Objectives: This study sought to examine the relationship between inflammation and coronary microvascular function in asymptomatic individuals using positron emission tomography (PET) and assessment of coronary flow reserve (CFR).
Background: Coronary microvascular dysfunction is an early precursor of coronary artery disease (CAD) thought to result from endothelial cell activation and inflammation, but data are limited.
Methods: We examined 268 asymptomatic male monozygotic and dizygotic twins. Plasma biomarkers of inflammation and endothelial cell activation included C-reactive protein (CRP), interleukin (IL)-6, white blood cell count (WBC), vascular cell adhesion molecule (VCAM)-1, and intercellular adhesion molecule (ICAM)-1. Blood flow quantitation was obtained with [¹³N] ammonia PET at rest and after adenosine stress. CFR was measured as the ratio of maximum flow to baseline flow at rest; abnormal CFR was defined as a ratio < 2.5. A summed stress score for visible perfusion defects was calculated.
Results: In within-pair analyses, all biomarkers, except VCAM-1, were higher in twins with lower CFR than their brothers with higher CFR (p < 0.05). This was observed in the entire sample, as well as within pairs discordant for a CFR of <2.5. Associations persisted after adjusting for summed stress score and CAD risk factors. In contrast no biomarker, except IL-6, was related to the summed stress score of visible defects.
Conclusions: Even in asymptomatic subjects, a decrease in coronary microvascular function is accompanied by a systemic inflammatory response, independent of CAD risk factors. Our results, using a controlled twin design, highlight the importance of coronary microvascular function in the early phases of CAD.
Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.