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Faisal M, Mumtaz Z, Mueed A, Ali S, Raza HH, Khan S, Salma S, Mujtaba M, Karim M, Qadir F. Routine Measurement of Thyroid Stimulating Hormone in Patients Presenting With Third-Degree Atrioventricular Block: Do We Really Need It? Cureus 2021; 13:e12712. [PMID: 33614317 PMCID: PMC7883583 DOI: 10.7759/cureus.12712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
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.
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Affiliation(s)
- Muhammad Faisal
- Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Zubair Mumtaz
- Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Abdul Mueed
- Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Sajid Ali
- Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Haseeb H Raza
- Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Samra Khan
- Medicine, Liaquat National Hospital, Karachi, PAK
| | - Sayeda Salma
- Cardiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Mustajab Mujtaba
- Cardiology, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Musa Karim
- Research, National Institute of Cardiovascular Diseases, Karachi, PAK
| | - Faisal Qadir
- Electrophysiology, National Institute of Cardiovascular Diseases, Karachi, PAK
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Gorenek B, Boriani G, Dan GA, Fauchier L, Fenelon G, Huang H, Kudaiberdieva G, Lip GYH, Mahajan R, Potpara T, Ramirez JD, Vos MA, Marin F, Blomstrom-Lundqvist C, Rinaldi A, Bongiorni MG, Sciaraffia E, Nielsen JC, Lewalter T, Zhang S, Gutiérrez O, Fuenmayor A. European Heart Rhythm Association (EHRA) position paper on arrhythmia management and device therapies in endocrine disorders, endorsed by Asia Pacific Heart Rhythm Society (APHRS) and Latin American Heart Rhythm Society (LAHRS). Europace 2018; 20:895-896. [DOI: 10.1093/europace/euy051] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 02/25/2018] [Indexed: 12/18/2022] Open
Affiliation(s)
| | - Giuseppe Boriani
- Cardiology Division, Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Policlinico di Modena, Modena, Italy
| | - Gheorge-Andrei Dan
- University of Medicine and Pharmacy “Carol Davila”, Colentina University Hospital, Bucharest, Romania
| | - Laurent Fauchier
- Centre Hospitalier Universitaire Trousseau et Université François Rabelais, Tours, France
| | | | - He Huang
- Renmin Hospital of Wuhan University, Wuhan, China
| | | | - Gregory Y H Lip
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK
- Aalborg Thrombosis Research Unit, Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
| | - Rajiv Mahajan
- The University of Adelaide, Lyell McEwin Hospital, Royal Adelaide Hospital and SAHMRI, Adelaide, Australia
| | - Tatjana Potpara
- School of Medicine, Belgrade University; Cardiology Clinic, Clinical Centre of Serbia, Belgrade, Serbia
| | | | | | | | | | | | | | | | | | | | - Shu Zhang
- Beijing Fuwai Hospital, Beijing, China
| | | | - Abdel Fuenmayor
- Electrophysiology and Arrhythmia Section, Cardiovascular Research Institute, University Hospital of The Andes, Avenida 16 de Septiembre, Mérida 5101, Venezuela
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Abstract
Thyroid hormones modulate every component of the cardiovascular system necessary for normal cardiovascular development and function. When cardiovascular disease is present, thyroid function tests are characteristically indicated to determine if overt thyroid disorders or even subclinical dysfunction exists. As hypothyroidism, hypertension, and cardiovascular disease all increase with advancing age, monitoring of thyroid-stimulating hormone, the most sensitive test for hypothyroidism, is important in this expanding segment of our population. A better understanding of the impact of thyroid hormonal status on cardiovascular physiology will enable health care providers to make decisions about thyroid hormone evaluation and therapy in concert with evaluating and treating hypertension and cardiovascular disease. The goal of this review is to access contemporary understanding of the effects of thyroid hormones on normal cardiovascular function and the potential role of overt and subclinical hypothyroidism and hyperthyroidism in a variety of cardiovascular diseases.
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Affiliation(s)
- Ira Martin Grais
- Department of Medicine/Cardiology Division, Northwestern Feinberg School Medicine, Chicago, Ill.
| | - James R Sowers
- Department of Internal Medicine, University of Missouri School of Medicine, Columbia, Mo; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Mo; Diabetes and Cardiovascular Center, University of Missouri School of Medicine, Columbia, Mo; Harry S. Truman Veterans Affair Medical Center, Columbia, Mo
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Ozcan KS, Osmonov D, Erdinler I, Altay S, Yildirim E, Turkkan C, Hasdemir H, Cakmak N, Alper AT, Satilmis S, Gurkan K. Atrioventricular block in patients with thyroid dysfunction: Prognosis after treatment with hormone supplementation or antithyroid medication. J Cardiol 2012; 60:327-32. [DOI: 10.1016/j.jjcc.2012.05.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 04/27/2012] [Accepted: 05/16/2012] [Indexed: 10/28/2022]
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Almeida NAS, Cordeiro A, Machado DS, Souza LL, Ortiga-Carvalho TM, Campos-de-Carvalho AC, Wondisford FE, Pazos-Moura CC. Connexin40 messenger ribonucleic acid is positively regulated by thyroid hormone (TH) acting in cardiac atria via the TH receptor. Endocrinology 2009; 150:546-54. [PMID: 18787025 DOI: 10.1210/en.2008-0451] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Thyroid hormone (TH) regulates many cardiac genes via nuclear thyroid receptors, and hyperthyroidism is frequently associated with atrial fibrillation. Electrical activity propagation in myocardium depends on the transfer of current at gap junctions, and connexins (Cxs) 40 and 43 are the predominant junction proteins. In mice, Cx40, the main Cx involved in atrial conduction, is restricted to the atria and fibers of the conduction system, which also express Cx43. We studied cardiac expression of Cx40 and Cx43 in conjunction with electrocardiogram studies in mice overexpressing the dominant negative mutant thyroid hormone receptor-beta Delta337T exclusively in cardiomyocytes [myosin heavy chain (MHC-mutant)]. These mice develop the cardiac hypothyroid phenotype in the presence of normal serum TH. Expression was also examined in wild-type mice rendered hypothyroid or hyperthyroid by pharmacological treatment. Atrial Cx40 mRNA and protein levels were decreased (85 and 55%, respectively; P < 0.001) in MHC-mt mice. Atrial and ventricular Cx43 mRNA levels were not significantly changed. Hypothyroid and hyperthyroid animals showed a 25% decrease and 40% increase, respectively, in Cx40 mRNA abundance. However, MHC-mt mice presented very low Cx40 mRNA expression regardless of whether they were made hypothyroid or hyperthyroid. Atrial depolarization velocity, as represented by P wave duration in electrocardiograms of unanesthetized mice, was extremely reduced in MHC-mt mice, and to a lesser extent also in hypothyroid mice (90 and 30% increase in P wave duration). In contrast, this measure was increased in hyperthyroid mice (19% decrease in P wave duration). Therefore, this study reveals for the first time that Cx40 mRNA is up-regulated by TH acting in cardiac atria via the TH receptor and that this may be one of the mechanisms contributing to atrial conduction alterations in thyroid dysfunctions.
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Affiliation(s)
- Norma A S Almeida
- Laboratório de Endocrinologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, Brazil
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Abstract
Amiodarone blocks the action of thyroid hormone by the inhibition of 5'-deiodinase which reduces production of T3 in peripheral tissues and possibly by blocking nuclear binding of T3. Since the drug inhibits peripheral conversion of T4 to T3, many patients taking amiodarone have abnormal thyroid function studies (increased T4 and rT3; decreased T3) despite being euthyroid. Treatment of patients with amiodarone generates an iodine excess, which contributes greatly to the significant incidence of altered thyroid status in this population. The diagnosis of hyperthyroidism and hypothyroidism can be difficult. However, using the overall clinical picture and the tolerance limits of hormone levels determined for patients remaining euthyroid on amiodarone therapy, the accurate diagnosis of clinically significant thyroid dysfunction can almost always be made. To screen for thyroid disease, thyroid function should be assessed before initiating therapy, semiannually during therapy or whenever clinical features of thyroid dysfunction occur. Subclinical hypothyroidism as denoted by modest increases in TSH levels do not require treatment or the discontinuation of amiodarone therapy. An appreciation of the mechanism of the interaction between amiodarone and thyroid hormone metabolism allows the clinician to recognize thyroid dysfunction at an early stage and initiate appropriate therapy, thereby minimizing the morbidity associated with forms of amiodarone toxicity.
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Affiliation(s)
- K Nademanee
- Medical and Research Service, West Los Angeles VA Medical Center, CA 90073
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