Native Magnetic Resonance T1-Mapping Identifies Diffuse Myocardial Injury in Hypothyroidism

Changes of cardiac function: cardiac adaptation in patients with hypothyroidism assessed by cardiac magnetic resonance-a meta-analysis

Objective

The meta-analysis aimed to explore the cardiac adaptation in hypothyroidism patients by cardiac magnetic resonance.

Research methods and procedures

Databases including PubMed, Cochrane Library, Embase, CNKI, and Sinomed for clinical studies of hypothyroidism on cardiac function changes. Databases were searched from the earliest data to 15 June 2023. Two authors retrieved studies and evaluated their quality. Review Manager 5.4.1 and Stata18 were used to analyze the data. This study is registered with the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY), 202440114.

Results

Six studies were selected for further analysis. Five of them reported differences in cardiac function measures between patients with hypothyroidism and healthy controls, and three studies reported cardiac function parameters after treatment in patients with hypothyroidism. The fixed-effect model combined WMD values for left ventricular ejection fraction (LVEF) had a pooled effect size of -1.98 (95% CI -3.50 to -0.44], P=0.01), implying that LVEF was lower in patients with hypothyroidism than in healthy people. Analysis of heterogeneity found moderate heterogeneity (P = 0.08, I² = 50%). WMD values for stroke volume (SV), cardiac index (CI), left ventricular end-diastolic volume index(LVEDVI), left ventricular end-systolic volume (LESVI), and left ventricular mass index(LVMI) were also analyzed, and pooled effect sizes showed the CI and LVEDVI of patients with hypothyroidism ware significantly decrease (WMD=-0.47, 95% CI [-0.93 to -0.00], P=0.05, WMD=-7.99, 95%CI [-14.01 to -1.96], P=0.009, respectively). Patients with hypothyroidism tended to recover cardiac function after treatment [LVEF (WMD = 6.37, 95%CI [2.05, 10.69], P=0.004), SV (WMD = 7.67, 95%CI [1.61, 13.74], P=0.01), CI (WMD = 0.40, 95%CI [0.01, 0.79], P=0.05)], and there was no difference from the healthy controls.

Conclusion

Hypothyroidism could affect cardiac function, although this does not cause significant heart failure. It may be an adaptation of the heart to the hypothyroid state. There was a risk that this adaptation may turn into myocardial damage. Cardiac function could be restored after treatment in patients with hypothyroidism. Aggressive levothyroxine replacement therapy should be used to reverse cardiac function.

Systematic review registration

https://inplasy.com, identifier (INPLASY202440114).

Epidemiology, Types, Causes, Clinical Presentation, Diagnosis, and Treatment of Hypothyroidism

Hypothyroidism means an underactive thyroid gland. This leads to a decrease in the functioning of the thyroid gland. It is a very common endocrine disorder that causes under-secretion of thyroid hormones, mainly thyroxine (T4) and triiodothyronine (T3). It affects people of every age group but is more commonly found in women and older people. The symptoms of hypothyroidism can go unnoticed, may not be specific, and may overlap with other conditions, which makes it harder to diagnose it in some cases. Common symptoms include fatigue, weight gain, increased sensitivity to cold (cold intolerance), irregular bowel movements (constipation), and dry skin (xeroderma). These conditions are mostly the result of a low metabolic rate in the body. Weight gain occurs due to a decrease in fat-burning rate and cold intolerance due to a decrease in heat production by the body. This condition can be caused by a variety of factors, including autoimmune diseases, radiation therapy, thyroid gland removal surgeries, and certain medications. The diagnosis of hypothyroidism is based on laboratory tests that measure the levels of thyroid hormones (T3 and T4) in the blood. Treatment typically involves lifelong hormone replacement therapy with synthetic thyroid hormone replacement medication, such as levothyroxine, to help regulate hormone levels in the body. People with hypothyroidism may need to have their medication dosage adjusted over time. If hypothyroidism is left untreated, it can lead to severe complications like mental retardation, delayed milestones, etc., in infants and heart failure, infertility, myxedema coma, etc., in adults. With appropriate treatment, the symptoms of hypothyroidism can be effectively managed, and most people with the condition can lead normal, healthy lives. Lifestyle modifications like eating healthy food and exercising regularly can help manage the symptoms and improve the quality of life.

Hypothyroidism: The difficulty in attributing symptoms to their underlying cause

Common symptoms of overt hypothyroidism are non-specific and include fatigue, lethargy, and dry skin. Although the diagnosis is considered to be straightforward, no single symptom can be used to identify patients with overt hypothyroidism, while many patients with subclinical hypothyroidism are asymptomatic. A large population-based study on the spectrum of symptoms in subclinical hypothyroidism showed similar rates of thyroid disease-related symptoms compared with euthyroid subjects, while the TSH concentration had no impact on symptom score. Together, these findings make it challenging to attribute symptoms to their underlying cause. This is also true in the case of unexplained persistent symptoms in levothyroxine-treated patients. Although generally considered a life-long replacement therapy, successful thyroid hormone discontinuation resulting in euthyroidism has been reported in approximately one third of patients. Thus, we overtreat patients with (subclinical) hypothyroidism, highlighting the importance of reliable diagnostic criteria. The diagnostic process, including the implementation of robust TSH and FT4 reference intervals, is especially challenging in specific situations including aging, pregnancy, non-thyroidal illness, and central hypothyroidism. There is a clear need for improved adherence to current guidelines from scientific societies and for willingness to manage symptoms without a clear pathological correlate, especially in the case of mild TSH elevations. This review will highlight recent literature on this topic and offers some practice points.

Myocardial oedema: pathophysiological basis and implications for the failing heart

Myocardial fluid homeostasis relies on a complex interplay between microvascular filtration, interstitial hydration, cardiomyocyte water uptake and lymphatic removal. Dysregulation of one or more of these mechanisms may result in myocardial oedema. Interstitial and intracellular fluid accumulation disrupts myocardial architecture, intercellular communication, and metabolic pathways, decreasing contractility and increasing myocardial stiffness. The widespread use of cardiac magnetic resonance enabled the identification of myocardial oedema as a clinically relevant imaging finding with prognostic implications in several types of heart failure. Furthermore, growing experimental evidence has contributed to a better understanding of the physical and molecular interactions in the microvascular barrier, myocardial interstitium and lymphatics and how they might be disrupted in heart failure. In this review, we summarize current knowledge on the factors controlling myocardial water balance in the healthy and failing heart and pinpoint the new potential therapeutic avenues.

Hypothyroidism is prevalent among adult women with chronic lower urinary tract symptoms

OBJECTIVE

To define the prevalence of hypothyroidism in women with chronic lower urinary tract symptoms (LUTS) and to compare the severity of each symptom between patients with hypothyroidism and controls.

SUBJECTS AND METHODS

In this prospective observational study, we screened all adult women who came to the urology clinic between March 2017 and September 2020, and enrolled patients with chronic LUTS in the study. We assessed thyroid function. We evaluated the severity of voiding and storage urinary symptoms by the International Prostate Symptom Score. We also assessed the severity of urge urinary incontinence (UUI) and stress urinary incontinence (SUI). For between-group analysis, we selected age-matched cases and controls and compared them regarding the distribution and severity of urinary symptoms.

RESULTS

Seven hundred and twenty-five women with a mean age of 51.7 ± 14.0 years were included in the final analysis. Two hundred fifty-eight patients (35.6%) had hypothyroidism. Age-matched case and control groups consisting of 210 patients each were selected. There was no significant difference in the severity and distribution of voiding LUTS and UUI between the study groups (P values >0.05). The severity of storage symptoms was lower in patients with hypothyroidism (P = 0.04). Sixty-seven patients with hypothyroidism (31.9%) had SUI, which was significantly higher than controls (23.3%) (P = 0.03).

CONCLUSION

More than one-third of women with chronic LUTS have hypothyroidism which is much more frequent than in the general population. We also suggest a possible relationship between hypothyroidism and the severity of SUI and an inverse relationship between hypothyroidism and storage symptoms.

Magnetic resonance T1-mapping quantitatively assesses the severity of thyroid destruction in patients with autoimmune thyroiditis

OBJECTIVE

Autoimmune thyroiditis (AIT) is a common organ-specific autoimmune disease. Longitudinal relaxation time mapping (T1-mapping) analyzed by magnetic resonance imaging is a new method for evaluating inflammation or fibrosis. This study aimed to investigate the relationship between thyroid T1-mapping value and degree of intrathyroidal inflammation and destruction in euthyroid AIT patients.

METHODS

This case-control study recruited 28 drug-naïve AIT patients and 18 healthy controls. Thyroid specimens were collected for assessing the mRNA expression of inflammatory factors and histopathologic examination. T1-mapping values were measured using a modified look-locker inversion-recovery sequence in all participants.

RESULTS

The positive rate of pathological diagnosed AIT was only 83.3% in the AIT group diagnosed by positive TPOAb and/or TgAb and typical ultrasonic manifestations, while 7.1% of the control group was diagnosed as AIT by pathological manifestations. Receiver operating characteristic curve analysis revealed a very high diagnostic value of thyroid T1-mapping values for pathological diagnosed AIT (area under the curve was 0.950, 95%CI: 0.843 - 0.993, P < 0.001). In the patients with pathological diagnosed AIT, thyroid T1-mapping values were significantly associated with the mRNA expression of INF-γ (r = 0.343, P < 0.05), TNF-α (r = 0.352, P < 0.01), and IL-1β (r = 0.673, P < 0.01) in thyroid tissues. Moreover, histopathologic examination showed that thyroid T1-mapping values can properly reflect the degree of thyroid destruction in AIT patients.

CONCLUSIONS

Thyroid T1-mapping values had a very high diagnostic value for AIT. In euthyroid AIT patients, thyroid T1-mapping values better reflect degree of intrathyroidal inflammation and destruction.

l-Thyroxine induces left ventricular remodeling and fibrosis in rats by upregulating miR-21 in a reactive oxygen-dependent mechanism: a protective role of N-acetylcysteine

miR-21 is the most studied pro-fibrotic marker in the majority of mammalian tissues. The precise mechanism by which hyperthyroidism induces left ventricular LV fibrosis and remodeling remains unclear. In this study, we have investigated the role of miR-21 on l-thyroxine (l-Thy)-induced cardiac fibrosis in rats. Adult male Sprague-Dawley rats were divided into four groups as control, l-Thy, l-Thy + miR antagomir (inhibitor), and l-Thy + N-acetylcysteine (NAC/glutathione (GSH) precursor). Administration of l-Thy significantly increased mRNA levels of miR-21 in the LVs of the treated rats. Also, it impaired the LV systolic and diastolic function and increased the production of reactive oxygen species (ROS), the transactivation of NF-κB p65, the expression of NRLP3 inflammasome, and levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in these LVs. Concomitantly, l-Thy increased the ventricular collagen deposition, and stimulated the expression of collagen 1/3, alpha-smooth actin (α-SMA), transforming growth factor-β1, and Smad3/p-Smad3 but suppressed the expression of Smad7. All these effects were reversed by pre-treatment with miR-21 antagomir or co-administration of NAC. In conclusion, l-Thy-induced LV remodeling and fibrosis include a ROS-dependent upregulation of miR-21 which in turns activates NF-κB/NRLP3 inflammasome and suppresses SMad7.

Irisin as a Potential Biomarker Associated with Myocardial Injuries in Patients with Severe Hypothyroidism

OBJECTIVE

Irisin, a novel myokine, has recently been considered to produce a cardioprotective effect. Potential biomarkers for myocardial injuries in patients with severe hypothyroidism have yet to be identified. We aimed to investigate whether serum irisin may serve as a promising biomarker for early detecting the myocardial injuries in patients with severe hypothyroidism.

METHODS

This cross-sectional study comprised 25 newly diagnosed drug-naive patients with severe primary hypothyroidism and 17 age- and sex-matched healthy controls. Circulating irisin levels and cardiac magnetic resonance (CMR) were evaluated in each participant. Left ventricular (LV) myocardial injuries were detected by CMR-based T1 mapping technique using a modified look-locker inversion recovery (MOLLI) sequence, which is quantified as native T1 values.

RESULTS

Compared with healthy controls, the severe hypothyroidism group had significantly lower levels of serum irisin, especially those with pericardial effusion (P < 0.05). The severe hypothyroidism subjects exhibited lower peak filling rates (PFRs) and higher native myocardial T1 values than controls (P < 0.05). Additionally, the ROC analysis displayed that the sensitivity and specificity of serum irisin for diagnosing pericardial effusion in patients with severe hypothyroidism were 73.3% and 100.0%, respectively. The AUC was 0.920 (0.861-1.000) (P < 0.001). The cutoff value was 36.94 ng/mL. Moreover, the results in subgroup analysis revealed that the native T1 values of the low-irisin group were significantly higher than that of the high-irisin group (P < 0.05). According to multivariate linear regression analysis, serum irisin concentrations were negatively and independently correlated with native myocardial T1 values after adjustment for age, sex, and other conventional confounding factors (β = -1.473, P < 0.05).

CONCLUSIONS

Irisin may be a potential biomarker for predicting myocardial injuries in patients with severe hypothyroidism.

Thyroid Function and the Risk of Fibrosis of the Liver, Heart, and Lung in Humans: A Systematic Review and Meta-Analysis

Background: Fibrotic diseases have an unclear etiology and poor prognosis. Fluctuations in thyroid function may play a role in the development of fibrosis, but evidence is fragmented and inconclusive. This systematic review and meta-analysis aimed to investigate the association of thyroid function with fibrotic diseases of the liver, heart, and lung in humans. Methods: We searched PubMed, Medline Ovid, Embase Ovid, and Web-of-Science for studies published from inception to 14 June 2019, to identify observational studies that investigated the association of thyroid function with fibrosis of the liver, heart, and lung in humans. Study quality was evaluated by the Newcastle-Ottawa Scale. The Mantel-Haenszel method was used to pool the odds ratios (ORs) of studies investigating the association of hypothyroidism with liver fibrosis. Results: Of the 2196 identified articles, 18 studies were included in the systematic review, of which 11 studies reported on liver fibrosis, 4 on myocardial fibrosis, and 3 on pulmonary fibrosis. The population sample size ranged from 36 to 7259 subjects, with median mean age 51 years (range, 36-69) and median percentage of women 53 (range, 17-100). The risk of bias of studies was low to moderate to high. Higher serum thyrotropin and lower thyroid hormone levels were generally associated with higher likelihood of fibrosis. Compared with euthyroidism, overt and subclinical hypothyroidism was associated with a higher likelihood of fibrosis in the liver (six of seven studies), heart (three of three studies), and lung (three of three studies). Based on the results of the seven studies included in the meta-analysis, overt and subclinical hypothyroidism was associated with an increased risk of liver fibrosis (pooled OR, 2.81; 95% confidence interval [CI], 1.74-4.53; heterogeneity, I² 31.4%; pooled OR, 2.12; CI, 1.45-3.12; heterogeneity, I² 0%; respectively), without evidence of publication bias. Conclusions: This study suggests that low thyroid function is associated with increased likelihood of chronic fibrotic diseases of the liver, heart, and lung. However, the evidence is mainly based on cross-sectional data. Prospective studies and randomized clinical trials are needed to investigate the potential efficacy of thyroid hormone and its analogs on the occurrence and progression of fibrosis.

Impact of Hypothyroidism on Echocardiographic Characteristics of Patients With Heart Valve Disease: A Single-Center Propensity Score-Based Study

Background: Hypothyroidism is known to be correlated with multiple heart diseases. However, the influence of hypothyroidism on the patients with heart valve disease (HVD) is still unclear. The purpose of our study was to investigate the impact of hypothyroidism on echocardiographic characteristics of patients with heart valve disease. Methods: We conducted a retrospective cohort study which included 2,128 patients with HVD, and they were divided into euthyroid, subclinical hypothyroidism (SCHypoT), and overt hypothyroidism (OHypoT) group. Echocardiographic characteristics before and after valve surgery between groups were compared by using propensity score (PS) analysis. Kaplan-Meier analysis was used to compare the percent of recovery of left atrial (LA) enlargement between groups. Results: Overall, 463 patients had hypothyroidism (404 SCHypoT patients and 59 OHypoT patients), and 1,665 patients were euthyroid. At baseline, hypothyroidism was associated with significantly higher left atrial diameter (LAD), interventricular septum thickness, left ventricular posterior wall thickness, pulmonary artery systolic pressure, and lower left ventricular ejection fraction. After valve surgery, only LAD remained significantly higher in the patients with hypothyroidism. Additionally, patients with hypothyroidism had a significantly lower recovery rate of LA enlargement after valve surgery compared with euthyroid patients. Conclusion: Hypothyroidism was associated with a larger LAD in patients with HVD before and after surgery, which may suggest that hypothyroidism is a risk factor of LA enlargement of HVD. Besides, hypothyroidism was associated with a significantly lower recovery rate of LA enlargement after valve surgery.

Levothyroxine Replacement Alleviates Thyroid Destruction in Hypothyroid Patients With Autoimmune Thyroiditis: Evidence From a Thyroid MRI Study

Background: Autoimmune thyroiditis (AIT) is the most frequent cause of hypothyroidism. Our previous studies have shown that magnetic resonance T1-mapping is a new technique for quantitatively evaluating the degree of thyroid destruction in AIT patients. This study aimed to evaluate the effect of levothyroxine on thyroid destruction in hypothyroid AIT patients using thyroid T1-mapping technique. Methods: This study recruited 29 hypothyroid AIT patients and 18 age- and sex-matched healthy individuals. Thyroid T1-mapping values were measured in all participants and repeated in the AIT patients at 3 months after they achieved a euthyroid state following levothyroxine treatment. Results: Thyroid T1-mapping values were higher in the AIT patients than in the healthy controls (1167.2 ± 163.2 vs. 779.6 ± 83.8 ms, P < 0.01), and levothyroxine treatment significantly decreased the thyroid T1-mapping values of AIT patients (1006.3 ± 114.6 vs. 1167.2 ± 163.2 ms, P < 0.01). Meanwhile, the reduced levels of anti-peroxidase antibody (TPOAb) and anti-thyroglobulin antibody (TgAb) were observed in the AIT patients after levothyroxine treatment [TPOAb: 257.6 (23.9-960.6) vs. 1,287.4 (12.6-2000.0) IU/mL, P < 0.01; TgAb: 53.54 (9.58-386.2) vs. 103.9 (34.2-1,596.8) IU/mL, P < 0.05]. High-sensitivity C-reactive protein (hsCRP) levels showed a descending tendency following levothyroxine treatment, although there was no statistical difference (P > 0.05). Conclusions: In the AIT patients, thyroid T1-mapping values were significantly increased, and levothyroxine treatment significantly decreased the thyroid T1-mapping values of the AIT patients. These results might suggest that levothyroxine treatment alleviates thyroid destruction in hypothyroid AIT patients.

Magnetic resonance T1-mapping evaluates the degree of thyroid destruction in patients with autoimmune thyroiditis

OBJECTIVE

Autoimmune thyroiditis (AIT) is the most common autoimmune thyroid disease. Longitudinal relaxation time mapping (T1-mapping) measured by MRI is a new technique for assessing interstitial fibrosis of some organs, such as heart and liver. This study aimed to evaluate the relationship between T1-mapping value and thyroid function and determine the usefulness of T1-mapping in identifying thyroid destruction in AIT patients.

METHODS

This case-control study recruited 57 drug-naïve AIT patients and 17 healthy controls. All participants were given thyroid MRI, and T1-mapping values were measured using a modified look-locker inversion-recovery sequence.

RESULTS

AIT patients had significantly higher thyroid T1-mapping values than the healthy controls (1.077 ± 177 vs 778 ± 82.9 ms; P < 0.01). A significant increase in thyroid T1-mapping values was presented along with the increased severity of thyroid dysfunction (P < 0.01). Correlation analyses showed that increased thyroid T1-mapping values were associated with higher TSH and lower FT3 and FT4 levels (TSH: r = 0.75; FT3: r = -0.47; FT4: r = -0.72; all P < 0.01). Receiver-operating characteristic curve analysis revealed a high diagnostic value of T1-mapping values for the degree of thyroid destruction (area under the curve was 0.95, 95% CI: 0.90-0.99, P < 0.01).

CONCLUSIONS

AIT patients have higher thyroid T1-mapping values than the healthy controls, and the T1-mapping values increased with the progression of thyroid dysfunction. Thyroid T1-mapping value might be a new index to quantitatively evaluate the degree of thyroid destruction in AIT patients.

Diffuse Myocardial Injuries are Present in Subclinical Hypothyroidism: A Clinical Study Using Myocardial T1-mapping Quantification

Subclinical hypothyroidism (SHT) is a common disorder that may represent early thyroid dysfunction and is related to adverse cardiovascular events. However, myocardial injuries induced by SHT are difficult to detect. Our previous study demonstrated that the cardiac magnetic resonance (CMR) myocardial longitudinal relaxation time (T1) mapping technique is a useful tool for assessing diffuse myocardial injuries in overt hypothyroidism patients. This study was designed to detect whether diffuse myocardial injuries were present in SHT by using the T1 mapping technique. We found that SHT participants had significantly increased native T1 values within four segments of the left ventricle (all p < 0.01), especially patients with thyroid-stimulating hormone (TSH) levels ≥10 µIU/mL, compared with those in the controls. In addition, the native T1 values were negatively correlated with free thyroxine (FT4) (r = −0.476, p = 0.003) and were positively correlated with TSH (r = 0.489, p = 0.002). Furthermore, left ventricular diastolic function estimated by the peak filling rate (PFR) was significantly lower in patients with TSH levels ≥10 µIU/mL than that in the controls (p < 0.05). In conclusion, diffuse myocardial injuries were present in SHT, and T1 mapping may be a useful tool for evaluating mild myocardial injuries in SHT at an early stage. Our study is the first to confirm myocardial injuries in SHT patients using T1 mapping.

Hypothyroidism

Hypothyroidism is a common condition of thyroid hormone deficiency, which is readily diagnosed and managed but potentially fatal in severe cases if untreated. The definition of hypothyroidism is based on statistical reference ranges of the relevant biochemical parameters and is increasingly a matter of debate. Clinical manifestations of hypothyroidism range from life threatening to no signs or symptoms. The most common symptoms in adults are fatigue, lethargy, cold intolerance, weight gain, constipation, change in voice, and dry skin, but clinical presentation can differ with age and sex, among other factors. The standard treatment is thyroid hormone replacement therapy with levothyroxine. However, a substantial proportion of patients who reach biochemical treatment targets have persistent complaints. In this Seminar, we discuss the epidemiology, causes, and symptoms of hypothyroidism; summarise evidence on diagnosis, long-term risk, treatment, and management; and highlight future directions for research.