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

The Role of Global Longitudinal Strain in Subclinical Hypothyroid Patients With Heart Failure

Introduction There is considerable evidence to suggest the role of thyroid hormone in acute coronary syndrome (ACS), but less is known about its prognostic role in heart failure (HF). We aimed to assess the role of global longitudinal strain (GLS) in patients hospitalized with HF and underlying subclinical hypothyroidism (SCHS). Methods A retrospective analysis of 161 subjects was conducted by dichotomizing them into HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF) subgroups. SCHS was defined as a thyroid stimulating hormone level >4.50 mIU/L with a normal thyroxine level based on the evaluation of limits for lab markers from prior studies. HFpEF and HFrEF were defined as left ventricular ejection fraction (LVEF)>40% and LVEF≤40%, respectively, based on American College of Cardiology (ACC) guidelines. An abnormal speckled transthoracic echocardiographic (TTE) strain was defined as a left ventricular global longitudinal strain (LVGLS) value of >-15%. Results The mean age of the population was 62±8 years, and 55% were female. LVGLS was present in 121 patients with underlying SCHS (p<0.05). The patients with SCHS and abnormal LVGLS were found to have deranged left ventricular echocardiographic parameters (p<0.05). The derangements were greater for SCHS patients with HFrEF and abnormal LVGLS (p<0.05). Readmission rates at 30 days and in-hospital mortality were higher in SCHS patients with abnormal LVGLS (p<0.05). Conclusion The SCHS is associated with abnormal GLS in HF patients (either HFpEF or HFrEF) that results in remodeling and adverse outcomes, including mortality and readmission rates. Further studies are warranted to validate these findings in a larger population data pool.

The effect of over- and undertreatment of hypothyroidism on hospitalization outcomes of patients with decompensated heart failure

The effect of over- and undertreatment of hypothyroidism on hospitalization outcomes of patients with acute decompensated heart failure (HF) has not been evaluated yet. We conducted retrospective cohort analyses of outcomes among 231 consecutive patients with treated hypothyroidism who were admitted to internal medicine departments of Shamir Medical Center with HF (2011-2019). Patients were divided into three groups according to their thyroid-stimulating hormone (TSH) levels: well treated (TSH: 0.4-4 mIU/L), overtreated (TSH: <0.4 mIU/L), and undertreated (TSH: >4 mIU/L). The main outcomes were mortality and recurrent hospitalization within 3 months. Among 231 patients, 106 were euthyroid, 14 were overtreated, and 111 undertreated. Patients' mean age was 79.8 ± 9.4 years. In-hospital mortality occurred in 4.7% in euthyroid patients, 14.3% in the overtreated group, and 10.7% in the undertreated group (p = 0.183). Differences in 30-day (p = 0.287) and 90-day (p = 0.2) mortality or recurrent hospitalization (p = 0.438) were not significantly different as well. However, in patients who were markedly undertreated and overtreated (TSH: >10 mIU/L or below 0.4 mIU/L) compared with 0.4-10 mIU/L, a significant increase in 90-day mortality was observed (33.3% vs 15.1% p = 0.016). Treatment status was independently associated with 90-day mortality after controlling for confounders with an adjusted odds ratio of 3.55 (95% confidence interval: 1.39-9.06). Although mild under- or overtreatment of hypothyroidism does not have a significant detrimental effect on hospitalization outcomes of patients with acute decompensated HF, markedly under- and overtreatment are independently associated with rehospitalizations and 90-day mortality. Larger cohorts are needed to establish the relationship between treatment targets and hospitalization outcomes of patients at risk for HF hospitalization.

New-Onset Heart Failure in the Setting of T4-Conversion Disorder

Thyroid hormone is essential in accomplishing the appropriate metabolism of the body. Achieving euthyroidism is of importance due to the deadly ramifications of being hypothyroid, such as multiple organ failure, profound decrease in mentation and even death.

We present a case of an 80-year-old female with a history of hypertension, coronary artery disease, chronic kidney disease, hypothyroidism due to total thyroidectomy, and a cerebral vascular accident who presented with slurred speech, decreased appetite, dizziness and lethargy with new-onset weakness. She was adherent to all her medications. Her labs were significant for elevated thyroid-stimulating hormone, elevated free thyroxine, and low total triiodothyronine. Brain MRI revealed no acute pathology. She was given her home dose of Levothyroxine and was admitted to the telemetry unit for evaluation of her symptoms and abnormal thyroid panel. During her hospital course, she was found to have an abnormal rhythm and worsening lethargy. Subsequent electrocardiogram and laboratory values revealed new T-wave inversions and elevated troponin. An echocardiogram revealed a new severely reduced left ventricular function with severe global hypokinesis of the left ventricle and an ejection fraction of 30%. It was only after initiating combination therapy of levothyroxine and liothyronine that her symptoms and abnormal cardiac rhythm resolved. With this careful titration of the patient’s medication, we concluded that combination therapy was essential to the patient being euthyroid. This phenomenon was also cited in multiple literature, which warrants an investigation of a certain population’s inability to convert T4 to T3.

By sharing this case, we aim to aid providers with their differential diagnoses and bring to light a potential area of further investigation. Ultimately, by optimizing and tailoring these medications, we hope to improve their quality of life. 

Indicators of endothelial function and systemic immune inflammatory response in patients with chronic heart failure and coexisting primary hypothyroidism

Chronic heart failure is one of the leading causes of death globally, affecting 1.5 to 2% of the total world population and 2.9 to 3.9% of the total Western European population. Chronic heart failure often progresses rapidly in coexistence with endocrine pathology, namely hypothyroidism, that results in a more rapid development and further progression of endothelial dysfunction and the development of a systemic inflammatory response. The aim of our research was to study the levels of endothelin-1, C-reactive protein, tumor necrosis factor α and their correlation with the levels of thyroid-stimulating hormone, thyroxine in patients with chronic heart failure and coexisting hypothyroidism. There were examined 38 patients with chronic heart failure and coexisting hypothyroidism and 42 patients with chronic heart failure without hypothyroidism. The serum levels of endothelin-1, C-reactive protein, tumor necrosis factor α were determined by the enzyme-linked immunosorbent assay, while the levels of thyroid-stimulating hormone and thyroxine were determined by the electrochemiluminescence immunoassay. In patients with chronic heart failure and coexisting hypothyroidism, the levels of endothelin-1, C-reactive protein, and tumor necrosis factor α were 2.9, 1.5 and 2.27 times higher than those in patients without hypothyroidism. In Group I, there was a moderate positive correlation between the serum levels of endothelin-1 and thyroid-stimulating hormone and a weak negative correlation between the levels of thyroxine and endothelin-1. In Group II, there was a weak correlation between the levels of endothelin-1 and thyroid-stimulating hormone and no correlation between the levels of thyroxine and endothelin-1. In Group I, there was a strong positive correlation between C-reactive protein and thyroid-stimulating hormone levels as well; in Group II, no similar correlation was found. In Group I, there was found a moderate negative correlation between tumor necrosis factor α and thyroxine levels. According to our results, there was a close correlation between the markers of endothelial dysfunction, immune inflammatory response, and single markers of hypothyroidism.

Subclinical Hypothyroidism in Geriatric Population and Its Association With Heart Failure

Heart failure (HF) is one of the most common causes of hospitalization in the geriatric age group, above 65 years. It is associated with high morbidity, mortality, and bad prognosis. Subclinical hypothyroidism (SCH) is a common condition present in this age group that significantly affects the cardiovascular system. Thus, this review attempts to elaborate on the association between subclinical hypothyroidism and heart failure in terms of their prevalence, pathogenesis, prognosis, and possible management in a geriatric age group. Among the various published literature on this topic on PubMed, PubMed Central, and Google Scholar, 36 relevant studies were selected to correlate this association. We found that both SCH and HF can be present concurrently in this age group. Especially in the geriatric population with thyroid-stimulating hormone (TSH) higher than ten mIu/L, there is an increased incidence of heart failure and a worse prognosis with preexisting heart failure. However, randomized controlled trials will be needed to explore further whether treatment is warranted or not in this age group.