Abnormal left ventricular longitudinal functional reserve assessed by exercise pulsed wave tissue Doppler imaging in patients with subclinical hypothyroidism

Left Ventricular Diastolic Dysfunction in Patients with Subclinical Hypothyroidism: A Single South Indian Tertiary Care Centre Study

Context Subclinical hypothyroidism (SCH) has been implicated in left ventricular diastolic dysfunction (LVDD).

Aims To study the association between SCH and LVDD.

Objectives To analyze the association between SCH and LVDD. To correlate the amount of LVDD with the serum thyroid-stimulating hormone (TSH) levels.

Settings and Design Single-center case–control study.

Methods and Material A case–control study was conducted between January 2020 and June 2021. A total of 36 cases of SCH were enrolled in the study and 36 age- and gender-matched euthyroid controls were included. Each individual's LV diastolic functioning was assessed by 2D echocardiography. LVDD was graded and compared between cases and controls.

Statistical Analysis Used The sample size was calculated to be 72 based on previous studies. Statistical analysis was performed using the IBM SPSS software version 20. A p-value of less than 0.05 was considered significant.

Results SCH was more commonly seen among females (75%) as compared with males (25%). Among cases, a majority of them (75%) had grade 1 SCH (i.e., TSH < 10 mU/L) and 25% of them had grade 2 SCH (i.e., TSH ≥ 10 mU/L). Among all the parameters assessed for LV diastolic function, the isovolumetric relaxation time and septal E/e' ratio was found to be significantly higher in cases than in controls and mitral E wave deceleration time (DT) significantly lower in cases. A statistically significant majority (72.2%) of the patients with SCH had some form of LVDD as compared with controls (30.5%)

Conclusions Walk-in outpatient department patients who opt for health check-up packages should be screened for SCH. SCH is statistically significantly associated with higher grades of LVDD as compared with age- and gender-matched euthyroid controls.

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.

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.

Subclinical hypothyroidism in childhood and adolescense

Subclinical hypothyroidism (SH) is defined as a serum thyroid-stimulating hormone (TSH) level above the reference range with normal serum free thyroxin (sT4) and free triiodothyronine (sT3) levels. The prevalence of SH in children and adolescents is reported between 1.7% and 9.5%. Hashimoto's thyroiditis is the most prevalent cause of SH in children. Although it has been suggested that SH is entirely an asymptomatic laboratory diagnosis, typical hypothyroid symptoms as well have been reported in some patients. Results of the adult studies on SH revealed that SH had unfavorable effects on cardiovascular system (atherosclerosis); metabolic parameters (dyslipidemia, insulin resistance, etc.); neuromuscular system; and cognitive functions in the long term. The number of studies investigating the effect of childhood SH on growth, bone maturation, lipid parameters, carbohydrate metabolism, neuromuscular system, and cognitive and cardiac function is limited. Knowledge about the natural history of SH is unclear even though there are numerous studies upon this subject. In children and adults, treatment of SH with L-T₄ is still a matter of debate, and there is no consensus on this issue yet.

Endobiogeny: a global approach to systems biology (part 1 of 2)

Endobiogeny is a global systems approach to human biology that may offer an advancement in clinical medicine based in scientific principles of rigor and experimentation and the humanistic principles of individualization of care and alleviation of suffering with minimization of harm. Endobiogeny is neither a movement away from modern science nor an uncritical embracing of pre-rational methods of inquiry but a synthesis of quantitative and qualitative relationships reflected in a systems-approach to life and based on new mathematical paradigms of pattern recognition.

New concept of myocardial longitudinal strain reserve assessed by a dipyridamole infusion using 2D-strain echocardiography: the impact of diabetes and age, and the prognostic value

AIMS

Although dipyridamole is a widely used pharmacological stress agent, the direct effects on myocardium are not entirely known. Diabetic cardiomyopathy can be investigated by 2D-strain echocardiography. The aim of this study was to assess myocardial functional reserve after dipyridamole infusion using speckle-tracking echocardiography.

METHODS

Seventy-five patients referred for dipyridamole stress myocardial perfusion gated SPECT (MPGS) were examined by echocardiography to assess a new concept of longitudinal strain reserve (LSR) and longitudinal strain rate reserve (LSRR) respectively defined by the differences of global longitudinal strain (GLS) and longitudinal strain rate between peak stress after dipyridamole and rest. Twelve patients with myocardial ischemia were excluded on the basis of MPGS as gold standard.

RESULTS

Mean LSR was -2.28±2.19% and was more important in the 28 (44%) diabetic patients (-3.27±1.93%; p=0.001). After multivariate analyses, only diabetes improved LSR (p=0.011) after dipyridamole infusion and was not associated with glycaemic control (p=0.21), insulin therapy (p=0.46) or duration of the disease (p=0.80). Conversely, age (p=0.002) remained associated with a decrease in LSR. LSSR was also correlated to age (p=0.005). Patients with a LSR<0% have a better survival after 15 months (log-rank p=0.0012).

CONCLUSION

LSR explored by 2D speckle-tracking echocardiography after dipyridamole infusion is a simple and new concept that provides new insights into the impact of diabetes and age on the myocardium with a potential prognostic value.

Subclinical hypothyroidism in the elderly: to treat or not to treat?

Aging is associated with a host of alterations in thyroid gland structure and function. Some of these changes have favorable effects on longevity, whereas others are maladaptive and contribute to a decline in health and quality of life. An area of particular controversy is the diagnosis and management of subclinical hypothyroidism in the elderly. The clinical diagnosis of hypothyroidism in the elderly is difficult, because many signs and symptoms associated with hypothyroidism are commonly present in euthyroid elderly individuals. The biochemical profile of subclinical hypothyroidism includes normal serum levels of thyroid hormones with mildly elevated serum thyrotropin concentrations in the range of 4.5 to 10 mIU/L. In this article, the epidemiology of subclinical hypothyroidism in the elderly is reviewed, the potential advantages of mild hypothyroidism in people over the age of 75 years are discussed, and some guidelines for screening and management of this common thyroid dysfunction are suggested.

Natural history, diagnosis and management of subclinical thyroid dysfunction

Subclinical thyroid dysfunction (STD) represents a condition of slight thyroid hormone excess or deficiency, which may be associated with important adverse effects. This review will focus on the natural history, diagnosis and management of subclinical thyroid dysfunction. Since STD is only detected as a thyroid stimulating hormone (TSH) abnormality, it is essential to exclude transient causes of abnormal serum TSH before treating this disorder. Treatment of subclinical hyperthyroidism (SHyper) is recommended in elderly patients with undetectable serum TSH for the increased risk of atrial fibrillation, osteoporosis and bone fractures and for the higher risk of progression to overt disease. Treatment of subclinical hypothyroidism should be considered in patients with serum TSH above 10 mU/L for the increased risk of progression to overt hypothyroidism and the increased risk of coronary heart disease and heart failure events, which have been documented in patients with TSH increase above 10 mU/L. About 75% of patients with STD have mild dysfunction. The mild form of STD (low but detectable serum TSH in SHyper and mild increased serum TSH between 5 and 9 mU/L in SHypo is associated with a minor risk of disease progression to overt dysfunction. The best treatment for STD remains controversial. Treatment of the mild form of STD should be considered after evaluating the patients' age, the adverse risk factors, the potential beneficial effects of treating this disorder and any underlying co-morbidities. Mild SHypo should be treated in infertile and pregnant women.

Persistence of mortality risk in patients with acute cardiac diseases and mild thyroid dysfunction

INTRODUCTION

There are no studies on the long-term prognostic role of abnormal thyrotropin value in patients with acute cardiac diseases. Aim of the study was to assess the incidence and persistence of risk of cardiac and overall deaths in patients with acute cardiac diseases.

METHODS

A total of 1026 patients (mean age: 67.7 years) were divided into 4 groups: (1) euthyroid (EU, n=579); (2) subclinical-like hypothyroidism (SLHYPO, n=68); (3) subclinical-like hyperthyroidism (SLHYPER, n=23) and (4) low-triiodothyronine syndrome (LowT3, n=356). Follow-up started from the day of thyroid hormone evaluation (mean follow-up: 30 months). The events considered were cardiac and overall deaths.

RESULTS

Survival rate for cardiac death was lower in SLHYPO and in LT3 than in EU (log rank test; χ(2)=33.6; P < 0.001). Survival rate for overall death was lower in SLHYPO, SLHYPER and LowT3 than in EU (48.3; P < 0.001). After adjustment for several risk factors, the hazard ratio for cardiac death was higher in SLHYPO (3.65; P=0.004) in LowT3 (1.88; P=0.032) and in SLHYPER (4.73; P=0.047). Hazard ratio for overall death was higher in SLHYPO (2.30; P=0.009), in LowT3 (1.63; P=0.017) and in SLHYPER than in EU (3.71; P=0.004). Hazards for SLHYPO, SLHYPER and LowT3 with respect to EU were proportional over the follow-up period.

CONCLUSION

In patients with acute cardiac disease, a mildly altered thyroid status was associated with increased risk of mortality that remains constant during all the follow-up.

Correlation of clinical changes with regard to thyroxine replacement therapy in hypothyroid patients: focusing on the change of renal function

Thyroid dysfunction has an important role in renal insufficiency. The aim of the study was to correlate the change of renal function with other clinical factors after thyroxine therapy in hypothyroid patients. A prospective study was designed and 30 hypothyroid patients were included. All study subjects received 0.15-0.2 mg/day thyroxine for 12 weeks. Diastolic blood pressure and serum levels of creatine phosphokinase (CPK) and myoglobulin decreased significantly after thyroxine therapy. Serum creatinine decreased (0.87 ± 0.22 vs. 0.70 ± 0.17 mg/dl, p < 0.001) and estimated glomerular filtration rate (eGFR) increased significantly (82.06 ± 31.08 vs. 100.31 ± 31.79 ml/min/1.73 m(2); p < 0.001) after thyroxine replacement. Left ventricular ejection fraction (LVEF) was significantly increased after thyroxine replacement (64.47 ± 11.94 vs. 72.40 ± 13.89%, p = 0.026). No significant vascular functional changes of peripheral (pulse wave velocity) and renal interlobar arteries (pulsatility index and resistance index) were noted. The change of eGFR significantly correlated with the changes of serum-free T(4) (fT(4)), CPK, myoglobulin and LVEF. The correlation between the change of eGFR and thyroid-stimulating hormone (TSH) level was not significant. In conclusion, the GFR of hypothyroid patients increased significantly after thyroxine replacement. The change of GFR was significantly correlated with the changes of fT(4), CPK, myoglobulin and LVEF, but not with TSH.