Abstract 2609: Coronary Vasomotion in Normal Subjects with Risk Factors for Atherosclerosis: Noninvasive Assessment
Introduction: Abnormal coronary vasomotion, due to endothelial dysfunction and/or abnormal autonomic regulation occurs at early stage in the progression to overt coronary artery stenosis and can be detected using acetylcholine or the cold pressor test (CPT) during invasive angiography. CPT responses in asymptomatic subjects without stenosis are largely unknown. We devised a non-invasive cardiac MRI (CMR) method to evaluate coronary vasomotion in response to CPT.
Methods: We compared left anterior descending artery (LAD) vasomotion non-invasively in non-diabetic subjects with (RISK, n=20) and without (NL, n=9) known risk factors for CAD (hypertension, smoking, hyperlipidemia and early family history), but no clinical history of CAD. At CMR, (Sonata, Siemens) localization of an optimal section of the proximal LAD was performed using 3D breath hold MRA. High-spatial resolution 2D breath-hold dark blood imaging of the proximal LAD (segmented TSE) was done and cross-section lumen area was determined at rest, during CPT and during administration of nitroglycerin (NTG) as an index of endothelium independent vasodilation.
Results: RISK subjects showed a reduction in LAD area (-7.19%) while NL subjects showed net vasodilation (+2.46%) respectively (p= 0.04). Despite an abnormal response to CPT, RISK patients showed vasodilation during NTG. Table⇓: Mean % change in LAD area between the two groups
Conclusion: Subjects with risk factors but no CAD have abnormal coronary vasomotion that reflects endothelial dysfunction and/or abnormal autonomic regulation. CMR permits noninvasive assessment of coronary vasomotor function in subjects at risk for coronary atherosclerosis.