The Effects of Early Antithyroid Therapy for Endogenous Subclinical Hyperthyroidism in Clinical and Heart Abnormalities
Abstract
Subclinical hyperthyroidism has been associated with harmful cardiac effects, but its treatment remains controversial. This study was designed to assess the cardiac effects of the normalization of serum TSH concentration in patients with endogenous subclinical hyperthyroidism. Ten patients (median age, 59 yr; range, 16-72 yr) with normal serum free T(4) and free T(3) concentration and a stable suppression of serum TSH levels were evaluated by Doppler-echocardiography, by standard and 24-h electrocardiography monitoring (Holter), and by the clinical Wayne index. Ten subjects, matched for age and sex, were used as controls. Patients were reevaluated 6 months after achieving stabilized euthyroidism by using methimazole with a median initial dose of 20 mg daily (10-30 mg daily). After reaching euthyroidism, we found a significant decrease in the heart rate (P = 0.008), the total number of beats during 24 h (P = 0.004), and the number of atrial (P = 0.002) and ventricular (P = 0.003) premature beats. Echocardiographical data resulted in a reduction of the left ventricular mass index (P = 0.009), interventricular septum thickness (P = 0.008), and left ventricular posterior wall thickness (P = 0.004) at diastole. Furthermore, the early diastolic peak flow velocity deceleration rate was significantly higher (P = 0.02) in the untreated patients compared with controls. The Wayne clinical index was higher in patients than in controls (P = 0.001) and decreased after treatment (P = 0.004). Serum TSH concentration returned to normal values after 2.5 months (range, 1.0-7.0 months) on methimazole therapy (0.05 vs. 1.42 mU/liter; P = 0.002). Serum free T(4) values were normal in patients before treatment but significantly decreased after reaching the euthyroidism (16.9 vs. 11.5 pmol/liter; P = 0.002). In contrast, serum free T(3) concentration did not differ among the groups. In conclusion, our findings support that early antithyroid therapy should be considered in patients with endogenous subclinical hyperthyroidism, where it is needed to prevent potential progression to a more advanced heart disease.
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Some studies suggest that cardioselective β-blockers or treatment of SHyper with ATDs may improve symptoms, heart rate and supraventricular arrhythmias in patients with grade 2 SHyper.
“Some studies suggest that cardioselective β-blockers [47,48] or treatment of SHyper with ATDs [46,67] may improve symptoms, heart rate and supraventricular arrhythmias in patients with grade 2 SHyper.”
From The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism (2015) · cites this paper as [46]
Subclinical hyperthyroidism may be associated with symptoms and signs of mild thyroid hormone excess, including palpitations, tremor, heat intolerance, sweating, nervousness, anxiety, and reduced exercise tolerance.
“SHyper may be associated with symptoms and signs of mild thyroid hormone excess, i.e. palpitations, tremor, heat intolerance, sweating, nervousness, anxiety and reduced exercise tolerance [45,46] .”
From The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism (2015) · cites this paper as [46]
Sinus tachycardia and atrial premature beats are frequently observed in young subclinical hyperthyroidism patients with undetectable serum TSH.
“Sinus tachycardia and atrial premature beats are frequently observed in young SHyper patients with undetectable serum TSH [45,46] .”
From The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism (2015) · cites this paper as [46]
Impaired quality of life, in both mental and physical components, has been documented in young patients with subclinical hyperthyroidism and undetectable serum TSH.
“Impaired quality of life, in terms of both mental and physical components, has also been documented in young patients with SHyper and undetectable serum TSH [45,46] .”
From The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism (2015) · cites this paper as [46]
In young adults with undetectable serum TSH levels, subclinical hyperthyroidism may increase left ventricular mass, arterial stiffness, and left atrial size, and may induce diastolic dysfunction and impair left ventricular performance.
“In young adults with undetectable serum TSH levels, SHyper may increase left ventricular mass, arterial stiffness and left atrial size, and may induce diastolic dysfunction and impair left ventricular performance [45,46,67] .”
From The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism (2015) · cites this paper as [46]
Mechanistic correlates of these findings include increased left ventricular mass and impaired left ventricular function in SH that improve with treatment.
“Mechanistic correlates of these findings include increased left ventricular mass and impaired left ventricular function in SH that improve with treatment (393-396).”
From 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis (2016) · cites this paper as [393]
The evidence rests only with small uncontrolled studies that have shown improvements in cardiac structure and function, heart rate and the frequency of premature atrial and ventricular beats, bone mineral density, and muscle strength.
“Thus, the evidence rests only with small uncontrolled studies that have shown improvements in cardiac structure and function, heart rate and the frequency of premature atrial and ventricular beats, bone mineral density, and muscle strength (393)(394)(395)(396)405,(414)(415)(416)(417)426).”
From 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis (2016) · cites this paper as [393]
One uncontrolled study of middle-aged patients showed an improvement in hyperthyroid symptoms with therapy.
“One uncontrolled study of middle-aged patients showed an improvement in hyperthyroid symptoms with therapy (393).”
From 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis (2016) · cites this paper as [393]
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References 46 · Cited by 177
- Authors
- Sgarbi, J. A., Villaça, F. G., Garbeline, B., Villar, H. E., & Romaldini, J. H.
- Affiliations
- Faculdade de Medicina de Marília (BR)
- Pontifícia Universidade Católica de Campinas (BR)
- Corresponding author
- Romaldini, João H.
- Venue
- The Journal of Clinical Endocrinology & Metabolism
- Publisher
- The Endocrine Society
- Published
- 2003-04
- Volume
- 88
- Issue
- 4
- Pages
- 1672-1677
- ISSN
- 0021-972X (ISSN-L)
- 1945-7197
- OpenAlex
- W2119950851
- Cited by
- 177
- References
- 46
- Citations by year
- 2024: 6 · 2023: 2 · 2022: 6 · 2021: 2 · 2020: 7 · 2019: 10 · 2018: 8 · 2017: 4 · 2016: 6 · 2015: 7 · 2014: 8 · 2013: 16 · 2012: 17
- FWCI
- 6.32
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- The Journal of Clinical Endocrinology & Metabolism (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
- Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
- Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiovascular Function and Risk Factors
- Keywords
- subclinical hyperthyroidism, antithyroid drug therapy, methimazole, TSH suppression, cardiac effects, extrasystoles, left ventricular mass, diastolic function, heart rate, free thyroxine, free T3, euthyroidism, Doppler echocardiography, Holter monitoring, left ventricular hypertrophy, atrial fibrillation
- MeSH terms
- Adolescent, Adult, Aged, Arrhythmias, Cardiac, Diastole, Echocardiography, Electrocardiography, Female, Heart Diseases, Heart Rate, Heart Ventricles, Humans, Hyperthyroidism, Male, Methimazole, Middle Aged, Systole, Antithyroid Agents, Thyroid Gland, Thyrotropin, Thyroxine, Triiodothyronine
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