SYNTAX score in relation to intravascular ultrasound and near-infrared spectroscopy for the assessment of atherosclerotic burden in patients with coronary artery disease.

Aims: The aim of this study was to examine the relationship between the anatomical SYNTAX score (SXscore), derived from all three coronary arteries, and coronary wall pathology measured by radio frequency intravascular ultrasound (RF-IVUS) and near-infrared spectroscopy (NIRS) in a single non-culprit segment. Methods and results: hi patients referred for coronary angiography (N=88) or PCI (N=592) for stable angina or acute coronary syndrome, the SYNTAX score calculator (www.syntaxscore.com) was used to determine the SXscore before PCI, if applicable. RF-IVUS and/or NIRS were performed in a non-stenotic 40 mm study segment following the clinically indicated angiography/PCI. After adjustment for multiple confounders, a higher SXscore was associated with higher segmental plaque volume in the study segment (2.21 mm(3) per SXscore point, 95% CI: 0.92-3.50, p-value 0.001), as well as with higher volume of fibrous (0.93 mm(3) per point) and fibro-fatty tissue (0.29 mm(3) per point). A higher SXscore was also associated with a higher NIRS-derived lipid core burden index (LCBI) in the full study segment (1.35 units per SXscore point, 95% CI: 0.22-2.47, p-value 0.019). Importantly, SXscore correlated with the fatty/fibro-fatty and LCBI signals despite adjusting for plaque burden. Conclusions: In patients with CAD, higher SXscores are associated with higher atherosclerotic burden as assessed by RF-IVUS and NIRS in a single non-stenotic coronary artery segment.