Normal flow-mediated vasodilatation of the brachial artery and carotid artery intima-media thickness in subclinical hypothyroidism

Subclinical hypothyroidism (SHT) is a disease for which exact therapeutic approaches have not yet been established. Previous studies have suggested an association between SHT and coronary heart disease. Whether this association is related to SHT-induced changes in serum lipid levels or to endothelial dysfunction is unclear. The aim of this study was to determine endothelial function measured by the flow-mediated vasodilatation of the brachial artery and the carotid artery intima-media thickness (IMT) in a group of women with SHT compared with euthyroid subjects. Triglycerides, total cholesterol, HDL-C, LDL-C, apoprotein A (apo A), apo B, and lipoprotein(a) were also determined. Twenty-one patients with SHT (mean age: 42.4 ± 10.8 years and mean thyroid-stimulating hormone (TSH) levels: 8.2 ± 2.7 µIU/mL) and 21 euthyroid controls matched for body mass index, age and atherosclerotic risk factors (mean age: 44.2 ± 8.5 years and mean TSH levels: 1.4 ± 0.6 µIU/mL) participated in the study. Lipid parameters (except HDL-C and apo A, which were lower) and IMT values were higher in the common carotid and carotid bifurcation of SHT patients with positive serum thyroid peroxidase antibodies (TPO-Ab) (0.62 ± 0.2 and 0.62 ± 0.16 mm for the common carotid and carotid bifurcation, respectively) when compared with the negative TPO-Ab group (0.55 ± 0.24 and 0.58 ± 0.13 mm, for common carotid and carotid bifurcation, respectively). The difference was not statistically significant. We conclude that minimal thyroid dysfunction had no adverse effects on endothelial function in the population studied. Further investigation is warranted to assess whether subclinical hypothyroidism, with and without TPO-Ab-positive serology, has any effect on endothelial function.

Espessamento médio-intimal da carótida e função endotelial na doença arterial coronariana / Carotid intimal-medial thickening and endothelial function in coronary artery disease

OBJETIVO: Investigar uma correlação entre o teste de reatividade da artéria braquial (BART) e o espessamento médio-intimal (EMI) da carótida em uma população de pacientes com doença arterial coronariana, assim como avaliar uma correlação do BART e do EMI da carótida com a gravidade da doença arterial coronariana demonstrada através da coronariografia. MÉTODOS: Quarenta e dois pacientes (idade: 60,7 ± 9,2 anos, 66,7 por cento do sexo masculino) com doença arterial coronariana por coronariografia foram estudados. A função endotelial foi avaliada de modo não-invasivo através do BART, quando foi medido o porcentual de dilatação mediada pelo fluxo ( por centoDMF). O EMI de carótida foi avaliado por meio de ultra-som vascular. RESULTADOS: A média de por centoDMF foi de 4,7 ± 3,6 e a média de EMI de carótida foi de 1,08 ± 0,23 mm. As medidas do EMI de carótida e do por centoDMF apresentaram correlação estatisticamente significativa, com coeficiente de Spearman de -0,315, valor p = 0,042, demonstrando que valores menores de por centoDMF se correlacionaram a um maior EMI de carótida. Não houve correlação entre por centoDMF, EMI e a gravidade das lesões; CONCLUSÃO: A presença de uma correlação entre o por centoDMF e o EMI da carótida demonstra a concomitância de alterações vasculares funcionais e anatômicas na doença arterial coronariana, independentemente da gravidade das lesões ateroscleróticas.

Carotid intima-media thickness as an independent predictor of coronary artery disease.

BACKGROUND: A noninvasive technique of measuring carotid artery intima-media thickness has recently generated considerable interest as a marker of atherosclerosis and in the prediction of clinical coronary events and coronary artery disease. The present study evaluated the association of carotid artery intima-media thickness in the prediction of coronary artery disease in a western Indian population. METHODS AND RESULTS: Carotid artery intima-media thickness was measured with a B-mode scan in an ongoing study of 266 patients, who were further subdivided into 4 subgroups: those with non-insulin dependent diabetes mellitus; hypertension; diabetes mellitus with hypertension; and those without diabetes or hypertension (labeled as controls). The maximal intima-media thickness greater than 0.8 mm at the far wall of the common carotid artery, excluding raised lesions and plaques, was selected as the highest value for comparison. The subgroups were further divided into those with and without apparent coronary artery disease. A statistically significant intima-media thickness greater than 0.8 mm was observed in 59.2% of the subjects with coronary artery disease as against 40.8% in those without the disease on univariate analysis. A higher incidence of intima-media thickness of more than 0.8 mm was observed in all subgroups with coronary artery disease as against those without the disease, which was most marked in the hypertensive group (22.2% v. 3.6%) and contributed to the increased arterial thickness in diabetics with concomitant hypertension. Multivariate regression analysis revealed carotid artery intima-media thickness to be associated with coronary artery disease with an odds ratio of 2.40. CONCLUSIONS: Carotid artery intima-media thickness is a simple, noninvasive and reproducible clinical tool to evaluate atherosclerosis and predict coronary artery disease in Indian subjects. Prospective studies in a larger number of subjects, particularly in those undergoing coronary angiography, will help in establishing the role of this technique.