Thyroid replacement therapy and heart failure

Subclinical hypothyroidism predicts outcome in heart failure: insights from the T.O.S.CA. registry

Subclinical hypothyroidism (SH), defined as increased serum thyroid-stimulating hormone (TSH) with normal free T4 (fT4) levels, is frequently observed in the general population. Prevalence ranges from 0.6% to 1.8% in the adult population, depending on age, sex, and iodine intake. Several studies reported a worse prognosis in patients with heart failure with reduced ejection fraction (HFrEF) and SH, but they considered heterogeneous populations suffering mainly from severe SH. Aim of this study was to evaluate if SH was independently associated with the occurrence of cardiovascular death considering 30 months of follow-up. 277 HFrEF patients enrolled in the prospective, multicenter, observational T.O.S.CA. (Terapia Ormonale Scompenso CArdiaco) registry, were included in this analysis. Patients were divided into two groups according to the presence of SH (serum TSH levels > 4.5 mIU/L with normal fT4 levels). Data regarding clinical status, echocardiography, and survival were analyzed. Twenty-three patients displayed SH (87% mild vs 13% severe), while 254 were euthyroid. No differences were found in terms of age, sex, HF etiology, and left ventricular ejection fraction. When compared with the euthyroid group, SH patients showed higher TSH levels (7.7 ± 4.1 vs 1.6 ± 0.9, p < 0.001), as expected, with comparable levels of fT4 (1.3 ± 0.3 vs 1.3 ± 0.3, p = NS). When corrected for established predictors of poor outcome in HF, the presence of SH resulted to be an independent predictor of cardiovascular mortality (HR: 2.96; 5-95% CI:1.13-7.74; p = 0.03). Since thyroid tests are widely available and inexpensive, they should be performed in HF patients to detect subclinical disorders, evaluate replacement therapy, and improve prognosis.

Cardiac recovery from pressure overload is not altered by thyroid hormone status in old mice

Introduction

Thyroid hormones (THs) are known to have various effects on the cardiovascular system. However, the impact of TH levels on preexisting cardiac diseases is still unclear. Pressure overload due to arterial hypertension or aortic stenosis and aging are major risk factors for the development of structural and functional abnormalities and subsequent heart failure. Here, we assessed the sensitivity to altered TH levels in aged mice with maladaptive cardiac hypertrophy and cardiac dysfunction induced by transverse aortic constriction (TAC).

Methods

Mice at the age of 12 months underwent TAC and received T4 or anti-thyroid medication in drinking water over the course of 4 weeks after induction of left ventricular pressure overload.

Results

T4 excess or deprivation in older mice had no or only very little impact on cardiac function (fractional shortening), cardiac remodeling (cardiac wall thickness, heart weight, cardiomyocyte size, apoptosis, and interstitial fibrosis), and mortality. This is surprising because T4 excess or deprivation had significantly changed the outcome after TAC in young 8-week-old mice. Comparing the gene expression of deiodinases (Dio) 2 and 3 and TH receptor alpha (TRα) 1 and the dominant-negative acting isoform TRα2 between young and aged mice revealed that aged mice exhibited a higher expression of TRα2 and Dio3, while expression of Dio2 was reduced compared with young mice. These changes in Dio2 and 3 expressions might lead to reduced TH availability in the hearts of 12-month-old mice accompanied by reduced TRα action due to higher TRα2.

Discussion

In summary, our study shows that low and high TH availability have little impact on cardiac function and remodeling in older mice with preexisting pressure-induced cardiac damage. This observation seems to be the result of an altered expression of deiodinases and TRα isoforms, thus suggesting that even though cardiovascular risk is increasing with age, the response to TH stress may be dampened in certain conditions.

Natriuretic peptide testing strategies in heart failure: A 2023 update

Natriuretic peptides (NPs), including B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP), have been recommended as standard biomarkers for diagnosing heart failure (HF), and one of the strongest risk predictors for mortality and HF hospitalization regardless of ejection fraction (EF) and etiology of HF. BNP is an active neurohormone opposing renin-angiotensin-aldosterone and sympathetic nervous system overactivated in HF, whereas NT-proBNP is an inactive prohormone released from cardiomyocytes in response to wall stress. Despite substantial advances in the development of guideline-directed medical therapy (GDMT) for HF with reduced EF, studies demonstrating direct benefits of NP-guided chronic HF therapy on mortality, HF hospitalization, and GDMT optimization have yielded conflicting results. However, accumulating evidence shows that achieving prespecified BNP or NT-proBNP target over time is significantly associated with favorable outcomes, suggesting that benefits of serially measured NPs may be limited to particular groups of HF patients, such as those with extreme levels of baseline BNP or NT-proBNP, which could represent severe phenotypes of HF associated with natriuretic peptide resistance or cardiorenal syndrome. Over the past decade, clinical utilization of BNP and NT-proBNP has been expanded, especially using serial NP measurements for guiding HF therapy, optimizing GDMT and identifying at-risk patients with HF phenotypes who may be minimally symptomatic or asymptomatic.

Brain nuclear receptors and cardiovascular function

Brain-heart interaction has raised up increasing attentions. Nuclear receptors (NRs) are abundantly expressed in the brain, and emerging evidence indicates that a number of these brain NRs regulate multiple aspects of cardiovascular diseases (CVDs), including hypertension, heart failure, atherosclerosis, etc. In this review, we will elaborate recent findings that have established the physiological relevance of brain NRs in the context of cardiovascular function. In addition, we will discuss the currently available evidence regarding the distinct neuronal populations that respond to brain NRs in the cardiovascular control. These findings suggest connections between cardiac control and brain dynamics through NR signaling, which may lead to novel tools for the treatment of pathological changes in the CVDs.

Adverse effects of Lugol's iodine: Heart failure in a patient with subcutaneous phycomycosis from a resource-limited setting

Subcutaneous phycomycosis becomes a chronic, debilitating condition if left untreated. Treatment includes oral antifungal therapy, though oral potassium iodide has been used in resource-limited settings. Lugol's iodine has been an effective substitute, but little is known about its safety. We report a case of subcutaneous phycomycosis complicated by heart failure during treatment with Lugol's iodine. We review subcutaneous phycomycosis, iodine-mediated cardiotoxicity, as well as social determinants of health relevant to our case, suggesting that Lugol's iodine may only be an effective treatment with proper dosing and long-term monitoring.

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Lugol's iodine has been an alternative therapy in resource-limited settings.

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Proper dosing and long-term monitoring is essential to prevent toxicity.

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Excess iodine can cause heart failure through hyperthyroid and hypothyroid states.

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Social determinants of health may cause dosing errors and inadequate monitoring.

Cardioprotective doses of thyroid hormones improve NO bioavailability in erythrocytes and increase HIF-1α expression in the heart of infarcted rats

CONTEXT

Infarction leads to a decrease in NO bioavailability in the erythrocytes. Thyroid hormones (TH) present positive effects after infarction. However, there are no studies evaluating the effects of cardioprotective doses of TH in the erythrocytes after infarction.

OBJECTIVE

This study aimed to evaluate the effects of TH in NO bioavailability and oxidative stress parameters in the erythrocytes of infarcted rats.

MATERIAL AND METHODS

Wistar rats were allocated into the three groups: Sham-operated (SHAM), infarcted (AMI) and infarcted + TH (AMIT). AMIT rats received T4 and T3 for 12 days by gavage. Subsequently, the animals were evaluated by echocardiography and the LV and erythrocytes were collected.

RESULTS

TH improved NO bioavailability and increased catalase activity in the erythrocytes. Besides that, TH increased HIF-1α in the heart.

CONCLUSION

TH seems to be positive for erythrocytes preventing a decrease in NO bioavailability and increasing antioxidant enzymatic defense after infarction.

The effectiveness of thyroid hormone replacement therapy on heart failure and low T3-syndrome: An updated systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

The purpose of this study was to conduct a systematic review and meta-analysis evaluating the role of thyroid hormone therapy in patients with heart failure (HF) and low triiodothyronine (T3) syndrome (LT3S).

METHODS

The electronic databases PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database, Wanfang Database, and China Biology Medicine disc (CBMdisc) were systematically searched to identify eligible studies published before November 27, 2021. The mean difference was pooled for RCTs using a random-effects model.

RESULTS

The meta-analysis showed that thyroid hormone treatment improved the left ventricular ejection fraction (weighted mean difference [WMD] 5.61, 95% confidence interval [CI]: 4.38 to 6.85^, I² = 63.12%, P^<0.01). The cardiac output improved with thyroid hormone therapy (WMD 0.65, 95% CI: 0.42 to 0.89, I² = 84.28%, P^<0.01). The E/A in the thyroid hormone group was also improved compared to the control group (WMD 0.29, 95% CI: 0.15 to 0.42^, I² = 95.08%, P^<0.01). The left ventricular diastolic dysfunction was decreased with thyroid hormone treatment (WMD -5.17, 95% CI: -7.47 to -2.88, I² = 90.18%, P^<0.01). The brain natriuretic peptide decreased with thyroid hormone treatment (standardized mean difference [SMD] -1.49, 95% CI: -2.15 to -0.84, I² = 90.18%, P^<0.01). Noradrenaline decreased with thyroid hormone therapy (WMD -349.86, 95% CI: -401.05 to -298.67^, I² = 0%, P^<0.01). Free T3 increased with thyroid hormone treatment (SMD 2.18, 95% CI: 0.75 to 2.60^, I² = 98.20%, P^<0.01).

CONCLUSION

This meta-analysis showed that thyroid hormone replacement therapy was effective in patients with HF and LT3S.

Hypothyroidism and Risk of Cardiovascular Disease

Thyroid hormones (TH) have a significant impact on cellular oxidative metabolism. Besides that, they maintain vascular homeostasis by positive effects on endothelial and vascular smooth muscle cells. Subclinical (SCH) and clinical (CH) hypothyroidism influences target organs by changing their morphology and function and impaired blood and oxygen supply induced by accelerated atherosclerosis. The increased risk of acceleration and extension of atherosclerosis in patients with SCH and CH could be explained by dyslipidemia, diastolic hypertension, increased arterial stiffness, endothelial dysfunction, and altered blood coagulation. Instability of atherosclerotic plaque in hypothyroidism could cause excessive activity of the elements of innate immunity, which are characterized by: the significant presence of macrophages in atherosclerotic plaques, increased nuclear factor kappa B (NFkB) expression, and elevated levels of tumor necrosis factor α (TNF-α) and matrix metalloproteinase (MMP) 9, with reduced interstitial collagen, which all together creates inflammation milieu resulted in plaque rupture. Optimal substitution by levothyroxine (LT4) restores biochemical euthyroidism. In postmenopausal women and elderly patients with hypothyroidism and associated vascular comorbidity, excessive LT4 substitution could lead to atrial rhythm disorders and osteoporosis. Therefore, it is of interest to maintain thyroid-stimulating hormone (TSH) levels in the reference range, thus eliminating the deleterious effects of lower or higher TSH levels on the cardiovascular system. This review summarizes the recent literature on subclinical and clinical hypothyroidism and atherosclerotic cardiovascular disease and discusses the effects of LT4 replacement therapy on restoring biochemical euthyroidism and atherosclerosis processes.

Effects of thyroid dysfunction and thyroid stimulating hormone levels on the Atrial fibrillation risks: a systematic review and dose-response meta-analysis from cohort studies

OBJECTIVE

To explore the relationship between thyroid dysfunction, thyroid stimulating hormone (TSH) levels and risks of atrial fibrillation (AF) in studies as well as to conduct a dose-response meta-analysis on the correlation between TSH levels and AF risks.

METHODS

13 studies from five databases with 649,293 subjects (mean age 65.1 years) were included. The dose-response meta-analysis was conducted by comparing the Risk Ratios (RRs) and 95% Confidence Intervals (CI) for incident AF associated with different levels of TSH (vs TSH=0 mU/L) across studies. Data were collected until Oct 25, 2021.

RESULTS

Subclinical hyperthyroidism, subclinical hypothyroidism, clinical hyperthyroidism were associated with the increased risk of AF respectively (RR=1.70, 95% CI: 1.11-2.62; RR=1.23, 95% CI:1.05-1.44; RR=2.35, 95% CI:1.07-5.16), while clinical hypothyroidism was not found associated with the significantly increased risk of AF (RR=1.20, 95% CI: 0.72-1.99). A non-linear relationship was observed in two models (crude model: P_nonlinear<0.001; adjusted model: P_nonlinear =0.0391) between the TSH concentrations and the risks of AF.

CONCLUSIONS

Our study indicated that subclinical hyperthyroidism, subclinical hypothyroidism, clinical hyperthyroidism were associated with the risk of AF, and the results for TSH levels and AF risk were mixed which showed a U-shaped relationship.

Effect of hypothyroidism on contractile performance of isolated end-stage failing human myocardium

The relationship between hypothyroidism and the occurrence and progression of heart failure (HF) has had increased interest over the past years. The low T3 syndrome, a reduced T3 in the presence of normal thyroid stimulating hormone (TSH), and free T4 concentration, is a strong predictor of all-cause mortality in HF patients. Still, the impact of hypothyroidism on the contractile properties of failing human myocardium is unknown. Our study aimed to investigate that impact using ex-vivo assessment of force and kinetics of contraction/relaxation in left ventricular intact human myocardial muscle preparations. Trabeculae were dissected from non-failing (NF; n = 9), failing with no hypothyroidism (FNH; n = 9), and failing with hypothyroidism (FH; n = 9) hearts. Isolated muscle preparations were transferred into a custom-made setup where baseline conditions as well as the three main physiological modulators that regulate the contractile strength, length-dependent and frequency-dependent activation, as well as β-adrenergic stimulation, were assessed under near-physiological conditions. Hypothyroidism did not show any additional significant impact on the contractile properties different from the recognized alterations usually detected in such parameters in any end-stage failing heart without thyroid dysfunction. Clinical information for FH patients in our study revealed they were all receiving levothyroxine. Absence of any difference between failing hearts with or without hypothyroidism, may possibly be due to the profound effects of the advanced stage of heart failure that concealed any changes between the groups. Still, we cannot exclude the possibility of differences that may have been present at earlier stages. The effects of THs supplementation such as levothyroxine on contractile force and kinetic parameters of failing human myocardium require further investigation to explore its full potential in improving cardiovascular performance and cardiovascular outcomes of HF associated with hypothyroidism.

Decreased triiodothyronine (T3) as a predictor for prolonged mechanical ventilation in critically ill patients with cardiac surgery

BACKGROUND

This study aimed to examine the correlation between thyroid hormone and prolonged mechanical ventilation (MV) in adult critically ill patients having undergone cardiac surgery.

METHODS

The present study refers to a retrospective, cohort study conducted at Nanjing First Hospital from March 2019 to December 2020. Patients receiving cardiac surgery and admitting to the Cardiovascular Intensive Care Unit (CVICU) in the study period were screened for potential inclusion. Demographic information, thyroid hormone and other laboratory measurements and outcome variables were recorded for analysis. Prolonged MV was defined as the duration of MV after cardiac surgery longer than 5 days. Thyroid hormones were assessed for the prognostic significance for prolonged MV.

RESULTS

One thousand eight hundred ninety-six patients who underwent cardiac surgery were screened for potential enrollment. Overall, 118 patients were included and analyzed in this study. Patients fell to the control (n = 64) and the prolonged MV group (n = 54) by complying with the duration of MV after cardiac surgery. The median value of total triiodothyronine (TT3) and free triiodothyronine (FT3) were 1.03 nmol/L and 3.52 pmol/L in the prolonged MV group before cardiac surgery, significantly lower than 1.23 nmol/L (P = 0.005) and 3.87 pmol/L, respectively in control (P = 0.038). Multivariate logistic regression analysis indicated that TT3 before surgery (pre-op TT3) had an excellent prognostic significance for prolonged MV (OR: 0.049, P = 0.012).

CONCLUSIONS

This study concluded that decreased triiodothyronine (T3) could be common in cardiac patients with prolonged MV, and it would be further reduced after patients undergo cardiac surgery. Besides, decreased T3 before surgery could act as an effective predictor for prolonged MV after cardiac surgery.

Thyroid Status and Brain Circulation: The Rotterdam Study

CONTEXT

Whether thyroid dysfunction is related to altered brain circulation in the general population remains unknown.

OBJECTIVE

We determined the association of thyroid hormones with different markers of brain circulation within community-dwelling elderly people.

METHODS

This was a population-based study of 3 subcohorts of the Rotterdam Study, starting in 1989, 2000, and 2006. A total of 5142 participants (mean age, 63.8 years; 55.4% women), underwent venipuncture to measure serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4). Between 2005 and 2015, all participants underwent phase-contrast brain magnetic resonance imaging to assess global brain perfusion (mL of blood flow/100 mL of brain/minute). Arteriolar retinal calibers were assessed using digitized images of stereoscopic fundus color transparencies in 3105 participants as markers of microcirculation. We investigated associations of TSH, FT4 with brain circulation measures using (non)linear regression models.

RESULTS

FT4 (in pmol/L) levels had an inverse U-shaped association with global brain perfusion, such that high and low levels of FT4 were associated with lower global brain perfusion than middle levels of FT4. The difference in global brain perfusion between high FT4 levels (25 pmol/L) and middle FT4 levels (FT4 = 15 pmol/L; P nonlinearity = .002) was up to -2.44 mL (95% CI -4.31; -0.56). Higher and lower levels of FT4, compared with middle FT4 levels, were associated with arteriolar retinal vessels (mean difference up to -2.46 µm, 95% CI -4.98; 0.05 for lower FT4).

CONCLUSION

These results suggest that thyroid dysfunction could lead to brain diseases such as stroke or dementia through suboptimal brain circulation that is potentially modifiable.

Endocrine system dysfunction and chronic heart failure: a clinical perspective

Chronic heart failure (CHF) leads to an excess of urgent ambulatory visits, recurrent hospital admissions, morbidity, and mortality regardless of medical and non-medical management of the disease. This excess of risk may be attributable, at least in part, to comorbid conditions influencing the development and progression of CHF. In this perspective, the authors examined and described the most common endocrine disorders observed in patients with CHF, particularly in individuals with reduced ejection fraction, aiming to qualify the risks, quantify the epidemiological burden and discuss about the potential role of endocrine treatment. Thyroid dysfunction is commonly observed in patients with CHF, and sometimes it could be the consequence of certain medications (e.g., amiodarone). Male and female hypogonadism may also coexist in this clinical context, contributing to deteriorating the prognosis of these patients. Furthermore, growth hormone deficiency may affect the development of adult myocardium and predispose to CHF. Limited recommendation suggests to screen endocrine disorders in CHF patients, but it could be interesting to evaluate possible endocrine dysfunction in this setting, especially when a high suspicion coexists. Data referring to long-term safety and effectiveness of endocrine treatments in patients with CHF are limited, and their impact on several "hard" endpoints (such as hospital admission, all-cause, and cardiovascular mortality) are still poorly understood.

Incidence of Post-Heart Transplant Chronic Thyroiditis and Its Association With Pretransplant Amiodarone Use

BACKGROUND

Chronic thyroiditis (CT) is a common cause of thyroid dysfunction and could therefore adversely affect outcomes in patients undergoing heart transplant (HT). The incidence of post-HT CT and whether amiodarone, a commonly used anti-arrhythmic drug in patients with heart failure during pre-HT period, is associated with the development of post-HT CT are unknown.

METHODS

A retrospective review of HT recipients from February 2, 2010 to October 16, 2018 was performed. Patients who lacked relevant pre-/post-HT records, underwent thyroidectomy, had pre-HT thyroid dysfunction or thyroiditis within 15 days post-HT, and those on amiodarone during the post-HT period were excluded, yielding a final cohort of 75 patients.

RESULTS

Patients had a mean age of 63.3 ± 1.4 years and were predominantly male (90.7%) and white (80%). The incidence of post-HT CT was 32% with the majority (83.3%) manifesting as hypothyroidism. Median time to diagnosis of CT after transplant was 10.2 months (interquartile range, 4-27.4). Additionally, the CT group had higher pre-HT use of amiodarone (non-CT vs CT: 21.6% vs 50%, P = .01), higher prevalence of atrial fibrillation (non-CT vs CT: 23.5% vs 45.8%; P = .05), and more stage IV/V chronic kidney disease (non-CT vs CT: 2% vs 16.7%, P = .02). On multivariate analysis, pre-HT amiodarone use was associated with the development of post-HT CT after adjustment for age, sex, and chronic kidney disease (odds ratio, 3.65; 95% CI, 1.17-11.44; P = .03).

CONCLUSION

The incidence of post-HT CT is high and is strongly associated with pre-HT amiodarone use underpinning the importance of closely following the post-HT thyroid profile in these patients.

Thyroid Hormone Plays an Important Role in Cardiac Function: From Bench to Bedside

Thyroid hormones (THs) are synthesized in the thyroid gland, and they circulate in the blood to regulate cells, tissues, and organs in the body. In particular, they exert several effects on the cardiovascular system. It is well known that THs raise the heart rate and cardiac contractility, improve the systolic and diastolic function of the heart, and decrease systemic vascular resistance. In the past 30 years, some researchers have studied the molecular pathways that mediate the role of TH in the cardiovascular system, to better understand its mechanisms of action. Two types of mechanisms, which are genomic and non-genomic pathways, underlie the effects of THs on cardiomyocytes. In this review, we summarize the current knowledge of the action of THs in the cardiac function, the clinical manifestation and parameters of their hemodynamics, and treatment principles for patients with hyperthyroid- or hypothyroid-associated heart disease. We also describe the cardiovascular drugs that induce thyroid dysfunction and explain the mechanism underlying the thyroid toxicity of amiodarone, which is considered the most effective antiarrhythmic agent. Finally, we discuss the recent reports on the involvement of thyroid hormones in the regulation of myocardial regeneration and metabolism in the adult heart.

Protective Effects of Thyroid Hormone Deprivation on Progression of Maladaptive Cardiac Hypertrophy and Heart Failure

Purpose: Thyroid hormones (TH) play a central role for cardiac function. TH influence heart rate and cardiac contractility, and altered thyroid function is associated with increased cardiovascular morbidity and mortality. The precise role of TH in onset and progression of heart failure still requires clarification. Methods: Chronic left ventricular pressure overload was induced in mouse hearts by transverse aortic constriction (TAC). One week after TAC, alteration of TH status was induced and the impact on cardiac disease progression was studied longitudinally over 4 weeks in mice with hypo- or hyperthyroidism and was compared to euthyroid TAC controls. Serial assessment was performed for heart function (2D M-mode echocardiography), heart morphology (weight, fibrosis, and cardiomyocyte cross-sectional area), and molecular changes in heart tissues (TH target gene expression, apoptosis, and mTOR activation) at 2 and 4 weeks. Results: In diseased heart, subsequent TH restriction stopped progression of maladaptive cardiac hypertrophy and improved cardiac function. In contrast and compared to euthyroid TAC controls, increased TH availability after TAC propelled maladaptive cardiac growth and development of heart failure. This was accompanied by a rise in cardiomyocyte apoptosis and mTOR pathway activation. Conclusion: This study shows, for the first time, a protective effect of TH deprivation against progression of pathological cardiac hypertrophy and development of congestive heart failure in mice with left ventricular pressure overload. Whether this also applies to the human situation needs to be determined in clinical studies and would infer a critical re-thinking of management of TH status in patients with hypertensive heart disease.

T3 as predictor of mortality in any cause non-critically ill patients

BACKGROUND

Low T3 syndrome refers to a set of thyroid hormone metabolism alterations present in the disease state. A correlation between low T3 and poor clinical outcomes in the intensive care unit is more established. Nonetheless, studies on non-critically ill patients are few and controversial.

OBJECTIVE

To evaluate the prevalence and predictive value of low T3 levels on 30-day and 6-month mortality in non-critically ill patients. Secondary outcomes evaluated the length of hospital stay, overall mortality, and hospital readmission.

DESIGN

Prospective cohort study.

METHODS

A total of 345 consecutive patients from the Internal Medicine ward of a tertiary hospital in southern Brazil were included and followed from October 2018 to April 2019 (6 months). Levels of total serum T3 were measured weekly, from admission to discharge, and correlated with 30-day and 6-month mortality.

RESULTS

Prevalence of low T3 was 36.6%. Low T3 levels were associated with higher 30-day hospital mortality (15.1% vs 4.1%, P < 0.001) and higher 6-month overall mortality (31.7% vs 13.2%, P < 0.001). Total serum T3 at admission was an independent predictor of 30-day hospital mortality.

CONCLUSION

Low T3 levels are a prevalent condition among non-critically ill patients, and this condition is associated with poor clinical outcomes in this population. Total serum T3 levels, alone or in association with other predictive scores, were demonstrated to be an easy and valuable tool for risk stratification and should be further employed in this setting.

The Role of Thyroid Hormone in Neuronal Protection

Thyroid hormone is essential for brain development and brain function in the adult. During development, thyroid hormone acts in a spatial and temporal-specific manner to regulate the expression of genes essential for normal neural cell differentiation, migration, and myelination. In the adult brain, thyroid hormone is important for maintaining normal brain function. Thyroid hormone excess, hyperthyroidism, and thyroid hormone deficiency, hypothyroidism, are associated with disordered brain function, including depression, memory loss, impaired cognitive function, irritability, and anxiety. Adequate thyroid hormone levels are required for normal brain function. Thyroid hormone acts through a cascade of signaling components: activation and inactivation by deiodinase enzymes, thyroid hormone membrane transporters, and nuclear thyroid hormone receptors. Additionally, the hypothalamic-pituitary-thyroid axis, with negative feedback of thyroid hormone on thyrotropin-releasing hormone (TRH) and thyroid-stimulating hormone (TSH) secretion, regulates serum thyroid hormone levels in a narrow range. Animal and human studies have shown both systemic and local reduction in thyroid hormone availability in neurologic disease and after brain trauma. Treatment with thyroid hormone and selective thyroid hormone analogs has resulted in a reduction in injury and improved recovery. This article will describe the thyroid hormone signal transduction pathway in the brain and the role of thyroid hormone in the aging brain, neurologic diseases, and the protective role when administered after traumatic brain injury. © 2021 American Physiological Society. Compr Physiol 11:1-21, 2021.

Lower levels of triiodothyronine are associated with poor hemodynamic profile and all-cause mortality in heart failure

Background: We aimed to assess the association of triiodothyronine (T3) hormone with invasive hemodynamic parameters and all-cause mortality in heart failure with reduced ejection fraction (HFrEF). Results: About 483 HFrEF patients were enrolled. Patients with the lowest T3 tertile had advanced New York Heart Association (NYHA) classes, had higher uric acid, brain natriuretic peptide. T3 level had a positive correlation with cardiac index (CI) and a negative correlation with pulmonary vascular resistance and pulmonary capillary wedge pressure. Adjusted with NYHA III-IV classes, uric acid, aspartate aminotransferase and CI, T3 level was found to be an independent predictor of all-cause mortality. In Kaplan-Meier analysis, the lowest T3 tertile had the lowest survival function. Conclusion: Free T3 is positively correlated with CI and negatively correlated with pulmonary vascular resistance and pulmonary capillary wedge pressure in patients with HFrEF. Lower levels of T3 seems to be a poor prognostic factor in this particular patient population.

Prognostic value of free triiodothyronine and N-terminal pro-B-type natriuretic peptide for patients with acute myocardial infarction undergoing percutaneous coronary intervention: a prospective cohort study

Background

Altered thyroid function and increased N-terminal pro-B-type natriuretic peptide (NT-proBNP) are prognostic factors in acute myocardial infarction (AMI). The study aims to investigate whether free triiodothyronine (fT3) and NT-proBNP are prognostic factors for long-term outcomes in patients with AMI undergoing percutaneous coronary intervention (PCI).

Methods

This was an observational, prospective, single-center study of consecutive patients enrolled at Fuwai Hospital between January, 2013 and December, 2013. The patients were divided into two groups according to fT3 levels: low fT3 (<2.5 pg/mL) and normal fT3 (2.50–4.09 pg/mL). The primary outcome of this study was the incidence of major adverse cardiovascular events (MACEs).

Results

There were 252 patients with low fT3 and 561 patients with normal fT3. After >2 years of follow-up, patients with low fT3 levels had higher rates of MACEs than those with normal fT3 (27.0% vs. 7.8%, P<0.001). Univariable Cox proportional hazards regression analyses showed that NT-proBNP >802.7 pg/mL [hazard ratio (HR) =5.063, 95% confidence interval (CI): 3.176–8.071, P<0.001] and fT3 <2.5 pg/mL (HR =3.867, 95% CI: 2.646–5.651, P<0.001) were the strongest predictors of MACEs. After adjustment for traditional risk predictors, fT3 <2.5 pg/mL (HR =2.570, 95% CI: 1.653–3.993, P<0.001) was one of the most important independent predictors of MACEs. Patients with NT-proBNP ≤802.7 pg/mL and fT3 ≥2.5 pg/mL had the best prognosis, while patients with NT-proBNP >802.7 pg/mL and fT3 <2.5 pg/mL had the worst outcomes (P<0.001).

Conclusions

Low fT3 is a strong predictor of poor prognosis after AMI. The fT3+NT-proBNP combination might be a valuable predictor of the long-term outcomes of PCI after AMI.

Association Between Low T3 Syndrome and Poor Prognosis in Adult Patients With Acute Myocarditis

BACKGROUND

This study aims to investigate the role of free triiodothyronine (fT3) in predicting poor prognosis of adult patients with acute myocarditis.

METHODS

A total of 173 consecutive adult patients with acute myocarditis completed thyroid function evaluations. They were divided into two groups according to fT3 levels: low fT3 group (n = 54, fT3 < 3.54 pmol/liter) and normal fT3 group (n = 119, fT3 ≥ 3.54 pmol/liter). The primary endpoint was major adverse cardiac events (MACE).

RESULTS

During the 3.5 ± 2.8 years follow-up, the rate of MACE was 29.6% versus 3.5% in low fT3 group versus normal fT3 group, respectively (P < 0.0001). Long-term at 8 years MACE-free survival were lower in low fT3 group versus normal fT3 group (52.9% versus 92.3%, log-rank P < 0.0001), respectively. Univariate Cox analysis showed that left ventricular ejection fraction (LVEF) < 50% [hazard ratio (HR) 10.231, 95% confidence interval (CI): 3.418-30.624, P < 0.0001) and low fT3 level (HR 0.360, 95% CI: 0.223-0.582, P < 0.0001) were strongest two predictors of MACE. After adjustment for traditional risk predictors, the prognostic value of fT3 status was still significant (HR 0.540, 95% CI: 0.316-0.922, P = 0.024). Compared with normal fT3 group, those in low fT3 group were at a much higher risk of MACE (HR 5.074, 95% CI: 1.518-16.964, P = 0.008).

CONCLUSIONS

Low T3 syndrome was a strong predictor of poor prognosis in adult patients with acute myocarditis. These findings suggest that fT3 level could serve as a biomarker for risk stratification in acute myocarditis patients.

T3 Critically Affects the Mhrt/Brg1 Axis to Regulate the Cardiac MHC Switch: Role of an Epigenetic Cross-Talk

The LncRNA my-heart (Mhrt) and the chromatin remodeler Brg1 inhibit each other to respectively prevent or favor the maladaptive α-myosin-heavy-chain (Myh6) to β-myosin-heavy-chain (Myh7) switch, so their balance crucially guides the outcome of cardiac remodeling under stress conditions. Even though triiodothyronine (T3) has long been recognized as a critical regulator of the cardiac Myh isoform composition, its role as a modulator of the Mhrt/Brg1 axis is still unexplored. Here the effect of T3 on the Mhrt/Brg1 regulatory circuit has been analyzed in relation with chromatin remodeling and previously identified T3-dependent miRNAs. The expression levels of Mhrt, Brg1 and Myh6/Myh7 have been assessed in rat models of hyperthyroidism or acute myocardial ischemia/reperfusion (IR) treated with T3 replacement therapy. To gain mechanistic insights, in silico analyses and site-directed mutagenesis have been adopted in combination with gene reporter assays and loss or gain of function strategies in cultured cardiomyocytes. Our results indicate a pivotal role of Mhrt over-expression in the T3-dependent regulation of Myh switch. Mechanistically, T3 activates the Mhrt promoter at two putative thyroid hormone responsive elements (TRE) located in a crucial region that is necessary for both Mhrt activation and Brg1-dependent Mhrt repression. This newly identified T3 mode of action requires DNA chromatinization and is critically involved in mitigating the repressive function of the Brg1 protein on Mhrt promoter. In addition, T3 is also able to prevent the Brg1 over-expression observed in the post-IR setting through a pathway that might entail the T3-mediated up-regulation of miR-208a. Taken together, our data evidence a novel T3-responsive network of cross-talking epigenetic factors that dictates the cardiac Myh composition and could be of great translational relevance.

[Use of thyroid hormones in the treatment of cardiovascular diseases: literature review]

Cardiovascular diseases remain the leading cause of death all over the world. Thyroid hormones play a significant role in the regulation of cardiac function. According to a number of researches, patients with cardiovascular diseases usually have a decrease in the concentration of thyroid hormones in the blood serum, which may be associated with a poor prognosis. Today it still remains unclear whether the change in the bioavailability of thyroid hormones in the myocardium is a favorable physiological mechanism or a replication of an adaptation disorder. Experimental researches suggest that thyroid hormone therapy may be applied in clinical cardiology. This review describes the results of researches examining the use of thyroid hormones in patients with cardiovascular diseases, as well as experiment data on animal models. The available data on the use of thyroid hormones in patients with acute myocardial infarction and heart failure allow us to suggest that normalization of thyroid hormone levels is a safe and potentially effective treatment method in the group of patients with cardiovascular disease. At the same time, the data on the use of thyroid hormones in patients who have undergone an open-heart surgery or heart transplantation are limited. However, at present, it is difficult to draw unambiguous conclusions about the benefits, as well as about the possible risk of using thyroid hormones in the described conditions. Large-scale clinical researches are required to confirm the safety and evaluate the effectiveness of such therapy. Moreover, it is necessary to set parameters for evaluating the safety and effectiveness and understand which hormone (thyroxine or triiodothyronine), what dosage and at what stage of the disease should be applied. Until we do not have answers for these questions, thyroid hormone therapy in patients with cardiovascular diseases should remain within the research field.

Relationship of thyroid dysfunction with cardiovascular diseases: updated review on heart failure progression

Heart disease remains the leading cause of death globally. Heart failure (HF) is a clinical syndrome that results from impairment of the ability of the ventricle to fill with or eject blood. Over the past two decades, accumulated evidence has revealed the contribution of thyroid hormones to cardiovascular (CV) events, exerting their action through genomic and non-genomic pathways within the cardiomyocytes. The pivotal role of thyroid hormones in maintaining cardiac homeostasis has been observed in previous investigations which suggest that the CV system is adversely impacted by fluctuations in thyroid hormone levels, such as those that occur in hypothyroidism, hyperthyroidism, and low triiodothyronine syndrome (LT₃S). Thyroid dysfunction has direct effects on myocardial contractility, systolic and diastolic blood pressure, heart mass, heart rate, ejection fraction, and heart output, which may ultimately lead to HF. Recent clinical data have shown that thyroid hormone replacement therapy for hypothyroid patients appears to provide the potential for reducing CV events. Therefore, this review aims to address the impact of thyroid hormone dysfunction on pathophysiological mechanisms contributing to the development and progression of HF.

Core functional nodes and sex-specific pathways in human ischaemic and dilated cardiomyopathy

Poor access to human left ventricular myocardium is a significant limitation in the study of heart failure (HF). Here, we utilise a carefully procured large human heart biobank of cryopreserved left ventricular myocardium to obtain direct molecular insights into ischaemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM), the most common causes of HF worldwide. We perform unbiased, deep proteomic and metabolomic analyses of 51 left ventricular (LV) samples from 44 cryopreserved human ICM and DCM hearts, compared to age-, gender-, and BMI-matched, histopathologically normal, donor controls. We report a dramatic reduction in serum amyloid A1 protein in ICM hearts, perturbed thyroid hormone signalling pathways and significant reductions in oxidoreductase co-factor riboflavin-5-monophosphate and glycolytic intermediate fructose-6-phosphate in both; unveil gender-specific changes in HF, including nitric oxide-related arginine metabolism, mitochondrial substrates, and X chromosome-linked protein and metabolite changes; and provide an interactive online application as a publicly-available resource.

The potential of the novel NAD+ supplementing agent, SNH6, as a therapeutic strategy for the treatment of Friedreich's ataxia

Friedreich's ataxia (FA) is due to deficiency of the mitochondrial protein, frataxin, which results in multiple pathologies including a deadly, hypertrophic cardiomyopathy. Frataxin loss leads to deleterious accumulations of redox-active, mitochondrial iron, and suppressed mitochondrial bioenergetics. Hence, there is an urgent need to develop innovative pharmaceuticals. Herein, the activity of the novel compound, 6-methoxy-2-salicylaldehyde nicotinoyl hydrazone (SNH6), was assessed in vivo using the well-characterized muscle creatine kinase (MCK) conditional frataxin knockout (KO) mouse model of FA. The design of SNH6 incorporated a dual-mechanism mediating: (1) NAD+-supplementation to restore cardiac bioenergetics; and (2) iron chelation to remove toxic mitochondrial iron. In these studies, MCK wild-type (WT) and KO mice were treated for 4-weeks from the asymptomatic age of 4.5-weeks to 8.5-weeks of age, where the mouse displays an overt cardiomyopathy. SNH6-treatment significantly elevated NAD+ and markedly increased NAD+ consumption in WT and KO hearts. In SNH6-treated KO mice, nuclear Sirt1 activity was also significantly increased together with the NAD+-metabolic product, nicotinamide (NAM). Therefore, NAD+-supplementation by SNH6 aided mitochondrial function and cardiac bioenergetics. SNH6 also chelated iron in cultured cardiac cells and also removed iron-loading in vivo from the MCK KO heart. Despite its dual beneficial properties of supplementing NAD+ and chelating iron, SNH6 did not mitigate cardiomyopathy development in the MCK KO mouse. Collectively, SNH6 is an innovative therapeutic with marked pharmacological efficacy, which successfully enhanced cardiac NAD+ and nuclear Sirt1 activity and reduced cardiac iron-loading in MCK KO mice. No other pharmaceutical yet designed exhibits both these effective pharmacological properties.

Regulation of nitric oxide production in hypothyroidism

Hypothyroidism is a common endocrine disorder that predominantly occurs in females. It is associated with an increased risk of cardiovascular diseases (CVD), but the molecular mechanism is not known. Disturbance in lipid metabolism, the regulation of oxidative stress, and inflammation characterize the progression of subclinical hypothyroidism. The initiation and progression of endothelial dysfunction also exhibit these changes, which is the initial step in developing CVD. Animal and human studies highlight the critical role of nitric oxide (NO) as a reliable biomarker for cardiovascular risk in subclinical and clinical hypothyroidism. In this review, we summarize the recent literature findings associated with NO production by the thyroid hormones in both physiological and pathophysiological conditions. We also discuss the levothyroxine treatment effect on serum NO levels in hypothyroid patients.

Comparison of Levothyroxine Dosing in Patients with and without Heart Failure

Background: Evidence has shown that low thyroid hormone levels may lead to worse prognosis including a higher mortality rate in patients with heart failure (HF). Thyroid replacement increases cardiac output and exercise performance without causing significant adverse events. The purpose of this study is to compare levothyroxine doses in patients with and without HF.Methods: This single center, retrospective cohort study compared levothyroxine doses in ambulatory hypothyroid patients with a history of HF to those without a history of HF. Patients were stratified into three groups: no HF, HF with reduced ejection fraction (HFrEF, EF<40%), and other types of HF. The primary endpoint of average levothyroxine dose was analyzed using multivariable linear regression with variables determined a priori.Results: Three hundred patients were included in the study with 100 patients in each arm. Average levothyroxine doses (mcg/kg) were 1.5 ± 0.7, 1.6 ± 0.8, and 1.6 ± 0.9 for no HF, other types of HF, HFrEF, respectively (p= .61). Factors found to be significantly related to levothyroxine dosing included gender, drug-drug interactions, and the timing of clinic visit to lab draw. No differences were found in secondary outcomes including TSH levels, free T₄, T₃, and percentage of patients with elevated thyroid-stimulating hormone (TSH) among HFrEF, other types of HF, and no HF patients. Among HF patients, average ejection fractions were also similar comparing patients with elevated TSH, normal TSH, and low TSH.Conclusion: The dose of levothyroxine was not significantly different in HF patients compared to patients without HF.

Hypothyroidism and Heart Failure: Epidemiology, Pathogenetic Mechanisms & Therapeutic Rationale

Heart Failure (HF) is a major public health problem and a major cause of morbidity and mortality worldwide. Thyroid hormones (TH) have multiple effects on the heart and cardiovascular system. In recent years, studies have shown that hypothyroidism, including subclinical hypothyroidism, is associated with an increased risk for developing and worsening of HF. This review addresses the relationship between HF and hypothyroidism by highlighting the epidemiology, pathophysiology and management.

Metabolic Dysfunction in Continuous-Flow Left Ventricular Assist Devices Patients and Outcomes

Background

Metabolic impairment is common in heart failure patients. Continuous‐flow left ventricular assist devices (CF‐LVADs) improve hemodynamics and outcomes in patients with advanced heart failure; however, the effect of CF‐LVADs on metabolic status is unknown. This study aims to evaluate the changes in metabolic status following CF‐LVAD implantation and measure the correlation of metabolic status with outcomes.

Methods and Results

Prospective data on CF‐LVAD patients were obtained. Metabolic evaluation, including hemoglobin A1C, free and total testosterone, thyroid‐stimulating hormone (TSH), and free T4, was obtained before and at multiple time points following implantation. Patients with nonelevated thyroid‐stimulating hormone and normal hemoglobin A1C and testosterone levels were defined as having normal metabolic status. Baseline characteristics, hemodynamics, and outcomes were collected. One hundred six patients were studied, of which 56 had paired data at baseline and 1‐ to 3‐month follow‐up. Before implantation, 75% of patients had insulin resistance, 86% of men and 39% of women had low free testosterone, and 44% of patients had abnormal thyroid function. There was a significant improvement in hemoglobin A1C, free testosterone, and thyroid‐stimulating hormone following implantation (P<0.001 for all). Patients with normal hemoglobin A1C (<5.7%) following implantation had higher 1‐year survival free of heart failure readmissions (78% versus 23%; P<0.001). Patients with normal metabolic status following implantation also had higher 1‐year survival free of heart failure readmissions (92% versus 54%; P=0.04).

Conclusions

Metabolic dysfunction is highly prevalent in advanced heart failure patients and improves after CF‐LVAD implantation. Normal metabolic status is associated with a significantly higher rate of 1‐year survival free of heart failure readmissions.

Multimorbidity and the Risk of All-Cause 30-Day Readmission in the Setting of Multidisciplinary Management of Chronic Heart Failure: A Retrospective Analysis of 830 Hospitalized Patients in Australia

BACKGROUND

Multimorbidity has an adverse effect on health outcomes in hospitalized individuals with chronic heart failure (CHF), but the modulating effect of multidisciplinary management is unknown.

OBJECTIVE

The aim of this study was to test the hypothesis that increasing morbidity would independently predict an increasing risk of 30-day readmission despite multidisciplinary management of CHF.

METHODS

We studied patients hospitalized for any reason with heart failure receiving nurse-led, postdischarge multidisciplinary management. We profiled a matrix of expected comorbidities involving the most common coexisting conditions associated with CHF and examined the relationship between multimorbidity and 30-day all-cause readmission.

RESULTS

A total of 830 patients (mean age 73 ± 13 years and 65% men) were assessed. Multimorbidity was common, with an average of 6.6 ± 2.4 comorbid conditions with sex-based differences in prevalence of 4 of 10 conditions. Within 30 days of initial hospitalization, 216 of 830 (26%) patients were readmitted for any reason. Greater multimorbidity was associated with increasing readmission (4%-44% for those with 0-1 to 8-9 morbid conditions; adjusted odds ratio, 1.25; 95% confidence interval, 1.13-1.38) for each additional condition. Three distinct classes of patient emerged: class 1-diabetes, metabolic, and mood disorders; class 2-renal impairment; and class 3-low with relatively fewer comorbid conditions. Classes 1 and 2 had higher 30-day readmission than class 3 did (adjusted P < .01 for both comparisons).

CONCLUSIONS

These data affirm that multimorbidity is common in adult CHF inpatients and in potentially distinct patterns linked to outcome. Overall, greater multimorbidity is associated with a higher risk of 30-day all-cause readmission despite high-quality multidisciplinary management. More innovative approaches to target-specific clusters of multimorbidity are required to improve health outcomes in affected individuals.

Risk factors for chronic thromboembolic pulmonary hypertension - Importance of thyroid disease and function

INTRODUCTION

Although a number of risk factors for chronic thromboembolic pulmonary hypertension (CTEPH) have been reported, the exact prevalence is controversial and varies between published cohorts. The aim of the present study was to investigate the prevalence of risk factors in operable CTEPH patients with special emphasis on thyroid disease and function.

MATERIAL AND METHODS

Overall, 228 CTEPH patients (47.7% female; median age 63 [IQR 52-72] years) scheduled for pulmonary endarterectomy between 01/2014 and 12/2015 were studied. Prevalence of risk factors was assessed, and patients were classified according to their thyroid function based on laboratory measurements.

RESULTS

As many as 86.0% of patients reported a history of pulmonary embolism (PE; of those, 24.5% were diagnosed with "acute" PE less than six months before the diagnosis of CTEPH), 80.7% of patients had a blood group non-0 and 24.1% of patients had known thyroid disease (of those, 78.2% hypothyroidism). Laboratory measurements revealed thyroid dysfunction in 10.5% of patients (of those, 54.8% had no known thyroid disease). Patients with hypothyroid function had higher WHO functional classes, NT-proBNP levels and a lower cardiac index compared to patients with euthyroid function.

CONCLUSIONS

The prevalence of a history of PE and blood group non-0 was higher than previously reported. However, a relevant proportion of patients might have suffered from pre-existing CTEPH rather than acute PE. Thyroid disease and dysfunction were frequent and hypothyroid function associated with more severe disease.

Serum nitric oxide levels correlate with quality of life questionnaires scores of hypothyroid females

Primary hypothyroidism can affect lipid metabolism, cardiovascular (CV) function, and overall patients' quality of life (QoL). Decrease in serum nitric oxide (NO) levels could promote the atherosclerosis acceleration in hypothyroid patients. Our hypothesis is that serum NO level is altered in hypothyroidism; more specifically, we hypothesize that the early vascular changes that can be observed in hypothyroidism could be due to these alterations and that serum NO levels are associated with lipid levels in female patients diagnosed with subclinical hypothyroidism (SCH) or clinical hypothyroidism (CH). Furthermore, since serum NO level is an early marker of atherosclerosis and related CV disorders, which are commonly present and follow hypothyreosis and greatly contribute to overall QoL, we further hypothesized that NO level would correlate with Thyroid Symptom Questionnaire (TSQ) and General Health Questionnaire 12 (GHQ12) scores in hypothyroid patients. A collaterally of our hypothesis was that levothyroxine (LT4) treatment would affect serum NO levels as well as TSQ and GHQ12 scores. Therefore, we have analyzed lipid profile, the level of NO and QoL scores in female patients diagnosed with SCH and CH in order to determine the correlation between NO and generic and thyroid disease symptoms in treatment naïve SCH and CH patients and after LT4 treatment and laboratory euthyroidism achievement. As a consequence of our hypothesis is that measurement of serum NO level in SCH and CH patients may be an innovative way to improve LT4 treatment efficacy. This assumption could have a practical significance for future investigations regarding the management of hypothyroidism treatment protocols in current guidelines.

Iodide Improves Outcome After Acute Myocardial Infarction in Rats and Pigs

OBJECTIVES

In this study, we tested whether iodide would reduce heart damage in rat and pig models of acute myocardial infarction as a risk analysis for a human trial.

DESIGN

Prospective blinded and randomized laboratory animal investigation.

SETTING

Animal research laboratories.

SUBJECTS

Sexually mature rats and pigs.

INTERVENTIONS

Acute myocardial infarction was induced by temporary ligation of the coronary artery followed by reperfusion. Iodide was administered orally in rats or IV in rats and pigs just prior to reperfusion.

MEASUREMENTS AND MAIN RESULTS

Damage was assessed by blood cardiac troponin and infarct size; heart function was determined by echocardiography. Blood peroxide scavenging activity was measured enzymatically, and blood thyroid hormone was determined using radioimmune assay. Iodide administration preserved heart function and reduced blood cardiac troponin and infarct size by approximately 45% in pigs and approximately 60% in rats. Iodide administration also increased blood peroxide scavenging activity and maintained thyroid hormone levels.

CONCLUSIONS

Iodide administration improved the structure and function of the heart after acute myocardial infarction in rats and pigs.

Thyroid Dysfunction in Heart Failure and Cardiovascular Outcomes

BACKGROUND

The effects of thyroid dysfunction in patients with preexisting heart failure have not been adequately studied. We examined the prevalence of thyroid dysfunction and associations with cardiovascular outcomes in a large, prospective cohort of outpatients with preexisting heart failure.

METHODS AND RESULTS

We examined associations between thyroid dysfunction and New York Heart Association class, atrial fibrillation, and a composite end point of ventricular assist device placement, heart transplantation, or death in 1365 participants with heart failure enrolled in the Penn Heart Failure Study. Mean age was 57 years, 35% were women, and the majority had New York Heart Association class II (45%) or III (32%) symptoms. More severe heart failure was associated with higher thyroid-stimulating hormone (TSH), higher free thyroxine (FT4), and lower total triiodothyronine (TT3) concentrations ( P<0.001 all models). Atrial fibrillation was positively associated with higher levels of FT4 alone ( P≤0.01 all models). There were 462 composite end points over a median 4.2 years of follow-up. In adjusted models, compared with euthyroidism, subclinical hypothyroidism (TSH 4.51-19.99 mIU/L with normal FT4) was associated with an increased risk of the composite end point overall (hazard ratio, 1.82; 95% CI, 1.27-2.61; P=0.001) and in the subgroup with TSH ≥7.00 mIU/L (hazard ratio, 3.25; 95% CI, 1.96-5.39; P<0.001), but not in the subgroup with TSH 4.51-6.99 mIU/L (hazard ratio, 1.26; 95% CI, 0.78-2.06; P=0.34). Isolated low T3 was also associated with the composite end point (hazard ratio, 2.12; 95% CI, 1.65-2.72; P<0.001).

CONCLUSIONS

In patients with preexisting heart failure, subclinical hypothyroidism with TSH ≥7 mIU/L and isolated low T3 levels are associated with poor prognosis. Clinical trials are needed to explore therapeutic effects of T4 and T3 administration in heart failure.

Triiodothyronine Reduces Vascular Dysfunction Associated with Hypertension by Attenuating Protein Kinase G/Vasodilator-Stimulated Phosphoprotein Signaling

Vascular dysfunction associated with hypertension comprises hypercontractility and impaired vasodilation. We have previously demonstrated that triiodothyronine (T3), the active form of thyroid hormone, has vasodilatory effects acting through rapid onset mechanisms. In the present study, we examined whether T3 mitigates vascular dysfunction associated with hypertension. To test the direct effects of T3 in hypertensive vessels, aortas from female Dahl salt-sensitive (Dahl SS) rats fed a high-salt diet (8% NaCl, HS group) and their age-matched controls fed a standard low-salt diet (0.3% NaCl, LS group) for 16 weeks were isolated and used in ex vivo vascular reactivity studies. We confirmed that the HS group exhibited a higher systolic blood pressure in comparison with the control LS group and displayed aortic remodeling. Aortas from both groups were pretreated with T3 (0.1 μM) for 30 minutes at 37°C in a 5% CO₂ incubator before functional vascular studies. T3 treatment significantly attenuated hypercontractility and improved impaired endothelium-dependent vasodilation in aortas from the HS group. These vascular improvements in response to T3 were accompanied by increased phosphorylation of vasodilator-stimulated phosphoprotein (VASP) at serine 239, a vasodilatory factor of the cGMP-dependent protein kinase (PKG)/VASP signaling pathway in vascular smooth muscle cells. Moreover, increased production of reactive oxygen species in aortas from the HS group were significantly reduced by T3, suggesting a potential antioxidant effect of T3 in the vasculature. These results demonstrate that T3 can mitigate hypertension-related vascular dysfunction through the VASP signaling pathway and by reducing vascular ROS production. SIGNIFICANCE STATEMENT: This study demonstrates that triiodothyronine (T3) directly acts on vascular tone and has a beneficial effect in hypertension-induced vascular dysfunction. T3 augmented vasodilation and diminished vasoconstriction in blood vessels from hypertensive rats in association with activation of the protein kinase G/vasodilator-stimulated phosphoprotein signaling pathway that activates vascular relaxation and exerted an antioxidant effect. Collectively, these results show that T3 is a potential vasoprotective agent with rapid action on hypertension-related vascular dysfunction.

Cardiogenic Shock Requiring Extracorporeal Membrane Oxygenation Support in a Patient with Panhypopituitarism: A Case Report

We present a 58-year-old female with a past history of a pituitary adenoma resected two years prior to admission who developed polymorphic ventricular tachycardia and cardiogenic shock requiring veno-arterial extracorporeal membrane oxygenation (VA-ECMO). We noted that the patient had stopped taking all of her medications six months prior to presentation. An extensive workup revealed acute panhypopituitarism with secondary hypothyroidism, secondary adrenal insufficiency, and central diabetes insipidus. She was immediately initiated on thyroid and adrenal hormone replacement therapy as well as fluid replacement. Within five days of her medical treatment, the patient's cardiac function improved and she was successfully weaned from VA-ECMO and subsequently discharged home with appropriate hormone replacement therapy.

Long-Term Outcome in Patients With Heart Failure Treated With Levothyroxine: An Observational Nationwide Cohort Study

CONTEXT

Hypothyroidism has detrimental effects on the cardiovascular system, but controversy remains concerning the benefits of levothyroxine (L-T4) substitution in patients with heart failure (HF).

OBJECTIVE

Examining the effects of L-T4 in patients with HF.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

All Danish citizens aged ≥18 years diagnosed with HF between 1997 and 2012. L-T4 treatment was identified from nationwide registers. Incidence rate ratios (IRRs) were calculated with Poisson regression models.

MAIN OUTCOME MEASURES

All-cause mortality, myocardial infarction (MI), cardiovascular death, and major adverse cardiovascular events (MACEs).

RESULTS

A total of 224,670 patients were diagnosed with HF [mean age 70.7 (SD ± 14.7) years, 53% male]. Of these, 6560 patients were treated with L-T4 at baseline, and 9007 patients initiated L-T4 during follow-up. A total of 209,103 patients did not receive L-T4. During a median follow-up of 4.8 years [interquartile range (IQR) 9.2] 147,253 patients died. Increased risk of all-cause mortality (IRR 1.25; 95% CI, 1.21 to 1.29; IRR 1.13; 95% CI, 1.10 to 1.16), cardiovascular death (IRR 1.23; 95% CI, 1.18 to 1.27; IRR 1.11; 95% CI, 1.08 to 1.15), and MACE (IRR 1.26; 95% CI, 1.22 to 1.31; IRR 1.05; 95% CI, 1.02 to 1.09) was observed for treatment ongoing at baseline and initiated during follow-up, respectively. Increased risk of MI (IRR 1.32; 95% CI, 1.23 to 1.41) was observed for ongoing treatment, and reduced risk (IRR 0.87; 95% CI, 0.81 to 0.93) was observed for incident treatment.

CONCLUSION

Ongoing and incident L-T4 treatment in patients with HF was associated with an increased risk of all-cause mortality, cardiovascular death, and MACE. Increased risk of MI was observed for ongoing treatment, and reduced risk was observed for incident treatment.

The impact of thyroid hormone dysfunction on ischemic heart disease

Thyroid hormones have a central role in cardiovascular homeostasis. In myocardium, these hormones stimulate both diastolic myocardial relaxation and systolic myocardial contraction, have a pro-angiogenic effect and an important role in extracellular matrix maintenance. Thyroid hormones modulate cardiac mitochondrial function. Dysfunction of thyroid axis impairs myocardial bioenergetic status. Both overt and subclinical hypothyroidism are associated with a higher incidence of coronary events and an increased risk of heart failure progression. Endothelial function is also impaired in hypothyroid state, with decreased nitric oxide-mediated vascular relaxation. In heart disease, particularly in ischemic heart disease, abnormalities in thyroid hormone levels are common and are an important factor to be considered. In fact, low thyroid hormone levels should be interpreted as a cardiovascular risk factor. Regarding ischemic heart disease, during the late post-myocardial infarction period, thyroid hormones modulate left ventricular structure, function and geometry. Dysfunction of thyroid axis might even be more prevalent in the referred condition since there is an upregulation of type 3 deiodinase in myocardium, producing a state of local cardiac hypothyroidism. In this focused review, we summarize the central pathophysiological and clinical links between altered thyroid function and ischemic heart disease. Finally, we highlight the potential benefits of thyroid hormone supplementation as a therapeutic target in ischemic heart disease.

The Management of Thyroid Abnormalities in Chronic Heart Failure

The cardiovascular system is one of the main targets of thyroid hormone action, and triiodothyronine deficiency has crucial consequences on cardiac structure and function. Patients with overt or subclinical hypothyroidism should be treated with levothyroxine to improve their cardiovascular function and the potential risk of heart failure. Even patients with thyroid hormone deficiency and heart failure should receive replacement doses of levothyroxine to improve their prognosis and worsening of the cardiovascular function. An innovative therapeutic multifactorial approach could improve the progression of heart failure. There is a potential beneficial effect of thyroid hormones and their analogs in patients with heart failure.

Usefulness of Triiodothyronine Replacement Therapy in Patients With ST Elevation Myocardial Infarction and Borderline/Reduced Triiodothyronine Levels (from the THIRST Study)

The aim of the study was to investigate whether TH replacement therapy is safe and impact infarct size, left ventricular (LV) volumes and function in patients with acute myocardial infarction (AMI) and low T3 syndrome (LT3S). Thirty-seven AMI/LT3S patients were randomly treated or untreated with liothyronine (T3) therapy (maximum dosage 15 mcg/m²/die) in addition to standardized treatment (T3-treated group, n = 19; untreated group, n = 18). TH and thyroxine (TSH) during hospital stay and at 1-month and 6 months were evaluated. At discharge and at 6 months LV volumes, ejection fraction, wall motion score index (WMSI) and infarct extent were measured by cardiac MR. T3-treated patients had a significant increase in fT3 (p = 0.003 and p <0.001) at discharge and 1-month. These patients had no signs or symptoms of hyperthyroidism or arrhythmias. At follow-up, there was a significant reduction in WMSI in both groups (T3-treated group: Δ = -0.12, p = 0.001; untreated group: Δ = -0.04, p = 0.04) and the difference value (discharge/follow-up) was significantly higher in T3-treated group than in untreated group (mean difference between groups = 0.08, 95% confidence interval [CI]: 0.01 to 0.15, p = 0.05). Also, stroke volume increased significantly in the T3-treated group (Δ = 3.4, 95% CI: 0.8 to 6, p <0.01) at follow-up. In conclusion, this is the first pilot experience in which T3 replacement therapy resulted safe and able to improve regional dysfunction in patients with STEMI/LT3S.

The combination of nonthyroidal illness syndrome and renal dysfunction further increases mortality risk in patients with acute myocardial infarction: a prospective cohort study

Background

Both nonthyroidal illness syndrome and renal dysfunction are associated with increased mortality risk in acute myocardial infarction (AMI). However, it is unclear whether combined NTIS and renal dysfunction further increase mortality risk. Therefore, our aim is to investigate whether combined NTIS and renal dysfunction further increases mortality risk in patients with acute myocardial infarction (AMI).

Methods

A total of 1295 inpatients with AMI were divided into normal group (n = 692), NTIS group (n = 139), renal dysfunction group (n = 304), and combined NTIS and renal dysfunction group (n = 160). Heart function, in-hospital, all-cause and cardiovascular mortality were compared among the four groups.

Results

After adjustment for age and sex, left ventricular ejection fraction was significantly lower in the combined group (48 ± 11%) than in the NTIS group (52 ± 10%, P = 0.017), the renal dysfunction group (52 ± 10%, P = 0.001) and the normal group (56 ± 8%, P < 0.001). After controlling for confounding factors, compared with the normal group, the NTIS and the renal dysfunction group represented higher risks of in-hospital mortality (OR: 3.643, P = 0.028; OR:3.135, P = 0.042, respectively), all-cause mortality (HR: 2.138, P = 0.007; HR: 2.050, P = 0.003, respectively), and cardiovascular mortality (HR:2.134, P = 0.042; HR:2.237, P = 0.010, respectively). Compared to those in the NTIS and the renal dysfunction group, the patients in the combined group showed a further increased risk for in-hospital mortality (OR:2.916, P = 0.039; OR:2.487, P = 0.036, respectively), all-cause mortality (HR: 1.939, P = 0.015; HR: 2.020, P = 0.002, respectively) and cardiovascular mortality (HR:2.420, P = 0.010; HR:2.303, P = 0.002, respectively).

Conclusions

Both NTIS and renal dysfunction increase short-term in-hospital mortality, and long-term all-cause and cardiovascular mortality risk in patients with AMI. Furthermore, the coexistence of NTIS and renal dysfunction presents further increased mortality risk in AMI patients.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1027-1) contains supplementary material, which is available to authorized users.

Efficacy and safety of levothyroxine (L-T4) replacement on the exercise capability in chronic systolic heart failure patients with subclinical hypothyroidism: Study protocol for a multi-center, open label, randomized, parallel group trial (ThyroHeart-CHF)

Background

Subclinical hypothyroidism is a common condition in patients with heart failure and is defined as elevated serum thyroid hormone (TSH) with normal circulating free thyroxine (FT4). Evidence on the effect of thyroid hormone treatment is lacking. We designed a randomized controlled trial to compare the efficacy and safety of thyroid hormone supplementation in patients with chronic heart failure complicated with subclinical hypothyroidism.

Methods/design

Eligible participants were identified from the cardiology units of five study centers based on the following criteria: 18 years or older, systolic heart failure with NewYork Heart Association (NYHA) class II–III, left ventricular ejection fraction ≤ 40%, and subclinical hypothyroidism (TSH > 4.78μIU/ml, < 10 μIU/ml + FT4 level within reference range). Eligible patients will be randomly assigned in a 1:1 manner to receive thyroxine replacement therapy plus standard chronic heart failure (CHF) treatment or only standard CHF therapy. Levothyroxine will be administered at an initial dose of 12.5 μg once daily and will be titrated until TSH is within the normal range. The primary endpoints include the difference in distance of the six-minute walk test between 24 weeks and baseline. The secondary endpoints include differences in plasma NT-proBNP levels and serum lipid profiles, changes in the NYHA classification, cardiovascular death, re-hospitalization, differences in echocardiographic and cardiac magnetic resonance imaging measures, and Minnesota Living With Heart Failure Questionnaire (MLHFQ) results between 24 weeks and baseline.

Discussion

ThyroHeart-CHF is designed as a prospective, multi-center, randomized, controlled clinical trial to study the efficacy and safety of thyroid hormone supplementation in patients with chronic heart failure complicated with subclinical hypothyroidism. The study findings will have significant implications for discovering the new therapeutic targets and methods of heart failure.

Trail Registration

ClinicalTrials.gov, NCT03096613. Registered on 30 March 2017.

Stage-dependent cardiac regeneration in Xenopus is regulated by thyroid hormone availability

Despite therapeutic advances, heart failure is the major cause of morbidity and mortality worldwide, but why cardiac regenerative capacity is lost in adult humans remains an enigma. Cardiac regenerative capacity widely varies across vertebrates. Zebrafish and newt hearts regenerate throughout life. In mice, this ability is lost in the first postnatal week, a period physiologically similar to thyroid hormone (TH)-regulated metamorphosis in anuran amphibians. We thus assessed heart regeneration in Xenopus laevis before, during, and after TH-dependent metamorphosis. We found that tadpoles display efficient cardiac regeneration, but this capacity is abrogated during the metamorphic larval-to-adult switch. Therefore, we examined the consequence of TH excess and deprivation on the efficiently regenerating tadpole heart. We found that either acute TH treatment or blocking TH production before resection significantly but differentially altered gene expression and kinetics of extracellular matrix components deposition, and negatively impacted myocardial wall closure, both resulting in an impeded regenerative process. However, neither treatment significantly influenced DNA synthesis or mitosis in cardiac tissue after amputation. Overall, our data highlight an unexplored role of TH availability in modulating the cardiac regenerative outcome, and present X. laevis as an alternative model to decipher the developmental switches underlying stage-dependent constraint on cardiac regeneration.

Novel Insight Into the Epigenetic and Post-transcriptional Control of Cardiac Gene Expression by Thyroid Hormone

Thyroid hormone (TH) signaling is critically involved in the regulation of cardiovascular physiology. Even mild reductions of myocardial TH levels, as occur in hypothyroidism or low T3 state conditions, are thought to play a role in the progression of cardiac disorders. Due to recent advances in molecular mechanisms underlying TH action, it is now accepted that TH-dependent modulation of gene expression is achieved at multiple transcriptional and post-transcriptional levels and involves the cooperation of many processes. Among them, the epigenetic remodeling of chromatin structure and the interplay with non-coding RNA have emerged as novel TH-dependent pathways that add further degrees of complexity and broaden the network of genes controlled by TH signaling. Increasing experimental and clinical findings indicate that aberrant function of these regulatory mechanisms promotes the evolution of cardiac disorders such as post-ischemic injury, pathological hypertrophy, and heart failure, which may be reversed by the correction of the underlying TH dyshomeostasis. To encourage the clinical implementation of a TH replacement strategy in cardiac disease, here we discuss the crucial effect of epigenetic modifications and control of non-coding RNA in TH-dependent regulation of biological processes relevant for cardiac disease evolution.

Heart Failure

Heart failure affects more than 6 million people in the United States and incurs a heavy toll in morbidity, mortality, and health care costs. It frequently coexists with other important disorders, including hypertension, coronary artery disease, diabetes, and obesity. Decades of clinical trials have shown that several medications and interventions are effective for improving outcomes; however, mortality and hospitalization rates remain high. More recently, additional medications and devices have shown promise in reducing the health burden of heart failure.