhythmia associated with increased cardiovascular morbidity and mortality. The pathophysiology of AF is characterized by electrical and structural remodeling occurring in the atrial myocardium. As a source of production of various hormones such as angiotensin-2, calcitonin, and atrial natriuretic peptide, the atria are a target for endocrine regulation. Studies have shown that disorders associated with endocrine dysregulation are potential underlying causes of AF. The thyroid gland is an endocrine organ that secretes three hormones: triiodothyronine (T3), thyroxine (T4) and calcitonin. Thyroid dysregulation affects the cardiovascular system. Although there is a well-established relationship between thyroid disease (especially hyperthyroidism) and AF, the underlying biochemical mechanisms leading to atrial fibrosis and atrial arrhythmias are poorly understood in thyrotoxicosis. Various animal models and cellular studies demonstrated that thyroid hormones are involved in promoting AF substrate. This review explores the recent clinical and experimental evidence of the association between thyroid disease and AF. We highlight the current knowledge on the potential mechanisms underlying the pathophysiological impact of thyroid hormones T3 and T4 dysregulation, in the development of the atrial arrhythmogenic substrate. Finally, we review the available therapeutic strategies to treat AF in the context of thyroid disease.

Outcomes of Graves' Disease Patients Following Antithyroid Drugs, Radioactive Iodine, or Thyroidectomy as the First-line Treatment

BACKGROUND

The long-term outcomes of first-line choice among ATD, RAI, and thyroidectomy for GD patients remain unclear.

OBJECTIVE

To compare the long-term morbidity, mortality, relapse, and costs of GD patients receiving first-line treatment.

METHODS

A population-based retrospective cohort of GD patients initiating first-line treatment with ATD, RAI, or thyroidectomy as a first-line primary treatment between 2006 and 2018 from Hong Kong Hospital Authority was analyzed. Risks of all-cause mortality, CVD, AF, psychological disease, diabetes, and hypertension were estimated using Cox proportional hazards regression models. The 10-year healthcare costs, change of comorbidities, and risk of relapse were compared across treatments.

RESULTS

Over a median follow-up of 90 months with 47,470 person-years, 6385 patients (ATD, 74.93%; RAI, 19.95%; thyroidectomy, 5.12%) who received first-line treatment for GD were analyzed. Compared with ATD group, patients who had undergone surgery had significantly lower risks of all-cause mortality [hazard ratio (HR) = 0.363, 95% confidence interval (CI) = 0.332-0.396], CVD (HR = 0.216, 95% CI = 0.195-0.239), AF (HR = 0.103, 95% CI = 0.085-0.124), psychological disease (HR = 0.279, 95% CI = 0.258-0.301), diabetes (HR = 0.341, 95% CI = 0.305-0.381), and hypertension (HR = 0.673, 95% CI = 0.632-0.718). Meanwhile, RAI group was also associated with decreased risks of all-cause mortality (HR = 0.931, 95% CI = 0.882-0.982), CVD (HR = 0.784, 95% CI = 0.742-0.828), AF (HR = 0.622, 95% CI = 0.578-0.67), and psychological disease (HR = 0.895, 95% CI = 0.855-0.937). The relapse rate was 2.41% in surgery, 75.60% in ATD, and 19.53% in RAI group. The surgery group was observed with a significant lower Charlson Comorbidity Index score than the other 2 groups at the tenth-year follow-up. The mean 10-year cumulative healthcare costs in ATD, RAI, and surgery group was US$23915, US$24260, and US$20202, respectively.

CONCLUSIONS

GD patients who received surgery as an initial treatment appeared to have lower chances of all-cause mortality, CVD, AF, psychological disease, diabetes, and hypertension in the long-term when compared to those treated with ATD or RAI. The surgery group had the lowest relapse and direct healthcare costs among the 3 treatment modalities. This long-term cohort study suggested surgery may have a larger role to play as an initial treatment for GD patients.

Orbital inflammatory disorders: new knowledge, future challenges

PURPOSE OF REVIEW

This review aims to bring together recent advances in basic, translational and clinical research on the pathogenesis and treatment of orbital inflammatory conditions.

RECENT FINDINGS

Basic science studies provide mechanistic insights into why the orbit is targeted for inflammation by autoimmune inflammatory disorders. Using Graves' disease as a test case reveals that endocrine pathways, such as the TSH and IGF1 receptor pathways play important roles in stimulating orbital inflammation. Furthermore, orbital tissues contain high concentrations of retinoids - byproducts of the visual pathway that diffuse across the sclera and can activate de novo transcription of inflammatory cytokines. Such cytokine expression places the orbit in a hyper-inflammatory 'resting' state, prone to respond to any additional systemic or local pro-inflammatory signals. The HIF2A--LOX pathway appears important for orbital tissue fibrosis. Lastly, bench-to-bedside studies of the IGF1R pathway have led to an FDA-approved drug, teprotumumab that represents a novel treatment approach for Graves' orbitopathy. Unfortunately, high drug costs and misplaced insurance company 'step-therapy' policies may block patients from receiving therapy that can protect vision and improve quality of life.

SUMMARY

Improved understanding of orbital inflammatory conditions has led to a new drug and promises additional breakthroughs. Translational research is successful, but requires time, resources, and patience.

Comparison of 24-Hour Electrocardiogram Parameters in Patients with Graves' Disease Before and After Anti-Thyroid Therapy

BACKGROUND

We aimed prospectively to investigate the laboratory and electrocardiographic parameters (heart rate, QRS, QT, QTc, Tpe, Tpe/QTc, and arrhythmia prevalence) in patients with Graves' disease before and after antithyroid therapy.

METHODS

Seventy-one patients (48 female, and 23 male), of age between 18-50 years (mean±SD: 36.48±12.20) with GD were included in the study. Patients were treated with antithyroid therapy (thioamides and/or surgical therapy) to maintain euthyroid status. Patients were examined in terms of electrocardiographic parameters before and after the treatment.

RESULTS

Mean TSH, free thyroxin (fT4), and tri-iodothyrionine (fT₃) levels of all patients were 0.005±0.21, 3.27± 1.81, 11.42±7.44, respectively. While 9 patients (group 2) underwent surgical therapy, had suspicious malignant nodule or large goiter, and unresponsiveness to medical treatment; the other patients (n=62, group 1) were treated with medical therapy. Patients with surgical therapy had more increased serum fT4 (p=0.045), anti-thyroglobulin value (p=0.018) and more severe graves orbitopathy (n=0.051) before treatment when compared to a medical therapy group. Baseline Tpe duration and baseline Tpe/QTc ratio and frequency of supraventricular ectopic beats were found to be significantly higher in group 2 when compared to group 1 (p=0.00, p=0.005). Otherwise, the baseline mean heart rate, QRS duration, QTc values of both groups were similar. Although the patients came at their euthyroid status, group 2 patients still suffered from more sustained supraventricular ectopics beats than group 1.

CONCLUSION

Distinct from the medical treatment group, surgical treatment group with euthyroidism for at least 3 months still suffered from an arrhythmia (Tpe, Tpe/QTc, supraventricular and ventricular ectopic beats).

Racial disparities in comorbid conditions among patients undergoing thyroidectomy for Graves' disease: An ACS-NSQIP analysis

BACKGROUND

Studies indicate that racial disparities exist in the presentation and outcomes of patients undergoing thyroidectomy for cancer and benign disease. We examined the relationship between race, pre-operative characteristics and outcomes in patients undergoing thyroidectomy for GD.

METHODS

Patients were identified from the 2013-2016 American College of Surgeons NSQIP database using ICD-9/10 codes consistent with diffuse toxic goiter.

RESULTS

AA patients were more likely to have an ASA classification of ≥3 (41% vs 30%, p < 0.001), a higher rate of CHF (2.1% vs 0.5%, p = 0.01), hypertension (46% vs 32%, p < 0.001) and dyspnea (10% vs 5%, p < 0.001) compared to Non-Hispanic Caucasians (NH-C) patients. Complications were higher in patients with ASA≥3 and CHF but not affected by race.

CONCLUSIONS

Analysis of a national database of thyroidectomy for GD revealed a higher burden of preoperative comorbidities in AA patients compared to other races, although race was not an independent predictor of outcomes.

Impact of surgery versus medical management on cardiovascular manifestations in Graves disease

BACKGROUND

Graves disease is well known to have multiple adverse effects on the cardiovascular system. We compared the cardiovascular outcomes after surgical intervention versus medical treatment in patients with Graves disease.

METHODS

We performed a retrospective study of all Graves disease patients with a cardiovascular comorbidity who underwent either surgical or medical management (N = 151). Perioperative biochemical and cardiovascular outcomes from the surgical versus the medical groups were analyzed.

RESULTS

Of 151 patients, 69 (45.6%) patients underwent total thyroidectomy and 82 (54.3%) patients received medical treatment. Hypertension resolved in 44.7% of the patients from the surgical group vs 18% in the medical group (P = .03). Tachyarrhythmias, including atrial fibrillation and tachycardia, improved in 85.9% of patients in the surgical group vs 66% in the medical group (P = .01). All cardiovascular manifestations examined, hypertension, tachyarrhythmias, and heart failure, improved in 69% of patients in the surgical group and 42.6% of patients in the medical group during the follow-up period (P < .01).

CONCLUSION

Surgical treatment offers a significant and rapid clinical improvement of cardiovascular manifestations in Graves disease patients, such as hypertension, tachyarrhythmias, and heart failure. Surgery should be considered and recommended in Graves disease patients with known cardiovascular manifestations.

Pro-Arrhythmic Signaling of Thyroid Hormones and Its Relevance in Subclinical Hyperthyroidism

A perennial task is to prevent the occurrence and/or recurrence of most frequent or life-threatening cardiac arrhythmias such as atrial fibrillation (AF) and ventricular fibrillation (VF). VF may be lethal in cases without an implantable cardioverter defibrillator or with failure of this device. Incidences of AF, even the asymptomatic ones, jeopardize the patient's life due to its complication, notably the high risk of embolic stroke. Therefore, there has been a growing interest in subclinical AF screening and searching for novel electrophysiological and molecular markers. Considering the worldwide increase in cases of thyroid dysfunction and diseases, including thyroid carcinoma, we aimed to explore the implication of thyroid hormones in pro-arrhythmic signaling in the pathophysiological setting. The present review provides updated information about the impact of altered thyroid status on both the occurrence and recurrence of cardiac arrhythmias, predominantly AF. Moreover, it emphasizes the importance of both thyroid status monitoring and AF screening in the general population, as well as in patients with thyroid dysfunction and malignancies. Real-world data on early AF identification in relation to thyroid function are scarce. Even though symptomatic AF is rare in patients with thyroid malignancies, who are under thyroid suppressive therapy, clinicians should be aware of potential interaction with asymptomatic AF. It may prevent adverse consequences and improve the quality of life. This issue may be challenging for an updated registry of AF in clinical practice. Thyroid hormones should be considered a biomarker for cardiac arrhythmias screening and their tailored management because of their multifaceted cellular actions.

Cardiac Arrhythmias in Autoimmune Diseases

Autoimmune diseases (ADs) affect approximately 10% of the world's population. Because ADs are frequently systemic disorders, cardiac involvement is common. In this review we focus on typical arrhythmias and their pathogenesis, arrhythmia-associated mortality, and possible treatment options among selected ADs (sarcoidosis, systemic lupus erythematosus, scleroderma, type 1 diabetes, Graves' disease, rheumatoid arthritis, ankylosing spondylitis [AS], psoriasis, celiac disease [CD], and inflammatory bowel disease [IBD]). Rhythm disorders have different underlying pathophysiologies; myocardial inflammation and fibrosis seem to be the most important factors. Inflammatory processes and oxidative stress lead to cardiomyocyte necrosis, with subsequent electrical and structural remodeling. Furthermore, chronic inflammation is the pathophysiological basis linking AD to autonomic dysfunction, including sympathetic overactivation and a decline in parasympathetic function. Autoantibody-mediated inhibitory effects of cellular events (i.e., potassium or L-type calcium currents, M₂muscarinic cholinergic or β₁-adrenergic receptor signaling) can also lead to cardiac arrhythmia. Drug-induced arrhythmias, caused, for example, by corticosteroids, methotrexate, chloroquine, are also observed among AD patients. The most common arrhythmia in most AD presentations is atrial arrhythmia (primarily atrial fibrillation), expect for sarcoidosis and scleroderma, which are characterized by a higher burden of ventricular arrhythmia. Arrhythmia-associated mortality is highest among patients with sarcoidosis and lowest among those with AS; there are scant data related to mortality in patients with psoriasis, CD, and IBD.

Significant cardiac disease complicating Graves' disease in previously healthy young adults

SUMMARY

Graves' disease is associated with tachydysrythmia, cardiac ischaemia and cardiomyopathy - all uncommon in young adults without previous cardiac disease. We present three young individuals who developed cardiac complications after periods of uncontrolled Graves' disease. Subject 1: A 34-year-old female had severe thyrotoxic symptoms for weeks. Investigations showed fT4: 98.4 (11-25 pmol/L), fT3: 46.9 (3.1-6.8 pmol/L), TSH <0.01 (0.27-4.2 mU/L) and thyrotrophin receptor antibody (TRAb): 34.8 (<0.9 U//l). She had appropriate treatment but several weeks later she became breathless despite improving thyroid function. Echocardiography showed a pericardial effusion of 2.9 cm. She responded well to steroids and NSAIDs but developed active severe Graves' orbitopathy after early total thyroidectomy. Subject 2: A 28-year-old male developed thyrotoxic symptoms (fT4: 38 pmol/L, fT3: 13.9 pmol/L, TSH <0.01 (for over 6 months) and TRAb: 9.3 U/L). One month after starting carbimazole, he developed acute heart failure (HF) due to severe dilated cardiomyopathy - EF 10-15%. He partially recovered after treatment - EF 28% and had early radioiodine treatment. Subject 3: A 42-year-old woman who had been thyrotoxic for several months (fT4: 54.3; fT3 >46.1; TSH <0.01; TRAb: 4.5) developed atrial fibrillation (AF) and heart failure. Echocardiography showed cardiomegaly - EF 29%. She maintains sinus rhythm following early total thyroidectomy (EF 50%). Significant cardiac complications may occur in previously fit young adults, who have had uncontrolled Graves' disease for weeks to months. Cardiac function recovers in the majority, but early definitive treatment should be discussed to avoid Graves' disease relapse and further cardiac decompensation.

LEARNING POINTS

Cardiac complications of Graves' disease are uncommon in young adults without previous cardiac disease. These complications may however occur if Graves' disease had been poorly controlled for several weeks or months prior to presentation. Persistent symptoms after adequate control should alert clinicians to the possibility of cardiac disease. Specific treatment of Graves' disease and appropriate cardiac intervention results in complete recovery in the majority and carries a good prognosis. Early definitive treatment should be offered to them to prevent cardiac decompensation at times of further relapse.