Endothelial-mediated coronary flow reserve in patients with mild thyroid hormone deficiency

Abstract

Context: Although coronary flow reserve (CFR) is reduced in patients with subclinical hypothyroidism (SHypo), the endothelial response of coronary vasomotion has never been explored in this clinical setting. Objective: To investigate the endothelial response of coronary flow in young and middle-aged patients with SHypo, without associated cardiovascular risk factors compared with healthy control subjects. Patients and methods:The study population consisted of 20 women (mean age 38.4C12.1 years) with newly diagnosed, untreated and persistent SHypo due to Hashimoto's thyroiditis. A total of 15 volunteers served as controls. Age, gender, body surface area, glucose, insulin levels, heart rate, systolic, diastolic, and mean blood pressure were similar in patients and controls. Body mass index was significantly higher in SHypo patients. Total cholesterol and low-density lipoprotein cholesterol, despite not significant, tended to be higher, and high-density lipoprotein cholesterol to be lower in SHypo. Coronary blood flow velocities were recorded in patients at rest and after the cold pressor test (CPT), a stimulus that can be considered totally endothelium-dependent. CFR was calculated as the ratio of hyperemic-to-resting diastolic peak velocities. Results: Coronary diastolic peak velocities at rest did not differ between the two groups but were significantly lower after CPT in patients with SHypo, thereby resulting in a lower CFR. The difference remained significant after adjusting resting and CPT velocities for the respective mean blood pressures. TSH was inversely correlated with CFR in the pooled population. Conclusion: Patients with SHypo without associated cardiovascular risk factors have a coronary endothelial dysfunction that appears in response to a physiological stimulus (the CPT).

MECHANISMS IN ENDOCRINOLOGY: Heart failure and thyroid dysfunction

“…This is in line with the results of some randomized and placebo-controlled studies that demonstrated (74,75,79,97,98). Diastolic dysfunction due to slowed myocardial relaxation and impaired ventricular filling is reversible after replacement therapy.…”

“…Diastolic dysfunction due to slowed myocardial relaxation and impaired ventricular filling is reversible after replacement therapy. Moreover, vascular function (systemic vascular resistance, arterial stiffness and endothelial function) and coronary flow reserve may improve significantly when euthyroidism is restored (74,75,79,97,98). The risk of HF was significantly lower in T 4 -treated patients than in untreated patients during the follow-up in the Cardiovascular Health Study (11).…”

Effects of TSH on the function of human umbilical vein endothelial cells

“…It is worth noting that endothelial cell dysfunction is generally accepted as an early step in the pathogenesis of AS, and impaired endothelial function has also been reported in patients with TH deficiency (Taddei et al 2003, Biondi et al 2009. Endothelial dysfunction, which is characterized by an imbalance between relaxing and contracting factors, between procoagulant and anticoagulant substances, and between proinflammatory and anti-inflammatory mediators, plays a particularly significant role in the pathogenesis of AS (Poredos 2002).…”

Association between subclinical hypothyroidism and diabetic nephropathy in patients with type 2 diabetes mellitus

“…Although SCH is usually asymptomatic, it has been associated with hyperlipidemia [1], atherosclerosis [2,3], cardiac dysfunction [4], and overt hypothyroidism [5]. An association between type 2 diabetes mellitus and SCH is not uncommon, with an SCH prevalence of 2.2-17% reported in previous studies [6][7][8].…”