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

Translation of pathophysiological mechanisms of atrial fibrosis into new diagnostic and therapeutic approaches

Atrial fibrosis is one of the main manifestations of atrial cardiomyopathy, an array of electrical, mechanical and structural alterations associated with atrial fibrillation (AF), stroke and heart failure. Atrial fibrosis can be both a cause and a consequence of AF and, once present, it accelerates the progression of AF. The pathophysiological mechanisms leading to atrial fibrosis are diverse and include stretch-induced activation of fibroblasts, systemic inflammatory processes, activation of coagulation factors and fibrofatty infiltrations. Importantly, atrial fibrosis can occur in different forms, such as reactive and replacement fibrosis. The diversity of atrial fibrosis mechanisms and patterns depends on sex, age and comorbidity profile, hampering the development of therapeutic strategies. In addition, the presence and severity of comorbidities often change over time, potentially causing temporal changes in the mechanisms underlying atrial fibrosis development. This Review summarizes the latest knowledge on the molecular and cellular mechanisms of atrial fibrosis, its association with comorbidities and the sex-related differences. We describe how the various patterns of atrial fibrosis translate into electrophysiological mechanisms that promote AF, and critically appraise the clinical applicability and limitations of diagnostic tools to quantify atrial fibrosis. Finally, we provide an overview of the newest therapeutic interventions under development and discuss relevant knowledge gaps related to the association between clinical manifestations and pathological mechanisms of atrial fibrosis and to the translation of this knowledge to a clinical setting.

Mediating role of blood metabolites in the relationship between arrhythmia and hyperthyroidism in East Asian populations

BACKGROUND AND AIM

Arrhythmia is a common manifestation of hyperthyroidism, and blood metabolites may play a regulatory role in cardiovascular health and thyroid function. However, the mediating role of blood metabolites between arrhythmia and hyperthyroidism, particularly in East Asian populations, remains unclear.

METHODS AND RESULTS

We used large-scale GWAS data from East Asian populations for a two-step Mendelian randomization (MR) analysis. First, we assessed the causal link between arrhythmia and hyperthyroidism, then evaluated the mediating role of blood metabolites. GWAS data on arrhythmia, hyperthyroidism, and metabolites were used. Mediation effects were calculated, and sensitivity analyses ensured robustness. The inverse-variance weighted (IVW) method was the primary tool, while colocalization analysis assessed shared genetic loci, confirming if the genetic signals for these traits arise from the same variants. The analysis revealed a significant association between arrhythmia and increased hyperthyroidism risk (OR = 1.272, p = 0.003), and reverse MR confirmed a positive association (OR = 1.039, p = 0.036), indicating a bidirectional link. Sensitivity analyses using weighted median, simple mode, and weighted mode provided consistent results. Blood urea nitrogen was identified as a key mediator, explaining 9.7 % of the causal relationship between arrhythmia and hyperthyroidism. These findings were unaffected by heterogeneity or pleiotropy.

CONCLUSIONS

Blood urea nitrogen is a novel mediator in the arrhythmia-hyperthyroidism relationship, highlighting its potential role in cardiovascular and thyroid health.

Evaluating cardiac electrophysiological markers for predicting arrhythmic risk in hypothyroid patients

OBJECTIVES

This study aimed to evaluate the impact of hypothyroidism and levothyroxine (LT4) treatment on arrhythmic risk by concurrently analyzing multiple electrocardiogram (ECG) parameters such as the Index of Cardio-Electrophysiological Balance (iCEB), frontal QRS-T angle, Tpeak-Tend (Tp-e) interval/QT interval ratio, and QT dispersion (QTd).

METHODS

This cross-sectional study included 132 adult patients with primary hypothyroidism who had been receiving LT4 treatment, and 132 demographically matched healthy controls. The hypothyroid group was also stratified by thyroid-stimulating hormone (TSH) levels (subclinical <4.5 and overt ≥ 4.5). Participants underwent a series of thyroid function and ECG measurements.

RESULTS

The hypothyroid and healthy control groups were matched for age and gender (p = 0.080; p = 0.176). Participants with hypothyroidism had higher Tp-e/QT ratios, iCEB, median frontal QRS-T angle, and corrected QT dispersion (cQTd) than healthy controls (p = 0.004; p = 0.025; p = 0.004; p = 0.004, respectively). In the overt group, the Tp-e/QT ratio, iCEB, and median frontal QRS-T angles were all higher (p = 0.012, p = 0.037, and p = 0.016, respectively). Logistic regression analysis indicated that a higher iCEB score (β = 0.60, p = 0.003) was significant for the detection of arrhythmia risk. ROC analysis showed that iCEB had the highest sensitivity (0.80), moderate specificity (0.60), and AUC 0.70.

CONCLUSION

Patients with hypothyroidism have a higher risk of arrhythmia. To assess this risk, it is important to analyze the Tp-e interval, iCEB, frontal QRS-T angle, and QTd. Differentiating between patients with subclinical and overt hypothyroidism can help minimize the risk of arrhythmia. iCEB is the most effective method for identifying arrhythmic risk. Using all these parameters can improve the accuracy of arrhythmic risk detection in patients with hypothyroidism.

[Changes of the Heart Rhythm in Imbalance of Thyroid Gland Hormones and its Morphology in Outbred Rats]

AIM

To analyze the relationship between the occurrence of atrial fibrillation (AF) and thyroid dysfunction caused by low concentrations of free triiodothyronine (FT3), free triiodothyronine and free thyroxine (FT3 and FT4), and high concentrations of free thyroxine (FT4) with normal values of thyroid-stimulating hormone (TSH) in experiments on outbred rats.

MATERIAL AND METHODS

The pathogenesis of AF with low concentrations of FT3, FT3 and FT4, and a high concentration of FT4 was studied in an experiment on 146 outbred rats. In the experiment, hypothyroidism, euthyroidism, and thyrotoxicosis were modeled by changing the concentrations of thyroid hormones, and the effect of these conditions on ECG and the incidence of AF was evaluated.

RESULTS

The types of the hypothalamic-pituitary-thyroid system response to the L-thyroxine administration in experimental hypothyroidism were identified. A relationship was determined between AF paroxysms and threshold values of thyroid hormones at low concentrations of FT3, FT3 and FT4, and a high concentration of FT4 with normal TSH values. It was shown that achieving the euthyroid status did not reduce the incidence of AF paroxysms by more than 70.0%.

CONCLUSION

In AF with low FT3, low FT3 and FT4, and high FT4, the dose of L-thyroxine must be adjusted.

Thyroid dysfunction in nonvalvular atrial fibrillation and clinical outcomes

BACKGROUND

Thyroid dysfunction's effects on those who have been diagnosed with atrial fibrillation have not been well investigated. We looked at how thyroid function among patients with pre-existing atrial fibrillation related to thromboembolic risk and clinical outcomes.

METHODS

We gathered the medical information of patients diagnosed with nonvalvular atrial fibrillation (NVAF) between 2016 and 2020 at Dongguan People's Hospital. We then assessed the correlation between thyroid dysfunction and thrombotic risk (CHA2DS2-VASc) as well as the occurrence of clinical composite endpoint (all-cause death, heart failure, systemic embolism and hemorrhage events).

RESULTS

Of 1329 patients were admitted, 82.6% were euthyroid, 7.4% had subclinical hyperthyroidism, 4.2% had subclinical hypothyroidism, and 6.7% had low triiodothyronine (T3) syndrome. Lower levels of total triiodothyronine (TT3) were linked to an increased risk of thromboembolism (P < 0.005). During a median follow-up period of 1.84 years, there were 608 clinical composite endpoint occurrences. In the adjusted model, Low T3 syndrome was linked to a higher risk of the clinical composite endpoint (HR, 1.68; 95% CI, 1.20-2.37; P < 0.05) in comparison to euthyroidism. Specifically, low T3 syndrome was linked to a higher risk of heart failure (HR, 1.52; 95%CI, 1.01-2.30; P < 0.05) and all-cause death (HR, 3.34; 95% CI, 1.76-6.36; P < 0.001).

CONCLUSION

Low T3 syndrome are linked to an increased risk of heart failure and all-cause death in individuals with NVAF. And Patients with NVAF and low TT3 levels have a higher risk of thromboembolism.

Effects of atrial fibrillation screening according to thyroid function: Post-hoc analysis of the randomized LOOP study

PURPOSE

Subclinical thyroid dysfunction is a marker for atrial fibrillation (AF) and stroke risk. This study explored the effects of AF screening according to thyroid-stimulating hormone (TSH) levels.

METHODS

An AF screening trial (the LOOP study) was analyzed post-hoc according to baseline TSH. The primary outcome was stroke or systemic embolism (SE). Secondary outcomes included major bleeding, all-cause death, and the combination of stroke, SE, and cardiovascular death.

RESULTS

TSH measurement was available in 6003 of 6004 trial participants, 1500 randomized to implantable loop recorder (ILR) screening for AF and anticoagulation upon detection vs. 4503 to usual care; mean age was 74.7±4.1 years and 2836 (47%) were women. AF detection was approximately triple for ILR vs usual care across TSH tertiles (adjusted p-interaction=0.44). In the first tertile, screening was associated with decreased risk of the primary outcome (hazard ratio 0.52 [0.30-0.90]; p=0.02) and stroke, SE, or cardiovascular death (hazard ratio 0.54 [0.34-0.84]; p=0.006) compared to usual care, while no effect was observed among participants with higher TSH (adjusted p-interaction 0.03 and 0.01, respectively). There was no effect on other outcomes. Analyses of continuous TSH or excluding those with abnormal TSH or thyroid medication showed similar results.

CONCLUSION

AF screening and subsequent treatment was associated with decreased stroke risk among participants with low TSH, though the yield of screening was similar across TSH levels. TSH may be useful as a marker to indicate benefit from AF screening vs. overdiagnosis and overtreatment. These findings should be considered exploratory and warrant further study.

TRIAL REGISTRATION

ClinicalTrials.gov, identifier: NCT0203645.

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.

[Arrhythmias in thyroid dysfunction]

Thyroid dysfunction is associated with characteristic changes in heart rate and arrhythmias. Thyroid hormones act through genomic and non-genomic effects on myocytes and influence contractility, relaxation and action potential duration through a variety of mechanisms. Atrial fibrillation is the most common arrhythmia associated with thyroid dysfunction, it occurs in both euthyroidism and hyperthyroidism in clear association with T4 levels. Mechanistically, in the hyperthyroid state, increased automaticity and triggered activity, together with a shortened refractory period and slowing of the conduction speed, lead to the initiation and maintenance of multiple intraatrial reentry circuits. Influences from the autonomic nervous system and hemodynamics controlled by thyroid hormones act as modulators for arrhythmias, which are promoted by a corresponding substrate (significant impact of comorbidities). Concerning therapy, in addition to treating hyperthyroidism, the initial therapeutic focus is on adequate rate control and anticoagulation in patients with a high risk of thromboembolism. Ablation of atrial fibrillation can be considered later on, although there is an increased likelihood of recurrence compared to patients without hyperthyroidism.Prolongation of the QT interval and increase in QT dispersion are involved in the formation of ventricular arrhythmias. Epidemiological data suggest an association of elevated T4 levels with ventricular arrhythmias and sudden cardiac death. However, this seems to be mainly relevant for patients with underlying cardiac disease (e.g. ICD users).

Cardiac Electrical and Structural Changes after Iodinated Contrast Media Administration: A Longitudinal Cohort Analysis

Background: Iodinated contrast is commonly used for radiological procedures, with one dose delivering several hundred-fold the daily requirements needed for normal thyroid hormone production. Risks of excess iodine include incident thyroid dysfunction, which is associated with adverse cardiac outcomes, yet there are no prospective studies investigating the changes in cardiac physiology following iodine contrast administration. This study was conducted to investigate the longitudinal relationships between the amount of iodinated contrast administration and changes in cardiac electrophysiology and structure. Methods: A longitudinal cohort study was conducted with prospectively enrolled participants who received iodine contrast for elective computed tomography or coronary angiography. Serum thyroid function tests, electrocardiograms (EKG), and transthoracic echocardiograms were obtained serially until 36 months. Trends of electrical and structural cardiac changes following iodine contrast administration were assessed using mixed effect models. Results: The cohort was composed of 129 patients (median age, 70 [interquartile range: 63, 75] years; 98% male). Larger amounts of iodine exposure were associated with increases in QRS and QTc durations and decreased ejection fraction (EF), and these associations were still observed for follow-up EF after additionally adjusting for baseline values (the high-iodine contrast group vs. the low-iodine contrast group, -4.23% [confidence interval, -7.66% to -0.79%]). Dose-response analyses also showed lower EF with larger amounts of iodine received; these trends were not significant for the EKG parameters studied. Conclusions: Over a period of up to 36 months, a larger amount of administered iodine contrast was associated with lower EF among participants. Further investigation is needed to elucidate the long-term trends of electrical and structural cardiac function after iodine contrast administration.

Multidisciplinary Approach in Atrial Fibrillation: As Good as Gold

Atrial fibrillation (AF) represents the most common sustained arrhythmia necessitating dual focus: acute complication management and sustained longitudinal oversight to modulate disease progression and ensure comprehensive patient care over time. AF is a multifaceted disorder; due to such a great number of potential exacerbating conditions, a multidisciplinary team (MDT) should manage AF patients by cooperating with a cardiologist. Effective management of AF patients necessitates the implementation of a well-coordinated and tailored care pathway aimed at delivering optimized treatment through collaboration among various healthcare professionals. Management of AF should be carefully evaluated and mutually agreed upon in consultation with healthcare providers. It is crucial to recognize that treatment may evolve due to the emergence of new risk factors, symptoms, disease progression, and advancements in treatment modalities. In the context of multidisciplinary AF teams, a coordinated approach involves assembling a diverse team tailored to meet individual patients' unique needs based on local services' availability.

Unusual Presentations of Thyrotoxic Tricuspid and Mitral Regurgitations in 62 Adults: A Systematic Review of Case Reports with In-depth Pathophysiological Review

Background

Thyrotoxicosis is related to cardiovascular mortality. This can be caused by several clinical manifestations involving the rare provocation of tricuspid regurgitation (TR) and mitral regurgitation (MR). However, there are still no clear data on thyrotoxic TR and/or MR. This study examines the progression of TR, MR, heart failure (HF) and pulmonary hypertension (PH) in response to the thyrotoxic heart manifestations, clinical characteristics and treatment approaches.

Methods

A PRISMA-based systematic search was conducted using PubMed and other databases up to 17 June 2023. The outcomes of this study were TR, MR, HF and PH with their progression on follow-up, clinical characteristics and treatment approaches.

Results

A total of 57 case reports involving 62 patients (45.77 ± 13.41 years) were included in this study. They were predominantly women (n=50; 80.65%) and diagnosed with Graves' disease (n=41; 75.81%). All patients were diagnosed with thyrotoxicosis, and this included 23 (37.10%) cases of thyroid storm. From echocardiographic studies, several patients improved clinically within the first 6 months of follow-up, including 20 TR patients (83.33%) in 6 months, nine MR patients (69.23%) in 3 months, eight HF patients (66.67%) in 2 months and 16 PH patients (76.19%) in 6 months.

Conclusion

Several mechanisms are involved in thyrotoxic TR and/or MR, including the direct thyroid hormone effect and the indirect effect of other hyperthyroidism-associated factors. Patients with thyrotoxic TR and/or MR, including those with HF and PH, can experience clinical and structural improvements following hyperthyroidism treatment in the first 6 months.

Cardiometabolic Risk Factors Related to Atrial Fibrillation and Metabolic Syndrome in the Pakistani Population

Background and Objectives: This study aimed to examine the relationship between cardiometabolic risk factors and atrial fibrillation (AF) and the simultaneous presence of AF and metabolic syndrome (MetS) in the Pakistani population. Materials and Methods: A total of 690 subjects were enrolled (n = 230 patients with AF, n = 230 patients with AF and MetS, and n = 230 controls). The associations between cardiometabolic parameters and AF with and without MetS were analyzed by univariable and multivariable binary regression analyses. Results: Body mass index (BMI), fasting blood glucose (FBG), and triglycerides (TG) were independently positively correlated, but the glomerular filtration rate (GFR) and sodium were independently negatively correlated with AF. An increase in BMI, FBG, and TG levels by one unit measure increased the probability by 55.1%, 20.6%, and 1.3%, respectively, for the AF occurrence. A decrease in GFR and sodium levels increased the probability by 4.3% and 33.6%, respectively, for the AF occurrence. On the other hand, uric acid was independently negatively correlated, whereas sodium was independently positively correlated, with MetS and AF. A decrease in uric acid levels and an increase in sodium levels by 1 unit measure increased the probability for MetS and AF by 23.2% and 7.5%, respectively. Conclusions: Cost-effective and routinely measured parameters, i.e., BMI, FBG TG, GFR, and sodium levels, can be reliable indicators of AF, whereas serum uric acid and sodium levels are independently associated with AF and MetS in the Pakistani population. Timely recognition and the control of modifiable cardiometabolic risk factors are of great significance in the prevention of AF development.

Long-term Effect of Thyrotropin-binding Inhibitor Immunoglobulin on Atrial Fibrillation in Euthyroid Patients

OBJECTIVE

Individuals with hyperthyroidism are at an increased risk of atrial fibrillation (AF), but the association between autoantibodies and AF or cardiovascular mortality in individuals who have returned to normal thyroid function remains unclear.

METHODS

The study utilized electronic medical records from National Taiwan University Hospital between 2000 and 2022. Each hyperthyroidism patient had at least 1 thyrotropin-binding inhibiting immunoglobulin (TBII) measurement. The relationship between TBII levels and the risk of AF and cardiovascular mortality was assessed using multivariable Cox regression models and Kaplan-Meier survival analysis.

RESULTS

Among the 14 618 enrolled patients over a 20-year timeframe, 173 individuals developed AF, while 46 experienced cardiovascular mortality. TBII values exceeding 35% were significantly associated with an elevated risk of AF for both the first TBII (hazard ratio {HR} 1.48 [1.05-2.08], P = .027) and mean TBII (HR 1.91 [1.37-2.65], P < .001). Furthermore, after free T4 levels had normalized, a borderline association between first TBII and AF (HR 1.59 [0.99-2.56], P = .056) was observed, while higher mean TBII increased AF (HR 1.78 [1.11-2.85], P = .017). Higher first and mean TBII burden continued to significantly impact the incidence of cardiovascular mortality (HR 6.73 [1.42-31.82], P = .016; 7.87 [1.66-37.20], P = .009). Kaplan-Meier analysis demonstrated that elevated TBII levels increased the risk of AF and cardiac mortality (log-rank P = .035 and .027, respectively).

CONCLUSION

In euthyroid individuals following antithyroid treatment, elevated circulating TBII levels and burden are associated with an elevated risk of long-term incident AF and cardiovascular mortality. Further reduction of TBII level below 35% will benefit to clinical outcomes.

Reversible acute heart failure induced by thyrotoxic cardiomyopathy: A case report

RATIONALE

Thyrotoxic cardiomyopathy is a rare but severe complication of thyrotoxicosis, leading to episodes of acute heart failure. This case report highlights a rare presentation of thyrotoxic cardiomyopathy with low-output heart failure, emphasizing the importance of early diagnosis and comprehensive management. The report aims to increase awareness among clinicians about the potential reversibility of this condition and the effective strategies for managing such complex cases.

PATIENT CONCERNS

This patient presented with dyspnea and chest constriction, without any antecedent predisposing factors. Subsequently, the patient abruptly manifested symptoms indicative of acute heart failure during outpatient consultation. Electrocardiography revealed rapid atrial fibrillation with type A preexcitation syndrome, whereas cardiac ultrasonography demonstrated global cardiac enlargement with a diminished ejection fraction (EF).

DIAGNOSES

After a comprehensive evaluation, the patient was diagnosed with thyrotoxic cardiomyopathy, acute heart failure, and atrial fibrillation with preexcitation syndrome.

INTERVENTIONS

Immediate interventions comprised diuretic administration, oxygen therapy, and antiarrhythmic agents, addressing acute heart failure concomitant with preexcitation syndrome. Following a fortnight of comprehensive therapeutic measures, the patient was discharged with a prescription for oral medications, notably methimazole.

OUTCOMES

Following the intervention, the patient showed significant improvement with the resolution of heart failure symptoms and dyspnea, restoration of sinus rhythm, improved left ventricular ejection fraction (LVEF improved from 36% to 45%), and normalization of thyroid function. These outcomes underscore the efficacy of the intervention strategy and offer a hopeful prognosis for similar cases.

LESSONS

Thyrotoxicosis may cause cardiomyopathy in patients with heart failure that manifests as dilated cardiac chambers. Clinicians should carefully screen patients for this reversible condition. Diagnosis requires a comprehensive assessment of various tests, and the therapeutic goal is to restore normal thyroid function.

Deciphering the roles of triiodothyronine (T3) and thyroid-stimulating hormone (TSH) on cardiac electrical remodeling in clinical and experimental hypothyroidism

Hypothyroidism is the most frequent endocrine pathology. Although clinical or overt hypothyroidism has been traditionally associated to low T3 / T4 and high thyrotropin (TSH) circulating levels, other forms exist such as subclinical hypothyroidism, characterized by normal blood T3 / T4 and high TSH. In its different forms is estimated to affect approximately 10% of the population, especially women, in a 5:1 ratio with respect to men. Among its consequences are alterations in cardiac electrical activity, especially in the repolarization phase, which is accompanied by an increased susceptibility to cardiac arrhythmias. Although these alterations have traditionally been attributed to thyroid hormone deficiency, recent studies, both clinical trials and experimental models, demonstrate a fundamental role of TSH in cardiac electrical remodeling. Thus, both metabolic thyroid hormones and TSH regulate cardiac ion channel expression in many and varied ways. This means that the different combinations of hormones that predominate in different types of hypothyroidism (overt, subclinic, primary, central) can generate different forms of cardiac electrical remodeling. These new findings are raising the relevant question of whether serum TSH reference ranges should be redefined.

Thyroid Disorders and Peripheral Arterial Disease

Hypothyroidism and hyperthyroidism, both overt and subclinical, are associated with increased risk of cardiovascular morbidity and mortality. The association between thyroid-stimulating hormone levels and cardiovascular risk has been demonstrated in large epidemiological studies and meta-analyses and is now considered a U-shaped curve. Several pathophysiological mechanisms linking thyroid and cardiovascular disease are known; however, specific clinical complications of peripheral arterial disease as endpoints of clinical trials have not been adequately investigated. The potential mechanisms linking hypothyroidism and peripheral arterial disease are endothelial dysfunction, blood pressure changes, dyslipidemia, and low-grade systemic inflammation. The potential mechanisms linking hyperthyroidism and peripheral arterial disease are hyperdynamic circulation, elevated systolic blood pressure, hypercoagulability, and possibly increased arterial inflammation.

Correlation between serum uric acid level and atrial fibrillation in patients with hyperthyroidism on medical data analysis context of IoT

BACKGROUND

Dysfunctions in metabolism and endocrine systems are outcomes of disruptions in human physiological processes, often leading to disease onset. External factors can hinder the human body's innate capacity for self-regulation and healing, particularly when immune responses are compromised, allowing these factors to interfere with normal bodily functions directly.

OBJECTIVE

To explore the effect of uric acid expression water in blood on the occurrence of atrial fibrillation in patients with hyperthyroidism, the expression level of uric acid in the blood and other physiological indexes were compared between patients with no symptoms of atrial fibrillation and patients with hyperthyroidism with symptoms of atrial fibrillation, to find the correlation between them.

METHODS

A group of 112 hyperthyroidism patients who were admitted to our hospital from September 2019 to March 2020 were chosen and split into two groups. The control group consisted of 56 individuals (21 men and 35 women) aged between 16 and 86 years old, with an average age of 46.23 years (± 7.63). The observation group consisted of 56 individuals (24 males and 32 females) between 15 and 79 years, with an average age of 53.44 years (± 8.91).

RESULTS

In the patients who were not treated with drugs before hospitalization the disease course and symptoms varied. The patients' clinical medical and demographic data were recorded and the patients' physiological indexes were obtained through blood tests and analysis. The differences between the two groups were analyzed by renal function, blood lipid index, thyroid function, and cardiac ultrasound, and these influencing factors were analyzed by regression analysis. The research adhered to ethical norms and ensured clear data presentation by using a rigorous technique to compare uric acid levels and physiological indicators among various patient groups.

CONCLUSION

The study concentrated on the validation, repeatability, and contextual interpretation of data to provide a robust and rigorously scientific comparison. The most common is the increase of uric acid in the blood, which can induce other diseases, and atrial fibrillation is one of the most common diseases of cardiovascular diseases.

Thyrotoxic Cardiomyopathy: State of the Art

Thyroid hormones, mainly triiodothyronine, have genomic and non-genomic effects on cardiomyocytes related to the contractile function of the heart. Thyrotoxicosis, which is the set of signs and symptoms derived from the excess of circulating thyroid hormones, leads to increased cardiac output and decreased systemic vascular resistance, increasing the volume of circulating blood and causing systolic hypertension. In addition, the shortening of the refractory period of cardiomyocytes produces sinus tachycardia and atrial fibrillation. This leads to heart failure. Approximately 1% of patients with thyrotoxicosis develop thyrotoxic cardiomyopathy, a rare but potentially fatal form of dilated cardiomyopathy. Thyrotoxic cardiomyopathy represents a diagnosis of exclusion, and prompt identification is crucial as it is a reversible cause of heart failure, and heart function can be recovered after achieving a euthyroid state using antithyroid drugs. Radioactive iodine therapy and surgery are not the best initial therapeutic approach. Moreover, it is important to manage cardiovascular symptoms, for which beta blockers are the first-line therapeutic option.