Endothelial function in a healthy Norwegian population: Risk factors, age and gender in the HUNT3 survey
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Background: Endothelial dysfunction is an early sign of atherosclerosis, often assessed as impaired flow-mediated dilation (FMD) in the brachial artery. This measure of endothelial function correlates with the endothelium-dependent relaxation of coronary arteries and is a marker of coronary events and manifest vascular disease in the peripheral vascular bed. Aims: The present thesis aimed to determine the variation of endothelial function and prevalence of endothelial dysfunction in a healthy Norwegian population using FMD, and to explore associations between FMD and standard risk factors for cardiovascular disease. Methods: FMD was measured by ultrasonography during reactive hyperaemia in the brachial artery of 4739 adults who were free from self-reported cardiovascular or pulmonary disease. Data were collected from June 2007 through July 2008. FMD and survey-data from the third wave of the health survey in Nord-Trøndelag (HUNT3) were combined with responses to a questionnaire assessing physical activity and use of tobacco. Variations in FMD across age and gender were analyzed by multiple linear regressions. Results: Mean FMD was 4.3 % for men and 5.3 % for women. In total, 17% had FMD ≤ 0%, indicating endothelial dysfunction. In both genders, FMD decreased with increasing age up to 70 years for men and up to 80 years for women. In men, FMD declined gradually after 30, in women, the decline was steepest around menopause; in women with hyperglycaemia, endothelial dysfunction was twice as frequent as in male counterparts. The presence of metabolic syndrome, high blood pressure and low VO2peak increased the prevalence of endothelial dysfunction more markedly in women than in men. Amongst men, FMD tended to be lower with non-smoking tobacco (snus) than in the non-tobacco users. This difference was even more pronounced in sedentary snus users. Conclusions: The age and gender distribution of FMD suggested that endothelial dysfunction precedes cardiovascular disease incidence by a about decade. Endothelial dysfunction was more strongly associated with cardiovascular risk factors in healthy women than in healthy men. This finding could explain why the metabolic syndrome, and especially hyperglycaemia, is associated with higher cardiovascular risk and worse prognosis in women.