Left ventricular myocardial impairment in subclinical hypothyroidism assessed by a new ultrasound tool: pulsed tissue Doppler

The association between TSH and thyroid hormones in the normal or subclinical dysfunction range with left ventricular diastolic dysfunction

Thyroid hormones modulate the cardiovascular system. However, the effects of subclinical thyroid dysfunction and euthyroidism on cardiac function remain unclear. We investigated the association between left ventricular (LV) diastolic dysfunction and subclinical thyroid dysfunction or thyroid hormones within the reference range. This cross-sectional study included 26,289 participants (22,197 euthyroid, 3,671 with subclinical hypothyroidism, and 421 with subclinical thyrotoxicosis) who underwent regular health check-ups in the Republic of Korea. Individuals with thyroid stimulating hormone (TSH) levels > 4.2 µIU/mL and normal free thyroxine (FT4, 0.78-1.85 ng/dL) and triiodothyronine (T3, 76-190 ng/dL) levels were defined as having subclinical hypothyroidism. Individuals with serum TSH levels < 0.4 µIU/mL and normal FT4 and T3 levels were defined as having subclinical thyrotoxicosis. The cardiac structure and function were evaluated using echocardiography. LV diastolic dysfunction with normal ejection fraction (EF) was defined as follows: EF of > 50% and (a) E/e' ratio > 15, or (b) E/e' ratio of 8-15 and left atrial volume index ≥ 34 mL/m2. Subclinical hypothyroidism was significantly associated with cardiac indices regarding LV diastolic dysfunction. The odds of having LV diastolic dysfunction was also increased in participants with subclinical hypothyroidism (adjusted odds ratio [AOR] 1.36, 95% confidence interval [CI], 1.01-1.89) compared to euthyroid participants. Subclinical thyrotoxicosis was not associated with LV diastolic dysfunction. Among the thyroid hormones, only serum T3 was significantly and inversely associated with LV diastolic dysfunction even within the normal range. Subclinical hypothyroidism was significantly associated with LV diastolic dysfunction, whereas subclinical thyrotoxicosis was not. Serum T3 is a relatively important contributor to LV diastolic dysfunction compared to TSH or FT4.

Subclinical central hypothyroidism in patients with hypothalamic-pituitary disease: does it exist?

Central hypothyroidism (CH) is characterized by decreased thyroid hormone production due to insufficient stimulation of an otherwise normal thyroid gland by TSH. In patients with established hypothalamic-pituitary disease, a low FT4 concentration is considered highly specific, although poorly sensitive, for the diagnosis of CH. That would be comparable to diagnosing primary hypothyroidism in patients at risk only when serum FT4 concentrations are below the reference range, missing all patients with subclinical primary hypothyroidism and preventing proper therapy in patients in which thyroxine replacement is clearly beneficial. Cardiac time intervals, especially the isovolumic contraction time (ICT), have been considered the gold standard of peripheral thyroid hormone action. Using Doppler echocardiography, we have previously shown a very high proportion of prolonged ICT in patients with hypothalamic-pituitary disease and serum FT4 levels indistinguishable from controls. As ICT decreased/normalized after thyroxine-induced increases in FT4 concentrations within the normal reference range, prolonged ICT was considered a bona fide diagnostic biomarker of subclinical CH. Those findings challenge the usual interpretation that FT4 concentrations in the mid-reference range exclude hypothyroidism in patients with hypothalamic-pituitary disease. Rather, subclinical central hypothyroidism, a state analogous to subclinical primary hypothyroidism, seems to be frequent in patients with hypothalamic-pituitary disease and normal FT4 levels. They also challenge the notion that thyroid function is usually the least or the last affected in acquired hypopituitarism. The relevance of Doppler echocardiography to correctly diagnose and monitor replacement therapy in both clinical and subclinical forms of CH should improve quality of life and decrease cardiovascular risk, as already demonstrated in patients with clinical and subclinical primary hypothyroidism.

Subclinical Hypothyroidism, Kidney, and Heart from Normal to Uremic Milieu

Thyroid hormone (TH) imbalances, particularly subclinical hypothyroidism (SCHT), are associated with chronic kidney disease (CKD) and end-stage kidney disease (ESKD). SCHT is more prevalent in CKD and ESKD patients than in the general population, and this condition increases the risk of cardiovascular disease (CVD) morbidity and mortality. The risk of CVD is higher in CKD and ESKD patients compared with the general population. Traditional and nontraditional risk factors, including TH abnormalities, contribute to the high CVD burden in CKD and ESKD patients. The review discusses the link between CKD and hypothyroidism, with a focus on SCHT, and the mechanisms that lead to CVD burden.

Atrioventricular Longitudinal Mechanics Using Novel Speckle-Tracking Improved Risk Stratification Beyond Baseline Thyroid Hormone in Asymptomatic Subclinical Hypothyroidism

BACKGROUND

Hypothyroidism is reportedly associated with increased cardiovascular risk and heart failure. We aimed to elucidate the mechanistic influence of atrio-ventricular deformations and their prognostic utilizations in asymptomatic subclinical hypothyroidism (SCH).

METHODS

We assessed speckle-tracking of deformations among 4173 population-based asymptomatic individuals classified as euthyroid (0.25< thyroid-stimulating hormone [TSH] ≤4.0 μIU/mL, n=3799) or having mild (4< TSH ≤10.0 μIU/mL, n=349) or marked (TSH >10 μIU/mL, n=25) SCH. We further related deformational indices to outcomes of atrial fibrillation and heart failure.

RESULTS

Despite borderline differences in indexed left ventricular mass and left atrial volume (P=0.054 and 0.051), those classified as mild and marked SCH presented with modest but significant reductions of global longitudinal strain, and showed elevated E/tissue Doppler imaging (TDI)-e', markedly diminished peak atrial longitudinal strain and higher left atrial stiffness (all P<0.05) when compared with euthyroid subjects. A higher TSH level was independently associated with reduced TDI-s'/TDI-e', worse global atrio-ventricular strains (global longitudinal strain/peak atrial longitudinal strain), elevated E/TDI-e', and worsened left atrial strain rate components (all P<0.05). Over a median 5.6 years (interquartile range, 4.7-6.5 years) follow-up, myocardial deformations yielded independent risk prediction using Cox regression in models adjusted for baseline covariates, N-terminal pro-brain natriuretic peptide, E/e', and treatment effect. Incorporation of global atrio-ventricular strain (global longitudinal strain/peak atrial longitudinal strain) and strain rates further showed improved risk reclassification when added to the baseline TSH strata (classified as euthyroid and mild and marked SCH; all P<0.05). Cox regression models remained significant with improved risk reclassification beyond TSH-based strata by using slightly different deformational cutoffs after excluding marked SCH group.

CONCLUSIONS

Hypothyroidism, even when asymptomatic, may widely influence subclinical atrio-ventricular mechanical functions that may lead to higher heart failure and atrial fibrillation risk. We proposed the potential usefulness and prognostic utilization of myocardial strains in such population.

The association of presystolic wave with subclinical left-ventricular dysfunction in patients with subclinical hypothyroidism

PURPOSE

Subclinical hypothyroidism (SCH) patients develop left-ventricular dysfunction (LVD) in an earlier stage. LVD could be detected with myocardial performance index (MPI), left -ventricular global longitudinal strain (LVGLS), and conventional and tissue-Doppler imaging (TDI). A presystolic wave (PSW) detected on late diastole is associated with LVD. We aimed to determine whether there is an association between PSW and subclinical LVD assessed by different echocardiographic methods in SCH patients.

METHODS

We prospectively enrolled 105 patients diagnosed with SCH in this study. Patients were divided into two groups based on the presence of PSW. Both groups were compared with respect to demographic, clinical, and echocardiographic properties. Multivariable regression analysis was performed to detect predictors of subclinical LVD.

RESULTS

The study included 70 PSW-positive patients (66%, mean age: 50.2) and 35 PSW-negative patients (34%, mean age: 46.5). PSW-positive patients had a lower platelet and a higher RDW level compared to PSW-negative patients. PSW-positive patients had more frequent subclinical LVD, which was assessed by MPI, by conventional and TDI parameters, and by LVGLS. PSW velocity was significantly correlated with MPI velocity (r = 0.31, p = 0.009), TSH level (r = 0.44, p < 0.001), and with LVGLS (r = 0.33, p = 0.005). The presence of PSW was an independent predictor of subclinical LVD in multivariable logistic regression analysis detected with MPI, LVGLS, and TDI parameters (OR = 5.409, p = 0.03; OR = 4.872, p = 0.005; OR = 5.632, p = 0.014, respectively).

CONCLUSION

PSW prevalence was 66% in SCH patients. PSW velocity was significantly correlated with MPI and LVGLS. The presence of PSW was independently associated with subclinical LVD in SCH patients.

Evaluation of left atrial and ventricular myocardial functions by three-dimensional speckle tracking echocardiography in patients with euthyroid Hashimoto's thyroiditis

Hashimoto's Thyroiditis (HsT) is one of the most frequently occurring autoimmune diseases, characterized by lymphocytic infiltration, destruction and fibrosis of thyroid tissue and the presence of antibodies to thyroid peroxidase and thyroglobulin. The effects of euthyroid Hashimoto's thyroiditis (eHsT) on cardiovascular system are unclear. We aimed to identify if any deteriorations in LA and LV myocardial functions in patients with eHsT by 3D-STE in the current study. Fifty eight patients with eHsT and 60 age- and gender-matched controls were enrolled into the study. All participants underwent laboratory analyses which included thyroid hormones and thyroid autoantibody levels; and conventional 2D echocardiographic and 3D-STE analyses were performed. The mean age of the study patients was 34.5 ± 9 years, and 68.6% were female. Left ventricular global longitudinal strain (LV-GLS) was significantly depressed in the eHsT (+) group than in the control group (- 15.3 ± 3.6 vs. - 22.8 ± 3.8, p < 0.001). The LV-GLS was found to be disrupted linearly as thyroid autoantibodies increased (r = 0.684 for anti-TPO-ab and LV-GLS; r = 0.649 for anti-Tg-ab and LV-GLS). The present study demonstrated that 3D-STE is useful in the early detection of LV myocardial dysfunction in patients with eHsT. We found that eHsT had a negative effect on LV myocardial dynamics. According to these findings, these myocardial alterations that are present early in the disease process may be considered as a reason to start medical treatment earlier, even at the euthyroid stage to prevent LV myocardial impairment.

Cardiovascular Implications of Diabetes, Metabolic Syndrome, Thyroid Disease, and Cardio-Oncology in Women

Cardiovascular disease may be associated with several comorbidities, including diabetes mellitus, thyroid disorders, and the metabolic syndrome, which are predominantly observed in women and often starting at particular ages. In addition, common treatment options for carcinomas frequently seen in women may induce serious cardiotoxic effects. We review the scope of the problem, the pathophysiologic mechanisms involved, as well as the resulting abnormalities regarding cardiac structure and function as observed by using imaging techniques.

The effect of levothyroxine treatment on left ventricular function in subclinical hypothyroidism

OBJECTIVE

Treatment of subclinical hypothyroidism (ScH), especially the mild form of ScH, is controversial because thyroid hormones influence cardiac function. We investigate left ventricular systolic and diastolic function in ScH and evaluate the effect of 5-month levothyroxine treatment.

SUBJECTS AND METHODS

Fifty-four patients with newly diagnosed mild ScH (4.2 <TSH < 10.0 mU/L) and 30 euthyroid subjects matched by age were analysed. Laboratory analyses and an echocardiography study were done at the first visit and after 5 months in euthyroid stage in patients with ScH.

RESULTS

Compared to healthy controls, patients with ScH had a lower E/A ratio (1.03 ± 0.29 vs. 1.26 ± 0.36, p < 0.01), higher E/e' sep. ratio (762 ± 2.29 vs. 6.04 ± 1.64, p < 0.01), higher myocardial performance index (MPI) (0.47 ± 0.08 vs. 0.43 ± 0.07, p < 0.05), lower global longitudinal strain (GLS) (-19.5 ± 2.3 vs. -20.9 ± 1.7%, p < 0.05), and lower S wave derived by tissue Doppler imaging (0.077 ± 0.013 vs. 0.092 ± 0.011 m/s, p < 0.01). Levothyroxine treatment in patients with ScH contributed to higher EF (62.9 ± 3.9 vs. 61.6 ± 4.4%, p < 0.05), lower E/e' sep. ratio (6.60 ± 2.06 vs. 762 ± 2.29, p < 0.01), lower MPI (0.43 ± 0.07 vs. 0.47 ± 0.08%, p < 0.01), and improved GLS (-20.07 ± 2.7 vs. -19.55 ± 2.3%, p < 0.05) compared to values in ScH patients at baseline. Furthermore, in all study populations (ScH patients before and after levothyroxine therapy and controls), TSH levels significantly negatively correlated with EF (r = -0.15, p < 0.05), E/A (r = -0.14, p < 0.05), GLS (r = -0.26, p < 0.001), and S/TDI (r = -0.22, p < 0.01) and positively correlated with E/e' sep. (r = 0.14, p < 0.05).

CONCLUSION

Patients with subclinical hypothyroidism versus healthy individuals had subtle changes in certain parameters that indicate involvement of systolic and diastolic function of the left ventricle. Although the values of the parameters were in normal range, they were significantly different compared to ScH and the control group at baseline, as well as to the ScH groups before and after treatment.The results of our study suggest that patients with ScH must be followed up during treatment to assess improvement of the disease. Some of the echocardiography obtained parameters were reversible after levothyroxine therapy.

Subclinical hypothyroidism and the development of heart failure: an overview of risk and effects on cardiac function

The prevalence of subclinical hypothyroidism (SCH) ranges from 5 to 15% of the general population. However, it remains controversial if SCH warrants life-long thyroxine replacement therapy. Patients with a thyroid-stimulating hormone (TSH) level > 10 mIU/L have a higher risk of developing heart failure with reduced ejection fraction as compared to subjects with normal thyroid function. However, abnormally high TSH levels could also be connected with an overall lower metabolic rate and better survival in elderly subjects. The potential mechanisms responsible for diastolic dysfunction of the left ventricle (LV) in SCH are connected with endothelial dysfunction and arterial stiffness, inflammatory state and are driven by TSH apoptosis-derived microparticles. The impact of SCH on LV systolic function is more controversial, and it is connected not only with cardiac remodelling but also with predisposition of patients with SCH to the conditions leading to heart failure. This review presents an overview of processes in the context of potential benefits of thyroxine supplementation therapy.

TSH inhibits SERCA2a and the PKA/PLN pathway in rat cardiomyocytes

Elevated thyroid-stimulating hormone (TSH) levels often accompany impaired LV diastolic function and subtle systolic dysfunction in subclinical hypothyroidism (sHT). These cardiac dysfunctions are characterized by increases in mean aortic acceleration and pre-ejection/ejection time ratios. To explore the mechanism underlying these pathologies, we investigated the effects of TSH on sarcoplasmic reticulum calcium ATPase (SERCA2a) activity and expression in neonatal rat cardiomyocytes. TSH inhibited SERCA2a activity and expression by binding to TSH receptors in cardiomyocyte membranes and inhibiting the protein kinase A/phoshpolamban (PKA/PLN) signaling pathway. These results suggest that increases in serum TSH levels contribute to the development of cardiac diastolic and systolic dysfunction.

Cardiac ischemia/reperfusion injury is inversely affected by thyroid hormones excess or deficiency in male Wistar rats

AIM

Thyroid dysfunctions can increase the risk of myocardial ischemia and infarction. However, the repercussions on cardiac ischemia/reperfusion (IR) injury remain unclear so far. We report here the effects of hypothyroidism and thyrotoxicosis in the susceptibility to IR injury in isolated rat hearts compared to euthyroid condition and the potential role of antioxidant enzymes.

METHODS

Hypothyroidism and thyrotoxicosis were induced by administration of methimazole (MMZ, 300 mg/L) and thyroxine (T4, 12 mg/L), respectively in drinking water for 35 days. Isolated hearts were submitted to IR and evaluated for mechanical dysfunctions and infarct size. Superoxide dismutase types 1 and 2 (SOD1 and SOD2), glutathione peroxidase types 1 and 3 (GPX 1 and GPX3) and catalase mRNA levels were assessed by quantitative RT-PCR to investigate the potential role of antioxidant enzymes.

RESULTS

Thyrotoxicosis elicited cardiac hypertrophy and increased baseline mechanical performance, including increased left ventricle (LV) systolic pressure, LV developed pressure and derivatives of pressure (dP/dt), whereas in hypothyroid hearts exhibited decreased dP/dt. Post-ischemic recovery of LV end-diastolic pressure (LVEDP), LVDP and dP/dt was impaired in thyrotoxic rat hearts, whereas hypothyroid hearts exhibited improved LVEDP and decreased infarct size. Catalase expression was decreased by thyrotoxicosis.

CONCLUSION

Thyrotoxicosis was correlated, at least in part, to cardiac remodeling and increased susceptibility to IR injury possibly due to down-regulation of antioxidant enzymes, whereas hypothyroid hearts were less vulnerable to IR injury.

Echocardiographic evaluation of left ventricular diastolic dysfunction in subclinical hypothyroidism: A case-control study

PURPOSE

To study the prevalence of left ventricular diastolic dysfunction (LVDD) in patients with subclinical hypothyroidism (SCH) and the response of LVDD to L-thyroxine therapy.

MATERIALS AND METHODS

This cross-sectional case-control study with one longitudinal arm included 67 patients with SCH attending a tertiary care hospital in Uttarakhand, India, and 67 age- and sex-matched healthy controls. LVDD was assessed by 2D, pulsed-wave Doppler (PWD), continuous wave Doppler (CWD), and tissue Doppler echocardiography (TDE). Patients with LVDD received L-thyroxine therapy with reassessment for LVDD 6 months later.

RESULTS

SCH patients had a higher prevalence of LVDD than controls (13.43% versus 1.49%; p = 0.017). LVDD showed a significant association with gender (p = 0.004) and serum FT4 (p = 0.001). E velocity, E' velocity, A' velocity, iso-volumetric relaxation time (IVRT), E/A, and E'/A' ratios were significantly lower, while A velocity, deceleration time (DT), E/E' ratio, left atrial (LA) volume index, and peak tricuspid regurgitation (TR) velocity were significantly higher in cases than controls (p < 0.05 each). The E/A ratio correlated significantly with age, serum very low-density lipoprotein (VLDL), triglycerides (TG), thyroid stimulating hormone (TSH), free triiodothyronine (FT3), and high-density lipoprotein (HDL) (p < 0.05 each). E' velocity correlated significantly with age, serum total cholesterol, VLDL, and TG (p < 0.05 each), DT with serum total cholesterol (p = 0.047), and LA volume index with age (p = 0.021). Age (p = 0.016) and serum HDL (p = 0.029) were independent predictors of E/A ratio. Gender was an independent predictor for LVDD (p = 0.003). Echocardiographic indices for LVDD showed significant improvement after 6 months of L-thyroxine therapy (p < 0.05 each).

CONCLUSIONS

LVDD occurs commonly in SCH patients. It can be detected timely using echocardiography and may be reversed by L-thyroxine therapy.

Recombinant Human Thyrotropin Improves Endothelial Coronary Flow Reserve in Thyroidectomized Patients with Differentiated Thyroid Cancer

BACKGROUND

The role of thyrotropin (TSH) on the cardiovascular system has been poorly investigated. It is unknown whether the changes in the vasculature associated with thyroid diseases result from altered thyroid hormone action or whether they are a consequence of a direct effect of TSH on endothelial cells. The present study was designed to evaluate the endothelial response of coronary flow to TSH in patients with differentiated thyroid cancer (DTC) without cardiovascular risk factors.

METHODS

The study population consisted of three men and seven women (M_age = 32.6 ± 8 years) who underwent total thyroidectomy for DTC. All were receiving therapy with L-thyroxine to maintain TSH within the reference range. No patient was obese, or had hypertension, diabetes, or dyslipidemia. Patients underwent standard echo-Doppler examination with evaluation of the coronary flow reserve (CFR) of the distal left anterior descending artery obtained by cold pressure test (CPT) before and 24 h after the second recombinant human TSH (rhTSH) injection.

RESULTS

Left ventricular morphology and systolic and diastolic function were normal in all patients. Levels of thyroid hormones and thyroglobulin and antithyroglobulin antibodies did not differ significantly pre- versus post-rhTSH treatment, whereas TSH levels were higher after rhTSH administration. Blood pressure and heart rate were not affected by rhTSH. Coronary flow peak velocity at rest (22.3 ± 6 vs 23.2 ± 8.7; p = 0.66) did not differ between baseline and 24 h after rhTSH, while post-CPT velocity (29.3 ± 6.8 vs 34.4 ± 10.9; p < 0.05) and the CFR were higher after rhTSH administration (1.32 ± 0.2 vs. 1.53 ± 0.2; p < 0.01).

CONCLUSIONS

rhTSH administration may improve the CFR after the non-pharmacological stressor CPT in DTC patients. The increase of coronary blood flow after rhTSH suggests that TSH may exert a protective effect on the coronary endothelium.

The relationship between circulating TRAIL and endothelial dysfunction in subclinical hypothyroidism

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is associated with atherosclerosis. Subclinical hypothyroidism (sHT) is associated with the increased prevalence of atherosclerotic lesions and cardiovascular events. Therefore, we hypothesized that circulating TRAIL levels are associated with endothelial dysfunction in sHT patients. Two hundred and four patients with newly diagnosed sHT and 52 healthy subjects were recruited. Circulating TRAIL concentration was measured by an ELISA, and flow-mediated dilation (FMD) of brachial artery was measured using high-resolution ultrasound. The mean value of circulating TRAIL in newly diagnosed sHT patients was 67.2 pg/ml, which was lower than that in controls (78.5 pg/ml, p < 0.001). By dividing the distribution of FMD levels into quartiles, TRAIL levels were increased gradually with the increase of FMD levels (p < 0.001). Multivariate regression analysis demonstrated that serum TRAIL levels were independently associated with FMD (p = 0.007). By logistic regression analysis, the odds ratio for lower FMD levels was reduced by 12.1 % per 1 pg/ml increase in serum TRAIL concentration after adjustment for multivariate metabolic factors [OR (95 % CI); 0.879 (0.721-0.973)]. Circulating TRAIL level decreased in newly diagnosed sHT patients and is positively associated with endothelial function, suggesting that circulating TRAIL level may be a protective marker of endothelial function in sHT patients.

Effects of restoration of the euthyroid state on epicardial adipose tissue and carotid intima media thickness in subclinical hypothyroid patients

Epicardial adipose tissue (EAT) thickness is a novel cardiovascular risk indicator, whereas carotid intima media thickness (CIMT) is a known marker of subclinical atherosclerosis. The aim of this study was to measure EAT thickness and CIMT in subclinical hypothyroid (SCH) patients and to determine the effect of restoration of the euthyroid state on these variables. The study included 43 patients with SCH (mean age: 35.2±10.7 years; F-M ratio: 42:1) and 30 healthy controls (mean age: 34.5±8.2 years; F-M ratio: 25:5). EAT thickness and CIMT were measured via conventional echocardiography and ultrasonography. Among the patients, 23 were followed up with L-thyroxine replacement until restoration of the euthyroid state and re-evaluated 6 months after baseline. Basal EAT thickness was higher in the SCH patients than in the controls (3.2±0.7 vs. 2.3±0.3 mm-p<0.0001), whereas CIMT was similar in both groups (0.50±0.09 vs. 0.48±0.04 mm). EAT thickness was correlated with CIMT in the patient group (r=0.39, p=0.01), but this correlation was not evident based on multivariate analysis when corrected for age and body mass index (r2=0.47 and p=0.0001 for the model). In the follow-up patient subgroup, both EAT thickness and CIMT decreased significantly following L-thyroxine treatment, when normal TSH levels were attained (3.4±0.7 vs. 2.3±0.5 mm-p=0.007 and 0.51±0.09 vs. 0.46±0.07 mm-p=0.01, respectively). EAT thickness was greater in the SCH patients than in controls, whereas CIMT was similar in both groups. Restoration of the euthyroid state with L-thyroxine treatment was associated with significant decreases in EAT thickness and CIMT in the group of patients that received L-thyroxine treatment and, as such, might reduce the cardiovascular risk associated with SCH.

The effect of L-thyroxine treatment on left ventricular functions in children with subclinical hypothyroidism

OBJECTIVE

The aim of this study was to search for evidence suggesting treatment for childhood subclinical hypothyroidism (SH) by evaluating left ventricular (LV) functions of children with SH by using M-mode and tissue Doppler echocardiography (TDE).

METHODS

Children with SH and euthyroid healthy children (control group) were enrolled in the study. At baseline and 6 months after euthyroidism was achieved, M-mode and TDE were performed and LV functions were evaluated. Pretreatment parameters of the SH group were compared with those of controls and post-treatment parameters.

RESULTS

31 children with SH and 32 euthyroid healthy children were enrolled in the study. The groups had similar age, gender, puberty and body mass index. Interventricular septum thickness and LV mass index, which are the parameters for LV morphology, were slightly increased in the SH group than in the controls (p<0.05). In TDE, children with SH had significant changes in LV diastolic (lower E'm, higher E/E'm ratio and longer isovolumic relaxation time) and systolic functions (lower isovolumic contraction time) compared with controls (p<0.05). Six months after euthyroidism was achieved, TDE showed a significant improvement of some of the diastolic and systolic parameters (p<0.05).

CONCLUSIONS

The results of this study showed that SH is associated with subclinical alterations in LV function, and LT4 replacement may improve LV systolic and diastolic parameters. However, since SH is usually a self-limiting process, these improvements in LV functions may simply be associated with the natural course of the disease and/or physiological linear growth of the children.

Clinical practice guidelines for the management of hypothyroidism

INTRODUCTION

Hypothyroidism has long been known for its effects on different organ systems, leading to hypometabolism. However, subclinical hypothyroidism, its most prevalent form, has been recently related to cardiovascular risk and also to maternal-fetal complications in pregnant women.

OBJECTIVES

In these clinical practice guidelines, several aspects of this field have been discussed with the clear objectives of helping physicians treat patients with hypothyroidism, and of sharing some of our Latin American-based clinical experience.

MATERIALS AND METHODS

The Latin American Thyroid Society commissioned a Task Force on Hypothyroidism to develop evidence-based clinical guidelines on hypothyroidism. A systematic review of the available literature, focused on the primary databases of MedLine/PubMed and Lilacs/SciELO was performed. Filters to assess methodological quality were applied to select the best quality studies. The strength of recommendation on a scale from A-D was based on the Oxford Centre for Evidence--based Medicine, Levels of Evidence 2009, allowing an unbiased opinion devoid of subjective viewpoints. The areas of interest for the studies comprised diagnosis, screening, treatment and a special section for hypothyroidism in pregnancy.

RESULTS

Several questions based on diagnosis, screening, treatment of hypothyroidism in adult population and specifically in pregnant women were posed. Twenty six recommendations were created based on the answers to these questions. Despite the fact that evidence in some areas of hypothyroidism, such as therapy, is lacking, out of 279 references, 73% were Grade A and B, 8% Grade C and 19% Grade D.

CONCLUSIONS

These evidence-based clinical guidelines on hypothyroidism will provide unified criteria for management of hypothyroidism throughout Latin America. Although most of the studies referred to are from all over the world, the point of view of thyroidologists from Latin America is also given.

Right ventricular and right atrial function and deformation in patients with subclinical hypothyroidism: a two- and three-dimensional echocardiographic study

BACKGROUND

We sought to investigate right ventricular (RV) function and deformation assessed by three-dimensional echocardiography (3DE) and speckle tracking in patients with subclinical hypothyroidism (SHT), and to evaluate the influence of levothyroxine (L-T₄) therapy on RV remodeling.

METHODS

We included 50 untreated women with SHT and 45 healthy control women matched by age. The L-T₄ therapy was prescribed to all SHT patients who were followed 1 year after euthyroid status was achieved. All study participants underwent laboratory analyses which included thyroid hormone levels, and complete two-dimensional echocardiography (2DE) and 3DE examinations.

RESULTS

3DE RV end-diastolic volume and ejection fraction were significantly reduced in the SHT patients before therapy in comparison with the healthy controls and treated SHT subjects. RV longitudinal strain, systolic, and early diastolic strain rates (SRs) were significantly decreased, whereas RV late diastolic SR was increased in the SHT patients before therapy when comparing with the controls. 2DE speckle tracking imaging revealed that L-T₄ substitution therapy significantly improved RV systolic mechanics, whereas RV diastolic deformation was not completely recovered. Right atrial (RA) function and deformation were significantly impacted by SHT. Replacement L-T₄ treatment improved but did not completely restore RA mechanics in the SHT patients.

CONCLUSION

RV and RA function and mechanics are significantly affected by SHT. L-T₄ therapy and 1-year maintenance of euthyroid status improved but did not completely recover RV and RA function and deformation in the SHT patients, which implies that right heart remodeling caused by SHT is not reversible in a 1-year period.

Subclinical hypothyroidism and left ventricular mechanics: a three-dimensional speckle tracking study

CONTEXT

Subclinical hypothyroidism (SHT) is associated with left ventricular (LV) remodeling. The LV mechanics has not been previously assessed by two- and three-dimensional (2DE and 3DE) speckle tracking imaging in the SHT patients.

OBJECTIVES

The objective of the study was to investigate LV mechanics by 2DE and 3DE speckle tracking in the SHT patients and evaluate the influence of levothyroxine therapy on LV remodeling.

DESIGN

We conducted a prospective study. All SHT patients received levothyroxine therapy and were followed up for 1 year after the euthyroid state had been achieved.

SETTING

The study was performed at a university hospital.

PATIENTS

We included 54 untreated women with SHT and 40 healthy control women who were of similar age.

MAIN OUTCOME MEASURES

The 2DE strain and strain rates, 3DE volumes, 3DE strain, and thyroid hormones levels were assessed.

RESULTS

The 2DE LV longitudinal and circumferential strain and systolic and early diastolic strain rates were significantly decreased in the SHT patients before therapy in comparison with the controls or the SHT patients after therapy. The 3DE LV cardiac output and ejection fraction were significantly reduced in the SHT patients at baseline compared with the controls or patients after 1 year of treatment. The 3DE LV longitudinal and radial strains were significantly lower in the SHT group before treatment in comparison with the controls or patients after therapy, whereas the 3DE LV circumferential and area strains gradually increased from untreated SHT patients, among the treated SHT patients, to the controls.

CONCLUSION

SHT significantly affects LV deformation assessed by 2DE and 3DE speckle tracking. The improvement of LV mechanics after 1 year of levothyroxine treatment is significant but incomplete.

Subclinical hypothyroidism is associated with elevated high-sensitive C-reactive protein among adult Taiwanese

Subjects with subclinical hypothyroidism (SCH) are at increased risk for cardiovascular disease (CVD). High-sensitivity C-reactive protein (hsCRP) is one of the inflammatory markers related to CVD. It is unclear whether inflammation is a mechanistic intermediary between SCH and CVD. We aimed to investigate the association between SCH and hsCRP in a Taiwanese population. A baseline cohort of 2,494 participants over the age of 19 was recruited in Taiwan from 2006 to 2008. SCH was defined as a serum thyroid-stimulating hormone (TSH) level of 5.61-19.9 mIU/L with normal thyroxine concentrations (a total T4 level of 4.9-12.0 μg/dL). Euthyroidism was defined as a serum TSH level of 0.34-5.60 mIU/L. HsCPR was grouped using quartiles. Multiple logistic and linear regression analyses were used to evaluate the relationship between hsCRP and SCH. After adjusting for gender and betel nut chewing, stepwise multiple logistic regression analyses revealed that hsCRP groups were significantly associated with SCH. Compared to the lowest hsCRP quartile, the adjusted odds ratio of having SCH for hsCRP quartile II, III, and IV were 1.38 (0.48-3.98), 1.48 (0.56-3.96), and 2.59 (1.01-6.67), respectively. The significant increase in odds ratios for SCH in progressive hsCRP quartiles reveals a dose-response effect (p < 0.05). Moreover, stepwise multiple linear regression analyses showed that hsCRP was significantly positively associated with serum TSH level after adjusting for potential confounders. Adult Taiwanese with SCH were associated with elevated hsCRP quartiles.

Left and right ventricular structure and function in subclinical hypothyroidism: the effects of one-year levothyroxine treatment

BACKGROUND

The aim of this study was to investigate left ventricular (LV) and right ventricular (RV) structure, function, and mechanics in patients with subclinical hypothyroidism (SHT), and to evaluate the effect of a 1-year levothyroxine treatment.

MATERIAL AND METHODS

We compared 45 untreated women with subclinical hypothyroidism and 35 healthy control women matched by age. All the subjects underwent laboratory analyses, which included a thyroid hormone levels (free T3, free T4, and TSH) test, and a complete 2-dimensional echocardiographic study. All the SHT patients received levothyroxine therapy and were followed for a year after euthyroid state was achieved.

RESULTS

The LV mass index in the SHT participants before and after replacement therapy was significantly higher than in controls. In the SHT patients before the treatment, LV diastolic function and global function estimated by the Tei index were significantly impaired, whereas the LV systolic function was decreased. The results show that LV mechanics was significantly impaired in the SHT patients at baseline. Additionally, the SHT participants before levothyroxine substitution had increased RV wall thickness and significantly impaired RV diastolic and global function in comparison with the controls or the SHT subjects after the treatment. Furthermore, RV mechanics was also significantly deteriorated in the SHT patients before the treatment.

CONCLUSIONS

Subclinical hypothyroidism significantly affected LV and RV structure, systolic, diastolic and global function, and LV and RV mechanics. Levothyroxine replacement therapy significantly improved cardiac structure, function, and mechanics in the SHT patients.

Subclinical hypothyroidism in grown-up congenital heart disease patients

Subclinical hypothyroidism usually is asymptomatic, but it can be associated with various adverse cardiologic outcomes. With the objective of gaining insight into the role of thyroid-stimulating hormone (TSH) in congenital heart abnormalities, this study measured serum TSH concentrations in different subtypes of grown-up congenital heart disease (GUCHD) patients. Serum TSH (reference range, 0.34-5.6 mIU/L), creatinine, cholesterol, C-reactive protein (CRP), N-terminal proB-type natriuretic peptide (NT-pro-BNP), and 24-h proteinuria were measured in 249 GUCHD patients. Of 24 GUCHD patients (9.6 %) with a TSH level higher than 5.6 mUI/L, nine were cyanotic (37.5 %) and seven (29.1 %) had Down syndrome. The GUCHD patients with serum TSH exceeding 5.6 mIU/L had a significantly higher level of serum NT-pro-BNP (195.1 [0.28; 5,280.3] vs 57.6 [0.00; 929.8]; p = 0.001) and CRP (0.30 [0.06; 1.87] vs 0.16 [0.00; 1.40]; p = 0.011] than those with a TSH level of 5.6 mIU/L or lower. No significant differences were found in serum creatinine, lipids, or 24-h proteinuria between the two groups. The T4 concentrations in the GUCHD patients with TSH exceeding 5.6 mIU/L were within the normal range (0.89 ± 0.23 ng/dL). In the multivariate analysis, cyanosis (odds ratio [OR], 6,399; 95 % confidence interval [CI] 2,296-17,830; p < 0.001), Down syndrome (OR, 6,208; 95 % CI, 1,963-19,636; p = 0.002), and NT-pro-BNP concentrations (OR, 1,001; 95 % CI, 1,000-1,002; p < 0.026) proved to be risk factors for TSH levels higher than 5.6 mIU/L. Because subclinical hypothyroidism entails a cardiovascular risk, the authors postulate that TSH screening should be included in the routine follow-up evaluation of GUCHD patients with cyanosis or Down syndrome.

Consenso brasileiro para a abordagem clínica e tratamento do hipotireoidismo subclínico em adultos: recomendações do Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia

INTRODUÇÃO: O hipotireoidismo subclínico (HSC), definido por concentrações elevadas do TSH em face de níveis normais dos hormônios tireoidianos, tem elevada prevalência no Brasil, particularmente entre mulheres e idosos. Embora um número crescente de estudos venha associando o HSC com maior risco de doença arterial coronariana e de mortalidade, não há ensaio clínico randomizado sobre o benefício do tratamento com levotiroxina na redução dos riscos e o tratamento permanece controverso. OBJETIVO: Este consenso, patrocinado pelo Departamento de Tireoide da Sociedade Brasileira de Endocrinologia e Metabologia e desenvolvido por especialistas brasileiros com vasta experiência clínica em tireoide, apresenta recomendações baseadas em evidências para uma abordagem clínica do paciente com HSC no Brasil. MATERIAIS E MÉTODOS: Após estruturação das questões clínicas, a busca das evidências disponíveis na literatura foi realizada inicialmente na base de dados do MedLine-PubMed e posteriormente nas bases Embase e SciELO - Lilacs. A força da evidência, avaliada pelo sistema de classificação de Oxford, foi estabelecida a partir do desenho de estudo utilizado, considerando-se a melhor evidência disponível para cada questão e a experiência brasileira. RESULTADOS: Os temas abordados foram definição e diagnóstico, história natural, significado clínico, tratamento e gestação, que resultaram em 29 recomendações para a abordagem clínica do paciente adulto com HSC. CONCLUSÃO: O tratamento com levotiroxina foi recomendado para todos os pacientes com HSC persistente com níveis séricos do TSH > 10 mU/L e para alguns subgrupos especiais de pacientes.

Diagnosis of subclinical central hypothyroidism in patients with hypothalamic-pituitary disease by Doppler echocardiography

OBJECTIVE

The diagnosis of subclinical central hypothyroidism in hypothalamic-pituitary patients cannot be established by serum markers of thyroid hormone action. Myocardial function by echocardiography has been shown to reflect thyroid hormone action in primary thyroid dysfunction. We evaluated the performance of echocardiography in diagnosing subclinical central hypothyroidism.

DESIGN

Cross-sectional and before and after.

METHODS

Echocardiography and serum thyroid hormones were assessed in overt primary (n=20) and central (n=10) hypothyroidism, subclinical primary hypothyroidism (n=10), hypothalamic-pituitary disease with normal free thyroxine (FT(4); n=25), and controls (n=28). Receiver operating characteristic (ROC) curves were generated using overt hypothyroidism patients and selected cut-off values were applied to detect both primary and central subclinical hypothyroidism. After levothyroxine (l-T(4)) intervention, patients were echocardiographically reevaluated at predefined targets: normal thyrotropin (TSH) in primary hypothyroidism, normal FT(4) in overt central hypothyroidism, and higher than pretreatment FT(4) in echo-defined subclinical central hypothyroidism.

RESULTS

Parameters with highest areas under the ROC curves (area under the curve (AUC) ≥0.94) were as follows: isovolumic contraction time (ICT), ICT/ejection time (ET), and myocardial performance index. Highest diagnostic accuracy (93%) was obtained when at least one parameter was increased (positive and negative predictive values: 93%). Hypothyroidism was echocardiographically diagnosed in eight of ten patients with subclinical primary hypothyroidism and in 14 of 25 patients (56%) with hypothalamic-pituitary disease and normal serum FT(4). Echocardiographic abnormalities improved significantly after l-T(4) and correlated (0.05<P<0.001) with changes in FT(4) (-0.62<r<-0.55) and TSH (0.63<r<0.68) in primary hypothyroidism and with FT(4) in central hypothyroidism (-0.72<r<-0.50).

CONCLUSION

Echocardiography can be useful in diagnosing subclinical central hypothyroidism in patients with hypothalamic-pituitary disease.

A review of the evidence for and against increased mortality in hypothyroidism

The lifetime risk of overt hypothyroidism is around 5%, and this disease is usually preceded by subclinical hypothyroidism, which has an even higher prevalence (estimated to be up to 9%). Hypothyroidism has been linked with cardiac dysfunction, atherosclerosis, hypertension and coagulopathy. Intuitively, this increased morbidity is expected to shorten patients' lifespan, but definitive data are lacking on whether either of these hypothyroid states (particularly overt hypothyroidism) increase mortality. Study findings are inconsistent and, overall, the pooled data do not demonstrate increased mortality in patients with either subclinical or overt hypothyroidism. However, none of the available studies was adequately designed to answer this question. This Review discusses major shortcomings in those studies, such as population dissimilarities, hypothyroid state classification and misclassification, the inclusion of nonthyroidal illness, drug interference from concurrent therapies, serious comorbidities (for example, cardiovascular disease), differences in duration of follow-up and the number of levothyroxine-treated individuals. Taken together, the data exhibit little evidence of systematic bias and no strong scientific proof of increased mortality related to either subclinical or overt hypothyroidism. Future studies, however, should take the above-mentioned shortcomings and potential genetic confounding into consideration.

Impact of subclinical hypothyroidism treatment in systolic and diastolic cardiac function

OBJECTIVE: To evaluate the effects of levothyroxine (L-T4) replacement in echocardiographic parameters of middle-aged women with subclinical hypothyroidism (SH). SUBJECTS AND METHODS: This was a randomized, double-blind, placebo-controlled study. Echocardiographic evaluation was carried out at baseline and one year after restoration of euthyroidism. Thirty-three women with SH were assigned to one of two groups (L-T4 or placebo). RESULTS: The two groups had similar basal characteristics. There was a significant deterioration of left ventricular Tei index after one year of placebo use, which differed from the effect of L-T4 replacement (+0.086 ± 0.092 vs. -0.014 ± 0.012; p = 0.047). There was also a slight reduction in cardiac output and cardiac index with placebo use, which was not different from L-T4 effect. CONCLUSION: Results suggest a positive impact of L-T4 replacement in cardiac function of middle-aged women with SH.

The evaluation of diastolic dysfunction with tissue Doppler echocardiography in women with subclinical hypothyroidism and the effect of L-thyroxine treatment on diastolic dysfunction: a pilot study

Background. Subclinical hypothyroidism (SH) predominantly affects women. The necessity of treatment in SH is controversial. Objective. We aimed to investigate the response of diastolic dysfunction to thyroid hormone replacement therapy (THRT) in women. Methods and Results. Twenty-two female subjects with SH and 20 euthyroid female controls were enrolled. Baseline and follow-up biochemical, hormonal, and echocardiographic evaluations were performed. Repeat echocardiograms were performed three months after the achievement of a euthyroid status with THRT. Mean baseline myocardial performance index (MPI) was 0.27 ± 0.08 in the SH group, and 0.22 ± 0.06 in the control group (P = 0.03). MPI did not change significantly after THRT. Pulsed-wave Doppler findings were not different among the groups. However, tissue Doppler-derived mitral annular E' velocities were significantly lower in the SH group. A moderate but significant improvement was observed in E' velocities after THRT (13.2 ± 3.87 versus 14.53 ± 2.75, P = 0.04). We also observed left ventricular concentric remodeling in SH patients which was reversible with THRT. Conclusions. Tissue Doppler echocardiography may be a useful tool for monitoring the response of diastolic dysfunction to thyroid hormone replacement therapy in patients with SH. Our findings suggest that THRT may reverse diastolic dysfunction in women with SH.

Hypothyroidism in patients with Bipolar I Disorder treated primarily with lithium

Aims – This study evaluated the frequency and clinical significance of abnormal Thyroid Stimulating Hormone (TSH) and Free Thyroxine Index (FTI) in patients with bipolar I disorder treated primarily with lithium. Method – We evaluated the medical records of 143 participants in the Pittsburgh study of Maintenance Therapies in Bipolar Disorder who did not have a thyroid abnormality at entry. Results – Thirty-six percent of the 143 patients developed abnormal TSH and/or FTI values. Thirty-eight percent of the 135 patients who received lithium developed abnormal TSH and/or FTI, spent significantly longer time in the acute treatment phase (t = -3.6, df = 133, p = .0004), and had significantly higher mean Hamilton Scale for Depression scores over the course of the maintenance phase (t = -2.3, df = 71.6, p = .03). Time on lithium and development of abnormal TSH and/or FTI were positively correlated (r = .25, p = .004). Conclusions – Thyroid dysfunction can be frequent in patients exposed to lithium treatment for bipolar I disorder; it also appears to be correlated with a slower response to acute treatment, and may be related to poorer quality of long-term remission. A prospective study is needed to confirm our findings and determine whether more aggressive thyroid replacement can optimize thyroid function to facilitate clinical recovery.

Declaration of Interest: Supported in part by National Institute of Mental Health Grants MH 029618 (Drs. Frank and Fagiolini) and MH 030915 (Drs. Kupfer and Fagiolini), and the Bosin Memorial Fund of The Pittsburgh Foundation (Drs. Fagiolini, Kupfer, Cook, Scott, Novick and Frank). Dr. Fagiolini is on the advisory board and a consultant to Pfizer Inc, and Bristol Myers Squibb, and is on the speaker bureau of Bristol Myers Squibb, Eli Lilly Italy, Pfizer Inc, and Shire. Dr. Frank is on the advisory board of Pfizer Inc. and Eli Lilly & Company, and is a consultant to Pfizer Italia and Sender Amerique. Dr. Kupfer is on the advisory board of Pfizer, Inc., Forest Pharmaceuticals, Inc., and Solvay-Wyeth Pharmaceuticals, and is a consultant to Servier Amerique.

Thyroid function and left ventricular structure and function in the Framingham Heart Study

BACKGROUND

Thyroid hormone acts on the heart and peripheral vasculature in multiple ways. Even in patients with subclinical hypo- or hyperthyroidism, subclinical alterations in left ventricular (LV) structure and function may be associated with important clinical effects. Our objective was to determine whether thyroid function is related to echocardiographic indices of LV structure and function.

METHODS

Cross-sectional association of serum thyroid-stimulating hormone (TSH) with two-dimensional-guided M-mode echo LV dimensions and function. Participants were 1376 Framingham Heart Study participants (61% women, mean age 69 years) who attended a routine examination 1979-1981. We excluded participants with myocardial infarction or heart failure, renal insufficiency, and missing data, and those using thyroid hormone or antithyroid medications. Serum TSH was measured 1977-1979. The following echocardiographic measurements were analyzed both as continuous variables and dichotomized at the top quintile: LV end-diastolic dimensions, LV wall thickness, LV mass, LV fractional shortening (an indicator of systolic function), and left atrial diameter. Sex-specific multiple regression models were adjusted for age, height, weight, blood pressure, heart rate, total to high-density lipoprotein cholesterol ratio, and the presence of diabetes, hypertension treatment, and valve disease.

RESULTS

In multivariable linear models, log-TSH was not related to LV mass, LV wall thickness, or left atrial size in either sex, or to LV systolic function in men. Log-TSH had a borderline inverse association with fractional shortening (p = 0.06) in women. In multivariable logistic models, women with TSH <0.5 mU/L (n = 81) had a greater odds of being in the highest quintile of fractional shortening compared to euthyroid subjects (odds ratio 2.2, 95% confidence interval 1.3-3.8, p = 0.01).

CONCLUSIONS

In our moderate-sized community-based sample, TSH concentration was not associated with LV structure in either sex, but was inversely related to LV contractility, consistent with the known inotropic effects of thyroid hormone.

Subclinical hypothyroidism effects on cardiac function

To evaluate heart function in subclinical hypothyroid women in comparison with healthy subjects, a prospective study was performed on newly detected subclinical hypothyroid women presenting to endocrinology clinic of Tabriz Sina Hospital from October 2007 to February 2008. Thirty five women with Subclinical Hypothyroidism (SH) in case group were matched with 35 healthy euthyroid women in control group. All patients in both groups were studied by two dimensional echocardiography and Tissue Doppler Imaging (TDI) in Tabriz Shahid Madani Hospital. The FT4 and TSH levels were measured. Comparison of TDI results in Right Ventricle (RV) showed the significantly lower mean T(v) excursion in case group with no significant difference in other parameters. In Left Ventricle (LV), the mean A(m), A(v) and E(v)/E(m) were significantly higher and E/A was lower in the case group, but there was no significant difference in other parameters. No RV diastolic dysfunction was documented in both groups. There was no case with LV systolic dysfunction in both groups. There were 21 (60%) patients with LV diastolic dysfunction in the case group comparing with 11 (31.4%) cases in the control group (p = 0.016, OR = 0.306). Frequency of LV diastolic dysfunction was significantly higher in the case group in patients aged > or = 40 years (94.1% vs. 53.3%; p = 0.013). There was no case of pericardial effusion in the studied population. According to our results, SH may cause LV diastolic dysfunction. Likewise, minor RV systolic dysfunction might be seen in these patients.

Effect of levothyroxine replacement on exercise performance in subclinical hypothyroidism

Although muscle metabolism and exercise capacity seem to be affected in patients with subclinical hypothyroidism, there is little evidence indicating improvement of the exercise tolerance due to levothyroxine (L-T(4)) replacement. The aim of the present study was to verify possible cardiopulmonary changes during exercise in patients with subclinical hypothyroidism on L-T(4) replacement with a normal serum TSH for six months. Twenty-three patients with subclinical hypothyroidism were randomized into treated (no.=11) and untreated (no.=12) patients. A cardiopulmonary test was performed with a treadmill, using the modified Balke protocol. Heart rate, oxygen uptake, minute ventilation and other cardiopulmonary parameters were assessed at the 5th minute of exercise. FT4 levels increased while TSH normalized after hormone replacement. Oxygen uptake decreased significantly after hormone replacement (24.1+/-6.3 vs 17.1+/-4.2 ml x kg x min(-1); p=0.03).Minute ventilation also showed an enhanced performance in treated patients (28.0+/-8.1 vs 23.5+/-5.6 l x min(-1); p=0.03), as did the heart rate (128+/-17 vs 121+/-17 bpm; p=0.03). There were no changes in the untreated group. The results demonstrate that submaximal cardiopulmonary exercise performance improved after six months of TSH normalization and this improvement can help enhance the ability to carry out daily life activities in patients with subclinical hypothyroidism.

Circulating IGF-I levels are associated with increased biventricular contractility in top-level rowers

BACKGROUND

The intensive physical activity is often associated with cardiac changes.

OBJECTIVES

(i) To evaluate the IGF-I system and myocardial structure and function by standard Doppler echocardiography and Tissue Doppler in athletes and sedentary controls; and (ii) to determine any relationship between IGF-I system and echocardiographic parameters.

METHODS

Nineteen male top-level rowers and 19 age-matched healthy sedentary male controls underwent blood determination of fasting serum IGF-I, IGFBP-3 and acid-labile subunit levels and standard Doppler echocardiography combined with pulsed Tissue Doppler of posterior septal wall, left ventricular (LV) lateral mitral annulus and right ventricular (RV) tricuspid annulus. Myocardial presystolic (PS(m)), systolic (S(m)), the ratio of early diastolic (E(m)) to atrial (A(m)) velocities as well as myocardial time intervals were calculated.

RESULTS

Rowers had higher serum IGF-I levels (P = 0.04), higher biventricular cavity dimensions and wall thicknesses compared to controls. They also had better LV and RV myocardial function than controls. In the rowers, IGF-I was associated with LV ejection fraction (r = 0.50, P = 0.03), RV PS(m) velocity (r = 0.55, P = 0.01) and with RV myocardial precontraction time (r = -0.57, P = 0.01). These associations remained significant after adjusting for age and heart rate.

CONCLUSIONS

Top-level athletes showed higher IGF-I levels and a better myocardial performance than controls, particularly for the RV systolic activity. The independent correlations between IGF-I and systolic parameters of the left (ejection fraction) and right (PS(m) velocity and precontraction time) ventricles may possibly indicate a role of IGF-I system in the modulation of myocardial inotropism in athletes. Further studies are needed to confirm this hypothesis.

Cardiac functions in children with coeliac disease during follow-up: insights from tissue Doppler imaging

BACKGROUND

The identification of a coeliac disease in patients with idiopathic dilated cardiomyopathy raises critical questions on the relationship between the two entities. But cardiac functions have not been studied in patients with coeliac disease. The present study was undertaken to assess cardiac functions by Tissue Doppler Echocardiography in patient with coeliac disease.

METHODS

We studied 45 clinically stable patients; twenty-five patients with positive serum IgA Antiendomysial Antibody levels (Group 1), twenty patients with negative serum IgA Antiendomysial Antibody levels (Group 2) at the time of echocardiographic study. Control group consisted of 30 healthy children free of any disease.

RESULTS

Myocardial systolic wave velocity of the mitral annulus was significantly lower (p<0.001), myocardial precontraction and contraction time were slightly longer in Group 2 when compared control group (p=0.015, p=0.044, respectively). There was a negative correlation between the serum IgA Antiendomysial Antibody levels titers and myocardial systolic wave levels of all patients included in the study (r = -0.633; p<0.001). A myocardial systolic wave velocity of <8.9 cm/s had a 92% sensitivity and 80% specificity in predicting serum IgA Antiendomysial Antibody levels positive patients.

CONCLUSIONS

We detected subclinical systolic dysfunction of the left ventricle in children with coeliac disease in whom serum IgA Antiendomysial Antibody reactivity is prominent. Tissue Doppler echocardiography provides a quantifiable indicator useful for cardiac monitoring of disease during follow up.

The clinical significance of subclinical thyroid dysfunction

Subclinical thyroid disease (SCTD) is defined as serum free T(4) and free T(3) levels within their respective reference ranges in the presence of abnormal serum TSH levels. SCTD is being diagnosed more frequently in clinical practice in young and middle-aged people as well as in the elderly. However, the clinical significance of subclinical thyroid dysfunction is much debated. Subclinical hyper- and hypothyroidism can have repercussions on the cardiovascular system and bone, as well as on other organs and systems. However, the treatment and management of SCTD and population screening are controversial despite the potential risk of progression to overt disease, and there is no consensus on the thyroid hormone and thyrotropin cutoff values at which treatment should be contemplated. Opinions differ regarding tissue effects, symptoms, signs, and cardiovascular risk. Here, we critically review the data on the prevalence and progression of SCTD, its tissue effects, and its prognostic implications. We also examine the mechanisms underlying tissue alterations in SCTD and the effects of replacement therapy on progression and tissue parameters. Lastly, we address the issue of the need to treat slight thyroid hormone deficiency or excess in relation to the patient's age.

Thyroid stimulating hormone and left ventricular function

CONTEXT

Overt hypo- and hyperthyroidism are associated with cardiac disease, whereas this relation is more uncertain regarding subclinical thyroid dysfunction.

OBJECTIVE

The objective was to assess the relation between serum TSH level and cardiac function.

DESIGN

We conducted a cross-sectional epidemiological study and a nested case-control study.

SETTING

The study was performed at a university hospital.

SUBJECTS

A total of 2035 subjects were included in the epidemiological study and 204 subjects in the nested case-control study (serum TSH < 0.50, 0.50-3.49, and 3.50-10.0 mIU/liter in 20, 118, and 66 subjects, respectively, all with normal serum free T(4) and free T(3) levels).

MAIN OUTCOME MEASURES

Left ventricular mass by body surface area (LVMI) and indices of left ventricular function, as assessed by conventional and pulsed-wave tissue Doppler (PWTD) echocardiography, were recorded.

RESULTS

No significant relation was found between serum TSH level and LVMI. In the nested case-control study, the subjects with serum TSH 3.50-10.0 mIU/liter had no signs of cardiac dysfunction. However, the PWTD data showed higher velocities at all measurement sites in the subjects with serum TSH less than 0.50 mIU/liter as compared with the euthyroid group.

CONCLUSIONS

With the possible exception of overt hypo- and hyperthyroidism, there is no significant association between serum TSH level and LVMI. Subjects with subclinical hypothyroidism, in whom the mean serum TSH level is slightly above the reference range, appear to have normal cardiac function, whereas subjects with serum TSH levels less than 0.5 mIU/liter appear to have changes in myocardial velocities detected by PWTD.

Cardiovascular effects of mild hypothyroidism

The cardiovascular risk is increased in patients with overt hypothyroidism, and several potential cardiovascular risk factors were similarly reported in patients with subclinical hypothyroidism. Only recently have more data become available about the effects of mild hypothyroidism on the cardiovascular system. An impaired left ventricular diastolic function, which is characterized by slowed myocardial relaxation and impaired ventricular filling, is the most consistent cardiac abnormality in patients with mild thyroid hormone deficiency. Impaired left ventricular diastolic function on effort was also documented by radionuclide ventriculography. Studies performed by ultrasonic myocardial textural analysis suggest an altered myocardial composition in patients with mild hypothyroidism. Moreover, pulsed tissue Doppler analysis revealed that patients with mild hypothyroidism had changes in myocardial time intervals in several left ventricular segments. Finally, alterations in cardiac hemodynamic were documented by cardiac magnetic resonance imaging in presence of mild disease. Vascular function is impaired in patients with mild and subclinical hypothyroidism, as documented by the increase in systemic vascular resistance and arterial stiffness and by the impaired endothelial function. The negative effect induced by mild hypothyroidism on cardiovascular system can be reverted restoring euthyroidism with levothyroxine (L-T4) therapy. Based on the data available, it appears that L-T4 replacement should be considered in patients with mild hypothyroidism in presence of associated cardiovascular risk factors in the attempt to reverse these negative prognostic factors and improve the cardiovascular risk.

Hypothyroidism following Hemithyroidectomy for Benign Nontoxic Thyroid Disease

Hypothyroidism following hemithyroidectomy for benign nontoxic thyroid disease is an underappreciated phenomenon. Up until recently, it was common practice for physicians to place post-hemithyroidectomy patients on thyroid suppression therapy during the immediate postoperative period. That practice began to fall out of favor as a result of two developments: (1) the publication of data that put into question the efficacy of levothyroxine therapy for preventing recurrent disease or thyroid growth and (2) a heightened awareness of the morbidity associated with levothyroxine. We conducted a retrospective chart-review study of 58 patients with benign nontoxic thyroid disease who had undergone hemithyroidectomy from 1994 through 2003 at one institution. Of these 58 patients, 14 (24.1%) had become hypothyroid after surgery, including 7 who had been so diagnosed 1 month postoperatively and 6 at 2 months. The remaining 44 patients were euthyroid. The mean preoperative serum thyroid-stimulating hormone (TSH) levels in the hypothyroid and the euthyroid groups were 2.39 and 1.07 μIU/ml, respectively—a statistically significant difference (p < 0.0001). A tissue diagnosis consistent with chronic inflammation (lymphocytic thyroiditis or Hashimoto's thyroiditis) was found in 50.0% of the hypothyroid patients, compared with only 6.8% of the euthyroid patients—again, a significant difference (p < 0.001). No significant difference was seen between the two groups with respect to age, sex, or the weight of the resected gland. We conclude that hypothyroidism after hemithyroidectomy is not an uncommon occurrence. Apparent risk factors include a high mean preoperative serum TSH level and tissue pathology consistent with chronic inflammation. It may be wise to follow patients with these identifiable risk factors more closely during the postoperative period; monitoring should include scheduled serial serum TSH draws.

Effects of thyroxine therapy on right ventricular systolic and diastolic function in patients with subclinical hypothyroidism: a study by pulsed wave tissue Doppler imaging

INTRODUCTION

The effects of l-thyroxine (l-T(4)) replacement for subclinical hypothyroidism (SH) on right ventricle (RV) functions has not been previously studied by means of pulsed wave tissue Doppler imaging (PWTDI). We investigated the effects of l-T(4) therapy on RV function in patients with SH using PWTDI.

PATIENTS AND METHODS

Fifty-three patients with newly diagnosed SH and 25 controls were evaluated by standard echocardiography and PWTDI. After euthyroidism was restored by l-T(4), measurements were repeated. Myocardial systolic wave (S(m)) velocity, isovolumic acceleration (IVA), myocardial precontraction time (PCT(m)), and PCT(m) to contraction time (CT(m)) ratio were calculated as systolic indices. Early (E(m)) velocity, late (A(m)) velocity, E(m) to A(m) ratio, and myocardial relaxation time (RT(m)) were determined as diastolic measurements.

RESULTS

S(m) was similar in patients and controls, whereas IVA was significantly lower in patients with SH (P < 0.001). SH patients had significantly decreased E(m) velocity, whereas A(m) velocity and E(m) to A(m) ratio did not differ. PCT(m) and RT(m) were significantly longer, and PCT(m) to CT(m) ratio was significantly higher in patients (P = 0.002, P = 0.002, P < 0.001, respectively). S(m) velocities were similar before and after l-T(4) replacement, whereas IVA significantly increased after therapy (P < 0.001). E(m) tended to increase (P = 0.05), whereas A(m) and E(m) to A(m) ratio were not changed. PCT(m), PCT(m) to CT(m) ratio, and RT(m) decreased significantly (P < 0.001 for all).

CONCLUSIONS

SH is associated with RV systolic and diastolic dysfunction, and l-T(4) treatment improves these abnormalities. PWTDI, especially IVA, may be a suitable tool for the early detection of RV systolic dysfunction.

Effect of L-thyroxine treatment on left ventricular function in subclinical hypothyroidism

Aim of this study was to investigate the effects of thyroxine treatment on myocardial regional left ventricular (LV) systolic and diastolic function in patients with subclinical hypothyroidism (SH) by tissue Doppler imaging (TDI). Forty-two patients (29 women and 13 men; mean age 52.2+/-15.1 years) with SH, as judged by elevated serum thyroid-stimulating hormone (TSH) levels (>3.6 mIU/l; range, 3.8-12.0) and free thyroid hormones (FT4 and FT3) within the normal range, and 30 euthyroid volunteers (21 women and nine men; mean age 50.4+/-17.1 years) underwent standard echocardiography and TDI-derived early (Em) and late (Am) diastolic velocities, systolic (Sm) velocity, and isovolumetric relaxation time (IVRTm). Patients were randomly assigned to receive or not L-thyroxine replacement therapy. All patients returned after 6 months to repeat thyroid function tests and the evaluation of all parameters. No significant differences were seen in the Sm peak between SH and control groups. Respect to controls, SH patients exhibited a lower Em, a higher Am, and, subsequently, a reduced Em/Am ratio of both lateral wall (LW) and interventricular septum (IVS) (P<0.001 for both). The IVRTm was distinctly longer in SH patients, as compared to controls (P<0.001). At 6 months, L-thyroxine-treated patients showed a significant increase of Em (P<0.01) and a subsequent increase of the Em/Am ratio (P<0.01), whereas IVRTm significantly reduced (P<0.05). No significant change in any of these parameters was observed in the untreated group. Our data suggest that SH is associated with a subtle, reversible impairment of myocardial function. TDI analysis detects and extends these functional defects by displaying alterations in regional myocardial function. L-T4 replacement therapy should be advised for these patients with the aim to correct preclinical cardiac dysfunction and prevent the development of clinically significant myocardial dysfunction.

Usefulness of Pulsed-Wave Tissue Doppler Echocardiography for the Assessment of the Left and Right Ventricular Function in Patients with Clinical Hypothyroidism

Clinical hypothyroidism (HT) is often associated with cardiovascular disorders, such as endothelial and myocardial dysfunction. Previous studies have explored left ventricular (LV) function using pulsed-wave tissue Doppler echocardiography (TDE) in HT. However, no study has utilized this technique in the assessment of right ventricular (RV) function in HT. Accordingly, we investigated the effects of clinical HT on LV and RV function by TDE. The study subjects included 35 newly diagnosed HT patients and 32 healthy normal controls. For each subject, serum FT3, FT4, TT3, TT4, and thyroid stimulating hormone (TSH) levels were measured, and standard echocardiography and TDE were performed. No statistically significant difference was found between patients and controls with regard to age, gender, body mass index, heart rate, and blood pressure. Compared to controls, TSH levels were significantly higher, and TT4 and FT4 levels were significantly lower. TDE showed that patients had significantly lower early diastolic tricuspid annular velocity (Ea) and early/late (Ea/Aa) diastolic tricuspid annular velocity ratio (P < 0.001 and P < 0.001, respectively), and significantly longer isovolumetric relaxation time (P < 0.001) than those of the controls. Aa, Sa, isovolumetric contraction time, and ejection time did not significantly differ. In addition, a significant relationship between some TDE indexes, and thyroid hormones (TT4 and FT4) and TSH was observed. We showed that patients with clinical HT are associated with impaired RV diastolic function, in addition to impaired LV diastolic function using TDE.

Evaluation of Right Ventricular Function in Patients with Thyroid Dysfunction

BACKGROUND

Thyroid gland dysfunction affects the structure and function of the heart. Tissue Doppler echocardiography is a new technique, and it has been used frequently in the evaluation of ventricular function. In the present study, right ventricular function was assessed in patients with overt or subclinical hypothyroidism and hyperthyroidism and in healthy subjects using the tissue Doppler method, and results were compared.

PATIENTS AND METHODS

20 healthy subjects and 63 patients diagnosed with overt and subclinical hypothyroidism and hyperthyroidism were included in the study. Annular and myocardial systolic peak velocities, early and late diastolic peak velocities, precontraction, total contraction and relaxation times of the right ventricle were recorded by tissue Doppler echocardiography. The results of the patients were compared to those of the controls.

RESULTS

Myocardial systolic velocity was significantly higher in patients with hyperthyroidism. Annular and myocardial late diastolic velocities were found to be significantly lower in patients with overt hypothyroidism. Annular precontraction time was increased in patients with overt and subclinical hypothyroidism. Myocardial precontraction time was decreased in patients with hyperthyroidism, and increased in patients with overt hypothyroidism patients. Annular relaxation time was increased in patients with overt hypothyroidism.

CONCLUSIONS

Right ventricular function is affected in patients with thyroid diseases. The tissue Doppler technique is a suitable tool to detect impairments in right ventricular function. There is a significant correlation between serum thyroid hormone levels and right ventricular velocities and time intervals.