Arterial Wall Stiffness and the Risk of Atherosclerosis in Egyptian Patients with Overt and Subclinical Hypothyroidism

Abstract

Objective: Hypothyroidism is associated with an increased risk of atherosclerosis. Pulse wave velocity (PWV) is an index of arterial wall stiffness widely used for noninvasive assessment of early atherosclerosis. We assessed PWV in Egyptian patients with hypothyroidism. Methods: The study included 100 Egyptian females aged 18 to 55 years. They were classified into three groups: group I, 40 women with overt hypothyroidism; group II, 40 women with subclinical hypothyroidism; and group III, 20 euthyroid women as a control group. The three groups were age matched. Doppler ultrasonography was used to calculate the heart-femoral PWV. Results: PWV was significantly higher in women with overt and subclinical hypothyroidism as compared with the control group (9.55 ± 1.81 m/s and 9.30 ± 1.28 m/s, respectively vs. 7.82 ± 2.14 m/s; P<.001 and <.01, respectively). There was a positive correlation between thyroid-stimulating hormone (TSH) and PWV in women with overt hypothyroidism and in those with subclinical hypothyroidism (P<.05 for both). Multivariate regression analysis showed that age and diastolic blood pressure were independent determinants of PWV in women with overt and subclinical hypothyroidism (P<.01 for all). TSH was also an independent determinant of PWV in both groups (P<.05 for both). Conclusion: PWV is significantly higher in Egyptian women with overt and subclinical hypothyroidism as compared with normal control subjects. This denotes early increase in arterial wall stiffness in patients with hypothyroidism, even in the subclinical phase. The positive correlation between PWV and TSH in both groups of patients suggests that the risk of atherosclerosis is proportionate to the severity of hypothyroidism. Abbreviations: ABI = ankle/brachial index; baPWV = brachial-ankle pulse wave velocity; BP = blood pressure; CIMT = carotid intima-media thickness; ECG = electrocardiogram; FT4 = free thyroxine; HDL = high-density lipoprotein; hfPWV = heart-femoral pulse wave velocity; LDL = low-density lipoprotein; PTT = pulse transit time; PWV = pulse wave velocity; SCH = subclinical hypothyroidism; TSH = thyroid-stimulating hormone.