P2239The association between global coronary flow reserve and coronary inflammation assessed by fat attenuation index on computed tomography in patients with acute coronary syndrome
Authors: Kanaji Y , Sugiyama T , Hoshino M , Hirano H , Horie T , Kanno Y , Ohya H , Sumino Y , Hada M , Yamaguchi M , Yuki H , Yonetsu T , Kakuta T 
Published: October 2019

Abstract

Background
Impaired global coronary flow reserve (G-CFR) is known to predict worse outcomes in patients with coronary artery disease. Phase contrast cine-magnetic resonance imaging (PC-CMR) of the coronary sinus (CS) is a promising approach for quantifying coronary sinus flow (CSF) and global coronary flow reserve (G-CFR) without the need for ionizing radiation, radioactive tracers, or intravascular catheterization. Although G-CFR impairment has been previously reported to be linked with endothelium dysfunction and subsequent atherosclerosis, the relationship between coronary inflammation and absolute coronary blood flow volume or coronary flow reserve remains elusive.

Purpose
We evaluated the association between G-CFR by quantifying CSF using PC-CMR and the extent of coronary inflammation in patients with ACS treated with emergent percutaneous coronary intervention (PCI).

Methods
The study enrolled 107 ACS patients who underwent uncomplicated emergent PCI within 48 hours of symptom onset and coronary CT angiography were performed before PCI. Proximal 40-mm segments of all three major epicardial coronary vessels were examined. Coronary inflammation was assessed by the CT fat attenuation index of perivascular adipose tissue (FAI−PVAT) defined as the mean attenuation of the perivascular adipose tissue (−190 to −30 Hounsfield units (HU)) in a layer of tissue within a radial distance from the outer coronary artery wall equal to the diameter of the vessel, as previously reported. CMR images were acquired to assess absolute CSF at rest and during maximum hyperemia within 30 days after emergent PCI and revascularization of non-culprit significant lesions. The patients were divided into 4 groups according to the number of inflamed vessels (defined as 0, 1, 2, 3 vessels with FAI ≥−70.1 HU).

Results
In the final analysis of 102 patients (mean age 64, Male 65 (63.7%)) including 77 patients with non-ST-segment elevation myocardial infarction (NSTEMI) (75.5%) and 25 patients with unstable angina pectoris (UAP), 25, 30, 26, 21 patients exhibited none, 1, 2, 3 inflamed vessels with FAI ≥−70.1 HU, respectively. Rest and maximal hyperemic CSF and corrected G-CFR were 1.17 [0.63, 1.71] vs 1.36 [1.05, 1.67] vs 1.21 [0.83, 1.94] vs 1.35 [0.96, 1.67] ml/min/g; P=0.61, 3.26 [2.62, 2.99] vs 3.50 [2.60, 4.03] vs 3.34 [1.78, 4.20] vs 2.48 [1.54, 3.43]; P=0.061, 2.95 [2.05, 4.30] vs 2.63 [1.80, 3.56] vs 2.15 [1.37, 2.91] vs 2.18 [1.46, 2.42]; P=0.018, respectively. G-CFR was significantly lower in group with increased number of inflamed vessels.

Conclusions
In ACS patients successfully revascularized within 48 hours of onset, G-CFR obtained by noninvasive PC-CMR significantly associated with the prevalence of inflamed vessels detected by coronary CT. Further large population study is warranted to test the hypothesis that the extent of coronary inflammation before coronary revascularization in patients with ACS might provide prognostic information.