Myocardial perfusion measured with magnetic resonance imaging in middle-aged and elderly adults with no clinical coronary heart disease.

摘要

The identification of coronary heart disease (CHD) before its clinical manifestation is very important for prevention programs. Over decades, a variety of methods have been used to detect subclinical CHD in individuals with no clinically diagnosed disease. Impaired coronary vasoreactivity is believed to be one of the earliest manifestations of coronary atherosclerosis. Noninvasive imaging studies of myocardial perfusion allow researchers to quantitatively estimate the reactivity of coronary vasculature and thereafter assess the subclinical atherosclerosis.;Our studies investigated myocardial perfusion in an asymptomatic middle-aged and older population. Study subjects were recruited from Minnesota participants in the Multi-Ethnic Study of Atherosclerosis (MESA), an ongoing population-based prospective cohort study of subclinical atherosclerosis. A total of 234 men and women, aged 45--84 years old and free of CHD diagnosis, underwent a magnetic resonance imaging (MRI) study of myocardial perfusion, at a mean of 9 months after their baseline MESA examinations. Myocardial blood flow (MBF) was measured at rest and during adenosine-induced hyperemia. Perfusion reserve (PR) was calculated as the ratio of hyperemic MBF divided by resting MBF. We studied the cross-sectional associations of coronary vasodilatory reactivity, as assessed by hyperemic MBF and PR, with CHD risk factors and other measurements of subclinical CHD.;After adjusting for age, gender and race, the association of low hyperemic MBF and PR with individual CHD risk factors was generally weak but reached statistical significance for hypertension, greater diastolic blood pressure, greater total cholesterol and LDL cholesterol. When the overall risk factor burden was estimated as predicted 10-year CHD risk using Framingham equations, hyperemic MBF and PR were correlated strongly and inversely with CHD risk factor burden. Hyperemic MBF and PR were also correlated strongly and inversely with the presence and severity of coronary artery calcification, measured with computed tomography, among middle-aged (45--64 years) subjects but not among older (65--84 years) subjects. An inverse association was also observed between hyperemic MBF, PR and urinary albumin excretion in middle-aged and older adults. This association was weak and not independent of age and gender. Our study results indicate that reduced coronary vasodilation can be detected in individuals with subclinical atherosclerosis.