Abstract 2613: Physical Activity Independently Predicts Increased MRI Coronary Vasodilation to Nitroglycerin in Older Adults: The ADVANCE Study
Background: Exercise can improve vascular function but prior studies of coronary vasodilation have used invasive measures and small sample sizes. MRI allows noninvasive measurement of non-endothelium-dependent coronary vasodilation in response to nitroglycerin (NTG). We studied the correlation between physical activity and coronary vasodilation among asymptomatic older adults.
Methods: 1023 older adults without known cardiovascular disease were enrolled from Kaiser Permanente of Northern California for prospective evaluation as part of the Atherosclerotic Disease, Vascular Function and Genetic Epidemiology (ADVANCE) study. In a subset of 213 patients, physical activity was measured by the Stanford Seven-Day Physical Activity Recall, a validated questionnaire estimating energy expenditure in kcal/kg/day and NTG-induced coronary vasodilation was measured by MRI. Cross-sectional images of the mid right coronary artery were acquired pre and 5 min post 0.4mg sl NTG using a spiral coronary MRI sequence (in-plane resolution 0.7mm) on a 1.5T scanner. Coronary % vasodilation was determined from the ratio of post-NTG to pre-NTG cross-sectional area.
Results: Mean age was 66.0 ± 2.7 yrs and 33% were women. Mean NTG-induced coronary vasodilation was 24.0 ± 21.1% (median 20.8, interquartile range 28.4). Mean physical activity was 35.1 ± 3.4 kcal/kg/min. Linear regression analysis showed a significant positive correlation between the % coronary vasodilation and the degree of physical activity (beta=1.2; SE=0.41; p=0.003). This relationship remained significant (beta=1.3; SE=0.43; p=0.003) even after adjustment for age, gender, body-mass index, systolic blood pressure, total cholesterol/HDL ratio, cigarette smoking and diabetes. Higher physical activity level continued to be significantly associated with greater coronary vasodilation after further adjustment for coronary artery calcium score and use of vasoactive and statin medications (beta=1.2; SE=0.46; p=0.01).
Conclusions: In an asymptomatic older community patient sample, higher physical activity was associated with greater NTG-induced coronary vasodilation. Non-invasive measures of coronary function may aid in the assessment of preventive cardiovascular interventions.