P360 Site specific phenotype of atherosclerotic lesions according to plaque location within the coronary tree, a CCTA based study

Funding Acknowledgements Research grant PlaqueImage, contract number 26/01.09.2016, SMIS code 103544, Project funded by the European Union and the Government of Romania Background The coronary CT angiography (CCTA)-based differences in composition, morphology and vulnerability of coronary plaques (CPs), according to their location within the coronary tree, have not been investigated so far. Purpose We sought to perform a comparative analysis between plaques located at different levels within the coronary tree, to identify the differences in plaque composition, morphology, and vulnerability between the three major coronary branches. Methods We conducted a cross-sectional, observational study on 75 patients with stable coronary artery disease who underwent CCTA for assessment of coronary lesions that exhibited at least one vulnerable plaque (VP) in the coronary tree. After image acquisition, coronary plaque analysis was performed with the use of the Syngo.via Frontier (Siemens) software. Plaque analysis also included evaluation of presence of VM: low attenuation plaque – LAP; napkin ring sign – NRS; spotty calcifications – SC; positive remodeling – PR. VP were defined as lesions that presented at least 1 vulnerability marker (VM). In total, 90 coronary VPs located at the level of the left anterior descending (LAD; n = 30), circumflex (CXA; n = 30) and right coronary artery respectively (RCA; n = 30) were identified and analyzed. Results Lesions located in the RCA presented a significantly higher length (LAD - 18.67± 5.49 vs. CXA - 15.48 ±3.73 vs. RCA - 20.47 ± 5.97 mm, p = 0.001), a higher degree of stenosis (LAD - 57.77 ± 8.62 vs. CXA - 54.50 ± 11.25 vs. RCA - 59.63 ± 10.42 mm, p = 0.022), and were more voluminous (LAD - 187.9 ± 86.03 vs. CXA - 146.9 ± 102.4 vs. RCA - 248.1 ± 11.4 mm3, p = 0.0007) compared to those located in the LAD and CXA, but no difference was observed regarding the remodeling (p = 0.180) or eccentricity indexes (p = 0.423). Plaque composition was also significantly different according to plaque location: calcified volume (LAD - 44.07 ± 63.90 vs. CXA - 12.40 ± 19.65 vs. RCA - 33.69 ± 34.38 mm3, p = 0.002), non-calcified volume (LAD - 143.8 ± 76.02 vs. CXA - 134.5 ± 102.2 vs. RCA - 214.4 ± 99.67 mm3, p = 0.002), lipid rich volume (LAD - 14.95 ± 22.69 vs. CXA - 6.44 ± 13.42 vs. RCA -16.07 ± 15.74 mm3, p = 0.0005), fibrotic volume (LAD - 128.9 ± 66.10 vs. CXA - 128.1 ± 91.56 vs. RCA - 198.3 ± 92.34 mm3, p = 0.003). The highest number of VM per plaque was present in the LAD (LAD - 2.2 ± 0.8 vs. CXA - 1.6 ± 0.7 vs. RCA - 1.8 ± 0.6, p = 0.01), as well as highest rate of VPs (LAD – 80%, CXA – 46.6%, RCA – 70%, p = 0.01). No difference was registered between coronary arteries on the presence of SCs (p = 0.670), NRS (p = 0.455), PR (p = 0.833), but LAPs were more frequently located in the LAD (p = 0.0009). Conclusions Coronary plaques located in the RCA were more voluminous and exhibited a higher volume of lipid rich and non-calcified atheroma. However, compared to the RCA and CXA, the left anterior descending artery presented CPs with a more expressed degree of vulnerability, a higher number of vulnerability markers per plaque, and a higher incidence of LAP.