Thyroid-stimulating hormone and risk of sudden cardiac death, total mortality and cardiovascular morbidity

Thyroid dysfunction and mortality in cardiovascular hospitalized patients

Background

Thyroid dysfunction (TD) is associated with increased cardiovascular morbidity and mortality. Early detection may influence the clinical management.

Objective

To determine the prevalence, predictors, and prognostic value of TD among hospitalized cardiac patients.

Methods

A retrospective analysis of a 12-year database consisting of nonselectively adult patients admitted to a Cardiology Department and who were all screened for serum thyroid-stimulation-hormone (TSH) levels . Statistical analysis of demographic and clinical characteristics, mortality and length of hospital stay (LOS) was performed.

Results

A total of 14369 patients were included in the study; mean age was 67 years, 38.3% females. 1465 patients (10.2%) had TD. The most frequent type of TD was mildly elevated TSH (5.4%) followed by mildly reduced TSH (2.1%), markedly elevated TSH (1.5%), and markedly reduced TSH (1.2%). Female gender, history of hypothyroidism, heart failure, atrial fibrillation, renal failure and amiodarone use were significantly associated with TD. During follow-up 2975 (20.7%) patients died. There was increased mortality in the mildly reduced TSH subgroup (hazard ratio [HR] =1.44), markedly elevated TSH subgroup (HR=1.40) and mildly elevated TSH subgroup (HR=1.27). LOS was longer for patients with TD; the longest stay was observed in the markedly elevated TSH subgroup (odds ratio=1.69).

Conclusion

The prevalence of TD in hospitalized cardiac patients is 10.2%. TD is associated with an increased mortality rate and LOS. Consequently, routine screening for thyroid function in this population is advisable, particularly for selected high-risk subgroups. Future studies are needed to determine whether optimizing thyroid function can improve survival in these patients.

2024 Heart Disease and Stroke Statistics: A Report of US and Global Data From the American Heart Association

BACKGROUND

The American Heart Association (AHA), in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, nutrition, sleep, and obesity) and health factors (cholesterol, blood pressure, glucose control, and metabolic syndrome) that contribute to cardiovascular health. The AHA Heart Disease and Stroke Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, brain health, complications of pregnancy, kidney disease, congenital heart disease, rhythm disorders, sudden cardiac arrest, subclinical atherosclerosis, coronary heart disease, cardiomyopathy, heart failure, valvular disease, venous thromboembolism, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The AHA, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States and globally to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2024 AHA Statistical Update is the product of a full year's worth of effort in 2023 by dedicated volunteer clinicians and scientists, committed government professionals, and AHA staff members. The AHA strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional global data, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Systematic review and meta-analysis of levothyroxine effect on blood pressure in patients with subclinical hypothyroidism

This study aims to evaluate the effect of levothyroxine therapy on blood pressure (BP) in patients with subclinical hypothyroidism (SCH). Were searched Six databases, and randomized controlled trials (RCT) and prospective cohort studies evaluating the effect of levothyroxine therapy on BP in patients with SCH were included. 37 articles (9 RCTs and 28 prospective cohorts) were included in this meta-analysis. Pooled analysis of RCT studies was insignificant; however, pooled analysis of 28 prospective cohort studies showed a significant difference before and after the therapy, reducing both systolic blood pressure (SBP) and diastolic blood pressure (DBP) (MD=-4.02 [-6.45, -4.58] and MD=-2.13 [-3.69, -0.56], both P-values<0.05). Levothyroxine therapy can play a role in lowering BP in patients with SCH. However, this effect is more observed in Caucasians, SCH patients with higher initial TSH followed by more remarkable TSH change to normal levels, and SCH patients with hypertension.

Subclinical thyroid dysfunction and the risk of incident atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Thyroid hormones act on the cardiovascular system directly by modulating its function and indirectly by transcriptional regulation of gene expression in the heart and the vasculature. Studies have shown associations between overt and subclinical thyroid disorders and cardiovascular outcomes. The aim of this study was to perform a systematic review and meta-analysis to assess the potential relationships between subclinical hyper- and hypothyroidism and risk of atrial fibrillation (AF), and post-operative AF.

METHODS

MEDLINE and Scopus databases were searched from inception to 18th February 2023 for randomised controlled trials, case-control studies, and cohort studies which assessed the relationship between subclinical thyroid dysfunction and incident AF events. Risk of bias and the quality of evidence were assessed using the RoBANS tool and GRADE approach, respectively. Meta-analysis was conducted in Review Manager 5.4 using the Mantel-Haenszel statistical method and a random-effects model. Data are presented as risk ratios with 95% confidence intervals. Statistical heterogeneity amongst studies was assessed by the chi-squared (χ2) test and I2 statistic. p≤0.05 were considered significant.

RESULTS

A total of 6467 records were identified, of which 10 cohort studies met the inclusion criteria. Both subclinical hyperthyroidism and subclinical hypothyroidism were associated with an increased risk of incident AF (risk ratio (RR), 1.99; 95% confidence interval (CI), 1.43-2.77; n = 5 studies; p<0.0001 and RR, 1.19; CI, 1.03-1.39; n = 7 studies; p = 0.02, respectively). Subgroup analysis for post-operative AF revealed marked heterogeneity between studies (I2 = 84%) and association with subclinical hypothyroidism was not significant (RR, 1.41; CI, 0.89-2.22; n = 3 studies; p = 0.15).

CONCLUSIONS

The current evidence suggests that both subclinical hyperthyroidism and subclinical hypothyroidism are associated with increased risk of incident AF. Further investigation is required to determine potential causal links that would guide future clinical practice.

Plasma TSH and cardiovascular disease in the general population: A Mendelian randomization study of 105,224 individuals

BACKGROUND AND AIMS

The association between thyroid stimulating hormone (TSH) and cardiovascular disease has mainly been determined using clinical categories of disease. We tested the hypothesis that TSH on a continuous scale is associated with risk of atrial fibrillation (AF), myocardial infarction (MI), stroke, heart failure (HF), aortic valve stenosis (AVS), and major adverse cardiovascular events (MACE) and whether these associations are likely to be causal.

METHODS

We first tested whether plasma TSH on a continuous scale was observationally associated with incident cardiovascular events in a prospective cohort study of 105,224 individuals from the Copenhagen General Population Study followed for a median 7 years. Next, we tested whether a genetic risk score weighted on TSH was associated with cardiovascular endpoints. Finally, using Mendelian randomization, we tested whether the observed associations were likely to be causal.

RESULTS

Using restricted cubic splines, lower concentrations of TSH relative to the population median (=1.53 mIU/L) were associated with higher risk of AF, MI, stroke, HF, AVS, and MACE. Comparing individuals with TSH ≤5th percentile (≤0.54 mIU/L) versus >50th percentile (>1.53 mIU/L), hazard ratios (HRs) ranged from 1.12 (1.00-1.26) for stroke to 1.27 (1.11-1.46) for HF. Genetic risk estimates per standard deviation decrease in TSH were 1.28 (1.08-1.52) for AF, 1.35 (1.06-1.71) for MI, 1.06 (0.89-1.26) for stroke, 1.19 (0.94-1.52) for HF, 1.53 (1.03-2.26) for AVS, and 1.09 (0.97-1.23) for MACE.

CONCLUSIONS

In 105,224 individuals from the general population low plasma TSH was observationally and genetically associated with increased risk of AF, MI, and AVS suggesting that these observations may reflect causal pathways.

Thyroid-stimulating hormone within the normal reference range has a U-shaped association with the severity of coronary artery disease in nondiabetic patients but is diluted in diabetic patients

Too high or too low thyroid-stimulating hormone (TSH) has been associated with the progress and prognosis of coronary artery disease (CAD). However, whether TSH within its normal reference range plays a role in the severity of CAD remains unclear. In this observational study, we explored the potential relationship of hypersensitive TSH (hs-TSH) with the severity of CAD in euthyroid patients with or without diabetes mellitus. A total of 7357 CAD patients with euthyroidism were enrolled in this study. Of those, 1997 had diabetes mellitus. The severity of CAD was evaluated through the presence of myocardial infarction (MI) and the severity of coronary lesions, which was calculated using the Gensini score (GS). Logistic regression models treating hs-TSH as a categorical variable and restricted cubic spline analyses treating it as a continuous variable were used to evaluate the associations of hs-TSH with the severity of CAD. The propensity score matching method was used to further validate the differences between diabetic and nondiabetic patients. CAD patients with diabetes mellitus had lower levels of hs-TSH (1.6 (0.97-2.53) vs 1.67 (1.00-2.64)) in serum compared with CAD patients without diabetes mellitus. Meanwhile, hs-TSH was independently related to the severity of CAD. In CAD patients with vs without diabetes mellitus, the U-shaped relationship between hs-TSH and MI was more prominent in patients without diabetes mellitus, and the significant U-shaped association between higher GS and hs-TSH remained only in nondiabetes. Therefore, hs-TSH within the normal reference range has a U-shaped association with the severity of CAD in nondiabetic patients, which is markedly diluted in diabetic patients.

Heart Disease and Stroke Statistics-2023 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2023 Statistical Update is the product of a full year's worth of effort in 2022 by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. The American Heart Association strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional COVID-19 (coronavirus disease 2019) publications, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

The relationship between thyroid dysfunction, cardiovascular morbidity and mortality in type 2 diabetes: The Fremantle Diabetes Study Phase II

AIMS

It is uncertain whether subclinical thyroid dysfunction is associated with cardiovascular disease (CVD) events and mortality in people with type 2 diabetes. The aim of this study was to determine whether undetected thyroid disease increases the risk of incident CVD and death in type 2 diabetes.

METHODS

One thousand two hundred fifty participants with type 2 diabetes (mean age 65.3 years, 56.5% males, median diabetes duration 8.0 years) without known thyroid disease and not taking medications known to affect thyroid function were categorised, based on baseline serum free thyroxine (FT4) and thyrotropin (TSH) concentrations, as euthyroid, overt hypothyroid (increased TSH, low FT4), subclinical hypothyroid (increased TSH, normal FT4), overt thyrotoxic (decreased TSH, raised FT4) or subclinical thyrotoxic (decreased TSH, normal FT4). Incident myocardial infarction, incident stroke, all-cause and cardiovascular mortality were ascertained during a mean 6.2-6.7 years of follow-up.

RESULTS

Most participants with newly-detected thyroid dysfunction had subclinical hypothyroidism (77.2%) while overt/subclinical thyrotoxicosis was infrequent. Compared to participants with TSH 0.34-2.9 mU/L, those with TSH > 5.1 mU/L were not at increased risk of incident myocardial infarction (adjusted hazard ratio (95% confidence limits) 1.77 (0.71, 2.87)), incident stroke (1.66 (0.58, 4.78)), all-cause mortality (0.78 (0.44, 1.37)) or cardiovascular mortality (1.16 (0.38, 3.58)). Independent baseline associates of subclinical hypothyroidism included estimated glomerular filtration rate and systolic blood pressure.

CONCLUSIONS

Subclinical hypothyroidism was not independently associated with CVD events or mortality in community-dwelling people with type 2 diabetes despite its associations with CVD risk factors, questioning strategies to identify and/or treat mild thyroid dysfunction outside usual care.

Minor perturbations of thyroid homeostasis and major cardiovascular endpoints—Physiological mechanisms and clinical evidence

It is well established that thyroid dysfunction is linked to an increased risk of cardiovascular morbidity and mortality. The pleiotropic action of thyroid hormones strongly impacts the cardiovascular system and affects both the generation of the normal heart rhythm and arrhythmia. A meta-analysis of published evidence suggests a positive association of FT4 concentration with major adverse cardiovascular end points (MACE), but this association only partially extends to TSH. The risk for cardiovascular death is increased in both subclinical hypothyroidism and subclinical thyrotoxicosis. Several published studies found associations of TSH and FT4 concentrations, respectively, with major cardiovascular endpoints. Both reduced and elevated TSH concentrations predict the cardiovascular risk, and this association extends to TSH gradients within the reference range. Likewise, increased FT4 concentrations, but high-normal FT4 within its reference range as well, herald a poor outcome. These observations translate to a monotonic and sensitive effect of FT4 and a U-shaped relationship between TSH and cardiovascular risk. Up to now, the pathophysiological mechanism of this complex pattern of association is poorly understood. Integrating the available evidence suggests a dual etiology of elevated FT4 concentration, comprising both ensuing primary hypothyroidism and a raised set point of thyroid function, e. g. in the context of psychiatric disease, chronic stress and type 2 allostatic load. Addressing the association between thyroid homeostasis and cardiovascular diseases from a systems perspective could pave the way to new directions of research and a more personalized approach to the treatment of patients with cardiovascular risk.

Heart rate variability in hypothyroid patients: A systematic review and meta-analysis

Introduction

Hypothyroidism may be associated with changes in the autonomic regulation of the cardiovascular system, which may have clinical implications.

Objective

To conduct a systematic review and meta-analysis on the impact of hypothyroidism on HRV.

Materials and methods

PubMed, Cochrane, Embase and Google Scholar were searched until 20 August 2021 for articles reporting HRV parameters in untreated hypothyroidism and healthy controls. Random-effects meta-analysis were stratified by degree of hypothyroidism for each HRV parameters: RR intervals (or normal to normal-NN intervals), SDNN (standard deviation of RR intervals), RMSSD (square root of the mean difference of successive RR intervals), pNN50 (percentage of RR intervals with >50ms variation), total power (TP), LFnu (low-frequency normalized unit), HFnu (high-frequency), VLF (very low frequency), and LF/HF ratio.

Results

We included 17 studies with 11438 patients: 1163 hypothyroid patients and 10275 healthy controls. There was a decrease in SDNN (effect size = -1.27, 95% CI -1.72 to -0.83), RMSSD (-1.66, -2.32 to -1.00), pNN50 (-1.41, -1.98 to -0.84), TP (-1.55, -2.1 to -1.00), HFnu (-1.21, -1.78 to -0.63) with an increase in LFnu (1.14, 0.63 to 1.66) and LF/HF ratio (1.26, 0.71 to 1.81) (p <0.001). HRV alteration increased with severity of hypothyroidism.

Conclusions

Hypothyroidism is associated with a decreased HRV, that may be explained by molecular mechanisms involving catecholamines and by the effect of TSH on HRV. The increased sympathetic and decreased parasympathetic activity may have clinical implications.

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.

Heart Disease and Stroke Statistics-2022 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2022 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population and an enhanced focus on social determinants of health, adverse pregnancy outcomes, vascular contributions to brain health, and the global burden of cardiovascular disease and healthy life expectancy.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Clinical-epidemiological and radiological characteristics of stroke patients: A multicentre study

INTRODUCTION AND AIM

Stroke is the leading cause of disability in adults and the second most common cause of death, at a rate of 11.8% worldwide. The purpose of this study was to examine the aetiological, demographic, and clinical characteristics of patients admitted to hospital because of acute strokes.

MATERIALS AND METHODS

This multicentre study retrieved information for all patients admitted to hospital because of an acute cerebrovascular event over a six-month period, and sociodemographic, aetiological, and clinical characteristics were recorded.

RESULTS

A total of 1136 patients, 520 of whom were women (45.7%), with a mean age of 70.3 ± 12.8 years, were included in the study. Of these, 967 were diagnosed with ischaemic stroke (IS) (85.1%), 99 with haemorrhagic stroke (HS) (8.7%), and 70 with transient ischaemic attack (6.1%). The most common risk factor for stroke was hypertension (73%). Carotid disease and hyperlipidaemia rates were higher in patients with HS. Numbers of functionally dependent patients with severe neurological status according to the National Institutes of Health Stroke Scale and modified Rankin scale were significantly higher in the HS group (P < .001). When IS was classified according to the Trial of Org 10172 in Acute Stroke Treatment, small vessel disease emerged as the most common cause (41%). The most common lesion localisations were the parietal lobe (23%) in the IS group and the thalamus (35.3%) in the HS group. Eighty-eight patients (7.7%), 62 (6.4%) in the ischaemic subgroup, and 26 (26.3%) in the haemorrhagic subgroup, died within the first month.

CONCLUSION

Current and accurate evaluations of stroke aetiology are essential for stroke prevention and treatment planning. This study, shows that no change occurred in the aetiology of stroke and epidemiological characteristics and that accurate identification of modifiable stroke risk factors is still a major goal.

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.

A simple immunosensor for thyroid stimulating hormone

Determination of thyroid-stimulating hormone (TSH) level in serum or plasma is defined as a sensitive method for the diagnosis of hyperthyroidism and hypothyroidism and also in many diseases thought to be related to TSH levels. In this study, a novel simple impedimetric immunosensor based on polyamidoamine dendrimer was developed. Anti TSH antibody was immobilized on the gold electrode by using cysteamine self-assembled monolayer strategy. In constructing the immunosensor, a polyamidoamine dendrimer was used to increase the surface area in which Antı-TSH was immobilized and glutaraldehyde was used as a cross-linker. After each immobilization step, the electrode surface was monitored by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques and optimization studies were performed. The reproducibility, repeatability, linearity and sensitivity of the immunosensor were examined. Also, the interference experiments for glucose, salts and proteins in serum were performed. The limit of detection and limit of quantification values of the proposed immunosensor were 0.026 mIUL^-1 and 0.086 mIUL^-1, respectively and it was able to detect the amount of TSH within a linear range of 0.1-0.6 mIUL^-1.

Heart Disease and Stroke Statistics-2021 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2021 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, an enhanced focus on social determinants of health, adverse pregnancy outcomes, vascular contributions to brain health, the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors related to cardiovascular disease.

RESULTS

Each of the 27 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

The Association of Overt and Subclinical Hyperthyroidism with the Risk of Cardiovascular Events and Cardiovascular Mortality: Meta-Analysis and Systematic Review of Cohort Studies

BACKGROUND

Whether hyperthyroidism is an independent risk factor for cardiovascular events remains controversial. We aimed to evaluate the association of overt and subclinical hyperthyroidism with the risk of ischemic heart disease (IHD), stroke, heart failure, and cardiovascular mortality.

METHODS

Studies regarding the association between hyperthyroidism and cardiovascular events were searched on PubMed and Embase databases. The cardiovascular disease (CVD) risk was classified as high and low, based on pre-existing diseases, including history of coronary, cerebral, or peripheral artery disease; heart failure; atrial fibrillation; diabetes mellitus; or chronic kidney disease.

RESULTS

Thirty-seven cohort studies were included in this meta-analysis. The pooled hazard ratio for subjects with overt hyperthyroidism compared with the control group was 1.11 (95% confidence interval [CI], 1.03 to 1.19) for IHD, 1.35 (95% CI, 1.03 to 1.75) for stroke, and 1.20 (95% CI, 1.00 to 1.46) for cardiovascular mortality. For subjects with subclinical hyperthyroidism, the pooled hazard ratio was 1.24 (95% CI, 1.07 to 1.45) for IHD, when compared with the control group. Subgroup analysis by CVD risk showed that the risk of stroke in overt hyperthyroidism was increased in the low CVD risk group; however, these association was not observed in the high CVD risk group. Similarly, the risk of IHD in subjects with subclinical hyperthyroidism was significantly increased in the low CVD risk group.

CONCLUSION

Overt hyperthyroidism is associated with increased risk of IHD, stroke, and cardiovascular mortality, and subclinical hyperthyroidism is associated with increased risk of IHD. These associations were particularly observed in the low risk CVD group without underlying CVD.

The Two Faces of Janus: Why Thyrotropin as a Cardiovascular Risk Factor May Be an Ambiguous Target

Elevated concentrations of free thyroid hormones are established cardiovascular risk factors, but the association of thyrotropin (TSH) levels to hard endpoints is less clear. This may, at least in part, ensue from the fact that TSH secretion depends not only on the supply with thyroid hormones but on multiple confounders including genetic traits, medication and allostatic load. Especially psychosocial stress is a still underappreciated factor that is able to adjust the set point of thyroid function. In order to improve our understanding of thyroid allostasis, we undertook a systematic meta-analysis of published studies on thyroid function in post-traumatic stress disorder (PTSD). Studies were identified via MEDLINE/PubMed search and available references, and eligible were reports that included TSH or free thyroid hormone measurements in subjects with and without PTSD. Additionally, we re-analyzed data from the NHANES 2007/2008 cohort for a potential correlation of allostatic load and thyroid homeostasis. The available evidence from 13 included studies and 3386 euthyroid subjects supports a strong association of both PTSD and allostatic load to markers of thyroid function. Therefore, psychosocial stress may contribute to cardiovascular risk via an increased set point of thyroid homeostasis, so that TSH concentrations may be increased for reasons other than subclinical hypothyroidism. This provides a strong perspective for a previously understudied psychoendocrine axis, and future studies should address this connection by incorporating indices of allostatic load, peripheral thyroid hormones and calculated parameters of thyroid homeostasis.

The association of thyroid stimulation hormone levels with incident ischemic heart disease, incident stroke, and all-cause mortality

PURPOSE

Thyroid dysfunction may affect the risk of cardiovascular disease and mortality through effects on myocardial and vascular tissue and metabolism. Levels of thyroid stimulating hormone (TSH) indicates thyroid function. We aimed to assess the association between TSH-levels and incident ischemic heart disease (IHD), incident stroke, and all-cause mortality.

METHODS

We included 13,865 participants (18-71 years, 51.6% women) from five cohort studies conducted during 1974-2008 were included. TSH was measured at the baseline examination and classified as <0.4; 0.4-2.5 (ref.); 2.5-5.0; 5.0-10, or >10 mU/l. Incident IHD, incident stroke, and all-cause mortality were identified in registries until ultimo 2013. Data were analysed by multivariate Cox regression with age as underlying time axis. Results from the individual cohorts were pooled by random-effects meta-analysis.

RESULTS

The crude incidence rate was for IHD 7.8 cases/1000 person years (PY); stroke 5.4 cases/1000 PY; and all-cause mortality 11.3 deaths/1000 PY (mean follow-up: 14 years). Analyses showed no statistically significant associations between TSH-levels and incident IHD or incident stroke in the partly or fully adjusted models. There was a statistically significant association between TSH of 2.5-5 mU/l and all-cause mortality (hazard ratio 1.145 (95% CI 1.004-1.306) compared with TSH of 0.4-2.5 mU/l in the fully adjusted model.

CONCLUSION

The results do not provide evidence of a harmful effect of decreased or increased TSH on IHD or stroke in the general population. However, there is some indication of an elevated risk for all-cause mortality with TSH 2.5-5 mU/l compared with 0.4-2.5 mU/l.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Thyroid-stimulating hormone within the normal range and risk of major adverse cardiovascular events in nonischemic dilated cardiomyopathy patients with severe left ventricular dysfunction

BACKGROUND

The association between thyroid-stimulating-hormone (TSH) and prognosis of nonischemic dilated cardiomyopathy (NIDCM) in patients with normal thyroid function remains unclear.

HYPOTHESIS

Our aim was to investigate the association between TSH and major adverse cardiovascular events in euthyroid NIDCM patients.

METHODS

The original cohort consisted of 216 consecutive euthyroid NIDCM patients, with left ventricular ejection fraction (LVEF) ≤35%, who were observed from 2010 to 2013. Patients with persistent ventricular arrhythmia (VA) histories, amiodarone taken for VA prevention, or on heart transplant list within 1 year were excluded. A follow-up evaluation was performed, and VA events, heart failure (HF) exacerbation/heart transplant, cardiac death, or death from any cause were separately evaluated.

RESULTS

A total of 184 patients were enrolled, and 97.8% (180/184) ultimately received follow-up evaluations. During the median 4.6-year follow-up, 24 VA events, 28 cardiac deaths, 30 all-cause deaths, 40 HF exacerbations, and 11 heart transplant events occurred. Serum TSH levels showed good predictive efficacies for VA events (area under the curve [AUC] = 0.702, 95% confidence interval [CI]: 0.629-0.767), and the risk of VA events increased, according to serum TSH quarters, as determined by Kaplan-Meier analysis (2.2% vs 13.4% vs 21.0% vs 30.0%, Q1-Q4, P = 0.011). Multivariable Cox analysis showed that patients at the Q4 level of serum TSH (>2.67 mIU/L) suffered an increased risk of VA events, compared with those at the Q1 level of TSH (hazard ratio [HR] = 15.88, 95% CI: 2.01-65.15) or those at the other three quarters (HR = 3.17, 95% CI: 1.38-7.26). However, the Q4 TSH level was not associated with other adverse cardiac events.

CONCLUSION

An association between TSH levels and the risk of VA events may exist in euthyroid NIDCM patients.

Relationship between heart rate variability and subclinical thyroid disorders of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

The association between subclinical thyroid dysfunctions and autonomic modulation changes has been described by many studies with conflicting results. We aimed to analyze the association between subclinical hyperthyroidism (SCHyper), subclinical hypothyroidism (SCHypo), and heart rate variability (HRV) using the baseline from ELSA-Brasil. SCHyper and SCHypo were classified by use of medication to treat thyroid disorders, thyrotropin levels respectively above and under the reference range, and normal free thyroxine levels. For HRV, the participants underwent 10 min in supine position and the R-R intervals of the final 5 min were selected for analysis. We first used linear regression models to report crude data and then, multivariate adjustment for sociodemographic (age, sex, and race) and cardiovascular risk factors (hypertension, dyslipidemia, diabetes, smoking, body mass index, use of alcohol, and leisure physical activity) using the euthyroid group as reference. From 9270 subjects (median age, 50; interquartile range: 44–56), 8623 (93.0%) were classified as euthyroid, 136 (1.5%) as SCHyper, and 511 (5.5%) as SCHypo. Compared to euthyroid subjects, SCHyper participants presented significantly higher heart rate (68.8 vs 66.5 for euthyroidism, P=0.007) and shorter R-R intervals (871.4 vs 901.6, P=0.007). Although SCHyper was associated with lower standard deviation of NN interval (SDNN) (β: –0.070; 95% confidence interval (95%CI): –0.014 to –0.009) and low-frequency (LF) (β: –0.242, 95%CI: –0.426 to –0.058) compared to the euthyroid group, these differences lost significance after multivariate adjustment for confounders. No significant differences were found for HRV in SCHypo. No association was found between HRV and SCHyper or SCHypo compared to euthyroid subjects in this sample of apparently healthy subjects.

Effect of Levothyroxine on Blood Pressure in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-Analysis

Background: Patients with subclinical hypothyroidism (SCH) have elevated blood pressure, but the effect of levothyroxine (LT4) therapy on blood pressure among those patients is still unclear. This study aimed to assess whether LT4 therapy could reduce blood pressure in SCH patients through a systematic review and meta-analysis. Methods: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science were searched. Randomized controlled trials (RCTs) assessing the effect of LT4 therapy on blood pressure or prospective follow-up studies comparing the blood pressure level before and after LT4 treatment were included, and the mean difference of systolic blood pressure (SBP) or diastolic blood pressure (DBP) was pooled using random-effect meta-analysis. Results: Twenty-nine studies including 10 RCTs and 19 prospective follow-up studies were eligible for the analysis. Meta-analysis of 10 RCTs suggested that LT4 therapy could significantly reduce SBP in SCH patients by 2.48 mmHg (95% CI -4.63 to -0.33, P = 0.024). No heterogeneity was observed among these 10 RCTs (I² = 0%). Meta-analysis of the 19 prospective follow-up studies found that LT4 therapy significantly decreased SBP and DBP by 4.80 mmHg (95%CI -6.50 to -3.09, P < 0.001) and 2.74 mmHg (95%CI -4.06 to -1.43, P < 0.001), respectively. Conclusion: The findings suggest that LT4 replacement therapy can reduce blood pressure in SCH patients, which needs to be validated in more clinical trials with larger samples.