SECONDARY DYSLIPIDEMIA AND ARTERIAL STIFFNESS IN ASYMPTOMIC PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM AND CAROTID ATHEROSCLEROSIS
Authors:   Belarusian State Medical University, E. B. Petrova , O. N. Shishko , M. G. Kaliadka , T. V. Statkevich , S. V. Chernyak , A. N. Popel , N. Ghanaatpishehsanani , A. A. Pleshko , N. P. Mitkovskay 
Published: September 2024

Secondary dyslipidemia accounts for 30–40% of all dyslipidemias and is a well-established risk factor for the development of atherosclerosis and its complications. The study of the contribution of endocrine pathology to cardiovascular risks and opportunities for prevention of cardiovascular complications is among the priority areas of healthcare worldwide. According to the World Health Organization, thyroid diseases hold one of the leading positions in the list of endocrine pathologies. Despite the high morbidity and mortality of patients worldwide due to cardiovascular diseases and considering the known success of healthcare in the prevention of the complications of atherothrombosis, there are still no clear therapeutic, diagnostic, and preventive guidelines in asymptomatic patients with concomitant endocrine pathology. Purpose of the study: to evaluate the relationship of cardiac-ankle vascular index (CAVI), ankle-brachial index (ABI) and brachiocephalic artery ultrasound findings and lipid profile in asymptomatic working-age patients with subclinical hypothyroidism. The design of the study. A cross-sectional cohort study analyzing data from 70 patients of working age with different thyroid hormonal status without clinical signs of chronic insufficiency of cerebral circulation. Materials and methods. The study included 70 persons of working-age without clinical signs of chronic insufficiency of cerebral circulation: 46 with laboratory-confirmed subclinical hypothyroidism (thyroid stimulating hormone (TSH) level > 4.0 mIU/L with normal thyroid hormone free fractions) and 24 patients without thyroid dysfunction. The groups were comparable in terms of age, sex, smoking, arterial hypertension. All patients underwent comparative analysis of lipid spectrum parameters (Total Cholesterol (TC), Triglycerides (TG), Low-Density Lipoprotein Cholesterol (LDL-C), High-Density Lipoprotein Cholesterol (HDL-C), Low- and High-Density Apolipoproteins) and ultrasound examination of carotid arteries. One of the used methods of preclinical diagnostics of atherosclerosis – volumetric sphygmography with assessment of cardiac-ankle vascular index (CAVI) and ankle-brachial index (ABI) – is described in detail in the article. Results. Patients with subclinical hypothyroidism exhibited significantly higher levels of TC, LDL-C, ApoB, ApoB/ApoA1 ratio, and atherogenic coefficient, and lower levels of HDL-C compared to patients without thyroid dysfunction. Additionally, a higher proportion of patients with subclinical hypothyroidism had elevated total cholesterol and LDL-C levels. Our data indicate that a significantly higher proportion of patients with subclinical hypothyroidism have atherogenic types of hyperlipidemia compared to those without thyroid dysfunction. Specifically, Type IIa hyperlipidemia was more prevalent in the subclinical hypothyroidism group. A direct, moderately strong association between elevated TSH level and atherogenic type of hyperlipidemia (r = 0.60; p < 0.01), atherosclerotic (r = 0.58; p < 0.01), multivessel (r = 0.54; p < 0.05) lesion of brachiocephalic arteries, presence of signs of atherosclerotic plaque instability (r = 0.64; p < 0.01) were found. In the group of patients with subclinical hypothyroidism, the proportion with low ABI was significantly higher: 34.7% (n = 16) vs 12.5% (n = 3) (F = 0.057; p < 0.05). A direct association between the reduced ABI value and the presence of ultrasound signs of multivessel atherosclerotic lesion of brachiocephalic arteries (r = 0.337, p < 0.001), and a negative association between ABI < 1.00 and atherogenic hyperlipidemia type IIa (r = 0.43; p < 0.05) were established. Conclusion. In clinically healthy working-age patients with subclinical hypothyroidism compared to those with normal thyroid function, there is a higher proportion of individuals with atherosclerotic multivessel lesions of the precerebral basin (32.6% (n = 15) vs. 8.3% (n = 2), χ² = 5.05; p < 0.05). The disease progression is associated with a background of atherogenic type 2a hyperlipidemia (93.5% (n = 43) vs. 70.8% (n = 17), χ² = 6.60; p < 0.05) combined with a deficiency of antiatherogenic high-density lipoproteins (HDL-C) (1.0±0.09 mmol/L vs. 1.3±0.06 mmol/L; p < 0.05).The etiopathogenetic mechanisms of “early vascular aging”, the criteria for stratification of risk groups for atherosclerosis-associated cardiovascular diseases, the selection of diagnostic algorithms for visualizing preclinical stages of atherogenesis, and timely antiatherogenic strategies in asymptomatic patients with comorbid thyroid pathology require further exploration. Active implementation in practical healthcare of the assessment of regional (segmental) vascular stiffness using volumetric sphygmography based on the characteristics of the main (CAVI) and peripheral (ABI) blood flow can be proposed for diagnosing preclinical stages of atherogenesis in comorbid patients with endocrinopathies. Verification of a stenosing hemodynamically significant or non-emodynamically significant atherosclerotic lesion of the coronary arteries, irrespective of the clinical component, is a factor of high cardiovascular risk necessitating immediate correction of hyperlipidemia.