Myocardial Flow Reserve in Coronary Artery Disease with Low Attenuation Plaque: Coronary CTA and 13N-ammonia PET Assessments.

Rationale and Objectives Physiological measurements from coronary angiography show that coronary stenosis with necrotic core plaque reduces coronary flow reserve (CFR). Myocardial flow reserve (MFR) estimated by 13N-ammonia PET (NH3-PET) is a different index from CFR. Low attenuation plaque (LAP) on coronary CTA (CCTA) contains necrotic core, but the link between LAP and MFR has not been elucidated. We aimed to investigate the influence of LAP on MFR in coronary artery disease (CAD). Materials and Methods The study included 105 consecutive patients who underwent NH3-PET and CCTA within 3 months. Nonevaluable coronary arteries due to severe calcification and stent implants were excluded. Finally, 290 major vessels were retrospectively analyzed. Coronary arteries were divided into mild (1%–49%), moderate (50%–69% stenosis), and severe (≥70% stenosis) groups. Coronary plaques were classified either LAP (including soft tissue CT value Results MFR was significantly lower for territories with LAP than with calcified plaques or no plaque (2.1 ± 0.7, 2.4 ± 0.7, and 2.3 ± 0.7; p Conclusion LAP reduced MFR compared with calcified plaque or no plaque in CAD. LAP is an independent predictor of the territory with MFR