Abstract 12890: Prognostic Value of Relative Flow Reserve by Hybrid 13 N-ammonia Positron Emission Tomography/Magnetic Resonance Imaging in Coronary Artery Disease

Abstract

Background: 13 N-ammonia PET has been used to evaluate myocardial blood flow (MBF) and coronary flow reserve (CFR) quantitatively. Relative flow reserve (RFR) was defined as the ratio of hyperemic MBF in a stenotic area to hyperemic MBF in a normal perfused area. The aim of this study was to examine the prognostic value of RFR in patients with coronary artery disease (CAD). Methods: We enrolled consecutive 66 patients with suspected CAD who underwent hybrid 13 N-ammonia PET/MRI. Under vasodilator stress with intravenous injection of adenosine, MBF and CFR were calculated from dynamic acquisition of 13 N-ammonia PET. RFR was calculated as the ratio of hyperemic MBF of a stenotic myocardial area to hyperemic MBF of a non-stenotic reference vascular territory. MRI images were simultaneously acquired with PET. Left ventricular ejection fraction (LVEF) was calculated from cine mode MRI. The end points were defined as composite of all-cause death, sustained ventricular arrhythmia, hospitalization due to decompensated heart failure and coronary artery revascularization. Results: Over the median follow-up of 3.6 ± 1.3 years, there were 22 (33.3%) adverse cardiac events. Kaplan-Meier analysis demonstrated lower event free rates in patients with CFR < 2.0 (P < 0.01, Figure A) and RFR < 0.81 (P = 0.022, Figure B), but not in those with stress MBF < 1.34 (P = 0.295) and stress LVEF < 55% (P = 0.187). Univariate Cox regression analysis showed that abnormal RFR (< 0.81) was significantly associated with adverse events (HR 3.72, 95% CI 1.21-18.01, P = 0.02). Conclusion: RFR is a useful marker to predict cardiac adverse events in patients with CAD. It would be an alternative approach to perform only stress scan without rest scan to reduce radiation exposure and scan time.