The Prevalence of Left Ventricular Diastolic Dysfunction in Subclinical Hypothyroidism Patients

Abstract

Background: Elevated serum thyroid-stimulating hormone (TSH) levels together with normal blood levels of free thyroxine (FT4) and free triiodothyronine (FT3) are the hallmarks of subclinical hypothyroidism (SCH). SCH is common, especially in older persons and women, and it has been linked to a number of harmful cardiovascular consequences, such as left ventricular diastolic dysfunction (LVDD). The study investigated the incidence of LVDD in females with SCH and identify key predictors of this condition.

Methods: A total of 1,248 female patients aged 20 to 50 years with SCH were included. Inclusion criteria were elevated TSH (5-10 micro unit/L) with normal FT3 (2.77-5.27 pg/ml) and FT4 (0.78-2.19 ng/dl) levels. Patients underwent 2D Echocardiography to assess LVDD. Descriptive statistics, chi-square testing, and logistic regression analysis were used to analyse the data.

Result: LVDD was identified in 25% of the patients. The prevalence increased with age, being highest (28.2%) in the 40-50 age group. Significant associations were found between thyroid function and LVDD, with higher TSH and lower FT3 and FT4 levels linked to increased LVDD risk (p<0.001). Echocardiographic parameters showed higher LV mass and wall thickness in LVDD patients. Doppler echocardiographic parameters indicated impaired diastolic function. Logistic regression identified age, serum FT3, serum FT4, serum TSH levels, LV mass index, and E/A ratio as independent predictors of LVDD.

Conclusion: Female SCH patients have high rates of LVDD, which is linked to thyroid function. Older age and greater TSH were risk factors for LVDD, but higher FT3 and FT4 were protective. SCH individuals with LVDD had significant heart structural and functional abnormalities on echocardiography.

Recommendations: Regular cardiovascular screening and proactive management of thyroid function are recommended for patients with SCH to prevent the progression of cardiac dysfunction. Further research should explore the benefits of early intervention and the potential role of thyroid hormone replacement therapy in reducing cardiovascular risks.

Keywords: Subclinical hypothyroidism, Left ventricular diastolic dysfunction, Thyroid function, Echocardiography, Cardiovascular risk