P977 CT phenotype of high-risk atherosclerotic plaques causing an acute coronary syndrome compared to silent vulnerable plaques

Abstract

Abstract Funding Acknowledgements PlaqueImage.- research grant no. 103544/2016, contract number 26/01.09.2016 - Background Previous studies demonstrated that plaque morphology has a crucial role in the development of an acute coronary syndrome (ACS). However, not all vulnerable coronary plaques produce an ACS and the prediction power of various vulnerability features to predict an acute coronary event in a close future, has not been elucidated so far. Objective We aimed to use multi-slice computed tomography angiography (CTA) for assessment of morphological characteristics of culprit lesions producing an ACS in the next several months after CT assessment, in comparison with morphological characteristics of unstable coronary atherosclerotic plaques which did not trigger an ACS. Material and methods We analyzed 40 patients in whom CTA revealed presence of unstable coronary lesions, exhibiting at least one marker of vulnerability: napkin ring sign (NRS), spotty calcium (SC), positive remodeling (PR) or presence of low attenuation plaque (LAP), divided in 2 groups: group 1 - 20 patients who developed an ACS in the next 6 months following CTA examination, and group 2 – 20 patients matched for age, gender and risk factors, who did not present any cardiovascular event 6 month after CTA assessment. Post-processing of multi-slice CTA images was performed in order to assess morphological characteristics and CT-derived markers of atherosclerotic plaque instability. Results Similar mean values of plaque length (17.1 +/- 5.9 mm vs 16.9 +/- 3.4 mm; p = 0.6) and total atheroma volume (188.1 +/- 104.7 mm3vs 186.4 +/- 90.7 mm3; p = 0.8) were obtained for both groups. The mean number of vulnerability markers was 1.6 in group 1 vs 1.2 in group 2 (p = 0.07). However, atherosclerotic lesions in patients from group 1 presented significantly higher values of lipid-rich atheroma (9.8 +/- 10.8 mm3vs 2.6 +/- 1.0 mm3; p = 0.01) and remodeling index (1.14 +/- 0.3 in group 1 vs 0.89 +/- 0.19 in group 2, p = 0.04). At the same time, atheromatous plaques in patients who developed an ACS during the 6-months follow-up showed in a significantly higher proportion LAP (45% in group vs 10% in group 2, p = 0.03) and PR (15%in group 1 versus 5% in group 2, p = 0.04), but not NRS (30% vs 25%, p = ns) or SC (65% vs 40%, p = 0.2). Conclusions Atherosclerotic plaques producing an ACS exhibit a different phenotype than unstable plaques that remain silent. The CTA profile of atheromatous plaques producing an ACS includes the presence of low attenuation, positive remodeling, higher RI and lipid-rich atheroma. Presence of these features in high-risk coronary plaques identifies very high risk patients, who can benefit from adapted therapeutic strategy in order to prevent the development of an ACS.