Atrioventricular block in patients with thyroid dysfunction: Prognosis after treatment with hormone supplementation or antithyroid medication

A systematic review of the clinical characteristics and course of atrioventricular blocks in hyperthyroidism

BACKGROUND

Atrioventricular block (AVB) is rare in hyperthyroidism (HTH). Little is known about the true prevalence, clinical course, optimal management, and outcomes of different types of AVBs in patients with HTH. To address these uncertainties, we aimed to conduct a systematic review by combining the available literature to provide more meaningful data regarding AVBs in HTH.

METHODS

We systematically searched PubMed, Scopus, Embase, and Google Scholar for articles reporting patients who developed AVB in the context of HTH. Data were analysed in STATA 16. The main outcomes included types of AVB, frequency of pacemaker insertion, and resolution of AVB. The systematic review is registered with the International Prospective Register of Systematic Reviews (PROSPERO) with the identification number CRD42022335598.

RESULTS

A total of 56 studies (39 case reports, 12 case series, 3 conference abstracts, 1 retrospective study, and 1 prospective observational study) with 87 patients were included in the analysis, with a mean age of 39.1 ± 17.6 years. Females constituted 65.7% (n = 48) of the cohort. Complete heart block (CHB) was the most commonly reported AVB (N = 45, 51.7%), followed by first-degree AVB (16.1%) and second-degree AVB (14.9%). Overall, 21 patients underwent pacing. A permanent pacemaker was inserted in one patient with second-degree AVB and six patients with CHB. Mortality was reported in one patient with CHB. The clinical course and management of HTH and AVBs did not differ in patients with CHB or lower-degree blocks. Apart from lower rates of goitre and more use of carbimazole in those who underwent pacing, no differences were found when compared to the patients managed without pacing.

CONCLUSION

Current data suggest that CHB is the most common type of AVB in patients with HTH. Most patients can be managed with anti-thyroid management alone. Additionally, whether pacemaker insertion alters the clinical outcomes needs further exploration.

Hyperthyroidism and severe bradycardia: Report of three cases and review of the literature

BACKGROUND

Hyperthyroidism often leads to tachycardia, but there are also sporadic reports of hyperthyroidism with severe bradycardia, such as sick sinus syndrome (SSS) and atrioventricular block. These disorders are a challenge for clinicians.

CASE SUMMARY

We describe three cases of hyperthyroidism with SSS and found 31 similar cases in a PubMed literature search. Through the analysis of these 34 cases, we found 21 cases of atrioventricular block and 13 cases of SSS, with 67.6% of the patients experiencing bradycardia symptoms. After drug treatment, temporary pacemaker implantation, or anti-hyperthyroidism treatment, the bradycardia of 27 patients (79.4%) was relieved, and the median recovery time was 5.5 (2-8) d. Only 7 cases (20.6%) needed permanent pacemaker implantation.

CONCLUSION

Patients with hyperthyroidism should be aware of the risk of severe bradycardia. In most cases, drug treatment or temporary pacemaker placement is recommended for initial treatment. If the bradycardia does not improve after 1 wk, a permanent pacemaker should be implanted.

Atrioventricular Block: An Unusual Presentation of Overactive Thyroid

The clinical features of hyperthyroidism are varied, but bradyarrhythmia and atrioventricular (AV) block are typically not reported in hyperthyroid patients. We present here a case of primary hyperthyroidism with symptomatic high-grade AV block as the sole presenting feature of hyperthyroidism without any obvious precipitating factors for thyroid disease or AV block. This case highlights a rare presentation of high-grade AV block with the risk of progression to complete AV block as a complication of an untreated overactive thyroid.

Overt hypothyroidism complicated by complete heart block and severe hyperlipidemia. A case report

Background

Hypothyroidism can cause a variety of manifestations, including cardiovascular disorders. The most frequent clinical signs are sinus bradycardia and pericardial effusion. The affected patient generally has significant symptoms. Hypothyroidism infrequently results in a complete atrioventricular block.

Case presentation

A 19-year-old girl presented to our cardiology clinic with generalized tiredness, edema in her lower limbs and face, constipation, and a menstruation abnormality in the previous six months. With a normal ejection fraction on echocardiography, an electrocardiogram revealed complete atrioventricular block. When she was admitted, her laboratory testing showed that she had severely raised Thyroid Stimulating Hormone (TSH) levels, severe dyslipidemia with normal electrolytes, and normal liver and kidney function tests. The patient was treated with 50mg Thyroxine to her. She had significant improvement within two weeks of treatment. Up on the next follow-up (at one-month), her electrocardiogram returned to normal sinus rhythm without any evidence of atrioventricular block and that the lipid profile had returned to normal.

Clinical discussion

In its first stages, hypothyroidism can not show any obvious symptoms. Untreated hypothyroidism over time can lead to a variety of health issues, including obesity, joint discomfort, infertility, and heart disease. This current case demonstrates how levothyroxine medication successfully managed a young female patient's severe hypothyroidism, difficult total heart block, severe hyperlipidemia, and long-standing menstrual irregularity.

Conclusion

We found that overt hypothyroidism caused a complete atrioventricular block and severe dyslipidemia, and that thyroxin therapy completely corrected both conditions.

An Adolescent Patient with Sick Sinus Syndrome Complicated by Hypothyroidism Carrying an SCN5A Variant

Previous studies have reported that hypothyroidism can lead to sick sinus syndrome (SSS) or other rhythm disturbances. Variants in the alpha subunit of the cardiac sodium channel (SCN5A) are known to be among the genetic causes of SSS. We encountered an adolescent patient with SSS and hypothyroidism who also harbored an SCN5A variant. The patient was a 13-year-old girl who was referred to our hospital because of bradycardia identified during a school electrocardiography screening. Clinical examination revealed severe hypothyroidism due to Hashimoto thyroiditis and SSS. After levothyroxine supplementation, her symptoms of hypothyroidism improved; however, the SSS did not. Genetic testing revealed a heterozygous variant (c.1066 G>A, p.Asp356Asn) in SCN5A. This is the first report of the coexistence of SSS due to an SCN5A variant and severe hypothyroidism in an adolescent patient. While patients with SCN5A variants exhibit phenotypic heterogeneity due to the presence of various modifiers, the presence of severe hypothyroidism may affect the development of SSS. This case highlights the importance of genetic analysis, including testing for SCN5A variants, in patients with hypothyroidism complicated by SSS or cardiac conduction disorders.

Coexisting Thyroiditis and Carditis in a Patient with Lyme disease: Looking for a Unifying Diagnosis

Background/Objective

Lyme disease, the most common vector-borne infection in the United States, causes multisystem inflammation. We describe a patient who presented with symptoms of Lyme disease, carditis, and thyroiditis.

Case Report

A 53-year-old woman developed fatigue and dyspnea on exertion 1 month after returning from a trip to Delaware. Her electrocardiogram (ECG) showed first-degree atrioventricular (AV) block with a P-R interval up to 392 milliseconds, in the setting of elevated free thyroxine and undetectable thyroid-stimulating hormone levels. Lyme serology was positive. She was hospitalized and started on ceftriaxone. During the second day of hospitalization, AV block worsened to second-degree Mobitz type II but converted back to first-degree AV block after a few hours. Her 24-hour I-123 thyroid uptake and scan revealed markedly diminished I-123 uptake of 1.2%. On day 4, the P-R interval improved, and she was discharged on doxycycline for 3 weeks. P-R interval on ECG and repeated thyroid function tests were normal after finishing antibiotic treatment.

Discussion

In our patient, known exposure to the vector, a classic rash on the chest, improvement in the symptoms, and normalization of thyroid function tests after antibiotic therapy support Lyme infection as a cause of carditis and painless, autoimmune thyroiditis.

Conclusion

Our case highlights the importance of considering Lyme disease as a cause of painless, autoimmune thyroiditis, especially in patients with concurrent cardiovascular involvement.

Hypothyroidism and Complicated Sick Sinus Syndrome and Acute Severe Psychiatric Disorder: A Case Report

Background

Thyroxine is closely related to cardiovascular diseases, such as coronary heart disease, ventricular arrhythmia, atrioventricular block, myocardial systolic weakness, pericardial effusion, low cardiac output and hypertension. Previous studies have also found that hypothyroidism can also lead to mental disorders. Here, we present a rare case of severe hypothyroidism patient accompanied by sick sinus syndrome (SSS) as a cardiovascular manifestation needing cardiac pacing and severe mental disorders.

Case Presentation

A 42-year-old female patient, previously healthy, was referred to our hospital because of bradycardia complicated with sick sinus syndrome which requiring cardiac pacing and severe mental disorders. Her clinical features along with laboratory findings strongly suggested that the patient had severe hypothyroidism with sick sinus syndrome and mental disorders, both of which were reversible and successfully treated with levothyroxine.

Conclusion

This is the first reported case of hypothyroidism with sick sinus syndrome requiring pacemakers and psychiatric disorders, and the symptoms can be improved and reversed after thyroxine supplementation. This case highlights the importance of hypothyroidism screening when faced with unexplained psychosis or sick sinus syndrome, especially if combined.

Routine Measurement of Thyroid Stimulating Hormone in Patients Presenting With Third-Degree Atrioventricular Block: Do We Really Need It?

Background Hypothyroidism can be a cause of sinus bradycardia. However, thyroid laboratory evaluation is often performed routinely in patients with complete heart block (CHB) though there is little data to support this practice. This study aimed to assess the frequency of thyroid dysfunction in patients presenting with CHB without clinical features of hypothyroidism. Methodology All patients referred for permanent pacemaker implantation for CHB were included in this cross-sectional study. Patients with known thyroid disorder or clinical features of thyroid disorder were excluded. Demographic, electrocardiography (EKG), and routine thyroid stimulating hormone (TSH) screening results were recorded. Results A total of 102 patients with complete atrioventricular (AV) block were enrolled in the study of which 50.0% (51) were male. The mean age was 61.09 ± 11.74. Co-morbidities included diabetes mellitus 44.1% (45), smoking 36.3% (37), and hypertension 55.9% (57). Mean EKG atrial rate was 82.97 ± 31.31 mmHg with a mean ventricular escape rate of 36.17 ± 5.93. Permanent pacemakers were implanted in all of the patients. Only one patient had an abnormal TSH. Conclusions We found a very low prevalence of thyroid dysfunction among patients without clinical features of thyroid dysfunction presenting with third-degree AV block. This calls for cautious prescription of thyroid testing in clinically euthyroid patients.

New-onset arrhythmia associated with patients hospitalized for thyroid dysfunction

BACKGROUND

Thyroid dysfunction has been associated with cardiovascular dysfunction in the literature. However, the frequency of new-onset arrhythmias associated with thyroid disease hospitalization is unknown. Hence, we analyzed frequency, in-hospital outcomes, and resource utilization of new-onset arrhythmias associated with thyroid dysfunction hospitalizations.

METHODS

The patients who were admitted with the primary reason of thyroid dysfunction were included using appropriate international classification of disease, ninth revision, clinical modification (ICD-9-CM) codes. We then identified new-onset arrhythmias using appropriate ICD-9-CM codes. We utilized the "present on admission" variable to exclude arrhythmias that were present on admission.

RESULTS

Among the eligible patients with thyroid dysfunction, only 3% (n=12,111) developed a new-onset arrhythmia. Atrioventricular block (1.49%) is the most frequent followed by atrial fibrillation (0.92%), ventricular tachycardia (0.47%), atrial flutter (0.23%), supraventricular tachycardia (0.1%) and ventricular fibrillation (0.07%). Patients with new-onset arrhythmias were older (mean age 76.7±12.5 years), more predominantly white (n=9008, 74.4%), higher females (n= 7632, 63%), and had a higher frequency of comorbidities. In-hospital mortality occurred in 827 (6.8%) patients with new-onset arrhythmias and 8632 (2.2%) patients without new-onset arrhythmias (P-value <0.001). The medical length of stay and cost of hospitalization was also higher in these patients.

CONCLUSION

Thyroid dysfunction is not associated with significantly higher rates of new-onset arrhythmias while inpatient. However, when developed, these arrhythmias are associated with higher mortality and resource utilization. The patients admitted to the hospital should have thyroid function checked when found to have an arrhythmia.

Myxedema coma accompanied by sick sinus syndrome and hypoventilation: A case report

Myxedema coma is an emergency presentation of hypothyroidism, and cardiopulmonary manifestations of the disease are related to a high mortality rate. We herein report a case of myxedema coma accompanied by sick sinus syndrome requiring temporary cardiac pacing and hypercapnic respiratory failure in an 87-year-old woman. This case is unique because both of the cardiac and pulmonary manifestations were reversible and successfully treated with thyroid hormone replacement. Our case indicates that early detection of the condition and administration of levothyroxine are essential to improve the life-threatening condition and avoid invasive treatment such as permanent pacemaker implantation or intubation.

Tips for management of arrhythmias in endocrine disorders from an European Heart Rhythm Association position paper

In endocrine diseases, hormonal changes, electrolyte abnormalities, and the deterioration of heart structure can lead to various arrhythmias. In diabetic patients, hypoglycemia, hyperglycemia, and hypokalemia can trigger arrhythmias, and diabetic cardiomyopathy can also cause electrical and structural remodeling to form substrates for arrhythmias. The risk of atrial fibrillation (AF) increases in hyperthyroidism; however, the prevalence of ventricular arrhythmias in hypothyroidism is higher. Besides AF and ventricular tachycardias, bradycardias and atrioventricular blocks can also be seen in pheochromocytoma due to the desensitization of adrenergic cardiovascular receptors. The correction of metabolic and electrolyte disturbances in patients with adrenal cortex disease should be the main approach in the prevention and treatment of arrhythmias. Early initiation of treatment in patients with acromegaly seems to decrease the development of cardiac remodeling and ventricular arrhythmia. Early and late after depolarizations due to hypercalcemia in hyperparathyroidism can lead to life-threatening ventricular arrhythmias. This elegant position paper provides important recommendations regarding prevention and treatment of arrhythmias for specific endocrine disorders.

A Pacemaker that was Avoided

Thyroxine is an essential hormone in the human body and exerts many effects on the cardiovascular system. The low metabolic state in hypothyroidism causes bradycardia and reduced cardiac contractility leading to reduced cardiac output. Severe bradycardia and atrioventricular (AV) blocks secondary to hypothyroidism have also been reported. We present a case of severe hypothyroidism causing a high-grade AV block which was successfully treated with thyroxine hormone replacement without requiring cardiac pacemaker placement.

Second degree AV block and severely impaired contractility in cardiac myxedema: a case report

The heart is a major target organ for thyroid hormone action. Severe overt hypothyroidism can result in diastolic hypertension, lowered cardiac output, impaired left ventricular contractility and diastolic relaxation, pericardial effusion and bradycardia. However, the function of the atrial pacemaker is usually normal and the degree by which the heart rate slows down is often modest. Here we report the case of a 20 year old male Caucasian with severe overt hypothyroidism. He presented with syncopation due to second degree atrioventricular block type Mobitz 2 and heart failure with reduced ejection fraction (38 %). Laboratory testing revealed a severe overt hypothyroidism with markedly elevated TSH (>100 mIU/L) and reduced fT3 and fT4 levels. The condition was caused by hypothyroid Graves’ disease (Graves’ disease with Hashimoto component). Although magnetic resonance imaging of the heart demonstrated decreased cardiac contractility and pericardial effusion, suggesting peri-myocarditis, plasma levels for BNP and troponin I were low. A possible infectious cause was unlikely, since testing for cardiotropic viruses was negative. The patient was treated with intravenous levothyroxine and after peripheral euthyroidism had been achieved, left ventricular ejection fraction returned to normal and pericardial effusion dissolved. Additionally, bradycardiac episodes abated, although intermittent second degree AV block was still occasionally present during the night. In conclusion, overt hypothyroidism may be associated by cardiac myxedema affecting both electrophysiology and contractility, observations that underscore the necessity of thyroid testing in different phenotypes of heart failure.

Second-degree atrioventricular block type II and third-degree atrioventricular block requiring cardiac pacing after tooth extraction

Because atrioventricular block can cause cardiovascular collapse, the rapid management of this condition is necessary. An 82-year-old man complained of discomfort after tooth extraction, and electrocardiography showed second- and third-degree atrioventricular blocks. Dentists should monitor patients who report discomfort using electrocardiography because of the possibility of life-threatening arrhythmia.

Cardiac device-related endocarditis: 31-Years' experience

BACKGROUND

Cardiac device-related endocarditis (CDE) is a major complication of the implantation of a pacemaker and defibrillator. The experience in a single high-volume tertiary center is reported.

METHODS

Thirty one years (1980-2011) of cases of CDE were analyzed retrospectively and compared to overall insertion data; the clinical course and management strategies of these patients have been reviewed.

RESULTS

A total of 23 cases (16 male, median age 72 years) were identified, 20 of these cases were determined at our institution where 5287 procedures were performed (endocarditis rate 0.38%). Thirteen patients were determined to have a cardiac device pocket infection. Infection in 7 cases (30%) was caused by lead(s). However, in 16 cases (70%) both leads and the pocket of devices were the reason of infection. Median time was 13.5 months for presentation. Patients who had undergone the last procedure within 6 months were admitted earlier than those with longer post procedure time (p<0.05). Transesophageal echocardiography demonstrated lead vegetations in 13 of the 16 cases (81%). Organisms were identified in 18 cases (78%)-78% Staphylococci (56% Staphylococcus aureus). Leads of the device were removed in 17 cases (74%); seven cases by percutaneous simple traction and 10 cases by sternotomy. Six major complications attributable to device-related endocarditis were observed: four deaths (mortality 17.4%); one splenic abscess requiring splenectomy; and one septic pulmonary embolism; median follow-up 49 months.

CONCLUSION

A CDE endocarditis rate of 0.38% was demonstrated. It remains a rare but potentially lethal complication of device implantation.