Morphological and clinical implications of the optical coherence tomography-derived lipid core burden index

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Abstract Background Intracoronary optical coherence tomography (OCT) is a valuable tool for vulnerable plaque assessment and morphology-guided risk stratification. However the groundbreaking impact of OCT in clinical practice may be offset by its inherent limitation, the subjectivity in plaque interpretation. Recent studies reported a semi-automated method to assess fibrous cap thickness but data regarding an automated assessment of lipid component at OCT, such a lipid core burden index (LCBI), are lacking. Purpose The aim of this study was to assess the morphological characteristics and prognostic implications of an OCT-derived LCBI (OCT-LCBI). Methods In order to assess OCT-LCBI in 1003 patients with 1-year follow-up from the CLIMA multicenter registry (clinicaltrial.gov identifier NCT02883088) we used a novel previously validated software able to automate obtain a maximum OCT-LCBI in 4 mm (maxOCT-LCBI4mm). A maxOCT-LCBI4mm cut-off of 400 was used, based on previous literature on this topic. Primary composite clinical endpoint included cardiac death, myocardial infarction and target vessel revascularization. A secondary analysis using clinical outcomes of CLIMA study was performed. Results Patients with a maxOCT-LCBI4mm ≥400 showed higher prevalence of fibrous cap thickness <75μm (FCT, odds ratio [OR] 1.43, 95% confidence interval [CI] 1.03–1.99; p=0.034), lipid pool arc >180°(OR 3.93, 95% CI 2.97–5.21; p<0.001), minimum lumen area <3.5 mm2 (OR 1.5, 1.16–1.94; p=0.002), macrophage infiltration (OR 2.38, 95% CI 1.81–3.13; p<0.001) and intra-plaque intimal vasculature (OR 1.34, 95% CI 1.05–1.72, p=0.021). A maxOCT-LCBI4mm ≥400 predicted the primary endpoint (adjusted hazard ratio [HR] 1.86, 95% CI 1.1–3.2; p=0.019) as well as the CLIMA endpoint (HR 2.56, 95% CI 1.24–5.29; p=0.011). Patients with high lipid content and thin FCT <75 μm were at higher risk for adverse events (HR 4.88, 95% CI 2.44–9.72; p<0.001) (Figure 1). Conclusions We applied for the first time in a large population with clinical follow-up a software able to automatically obtain a maxOCT-LCBI4mm. A high maxOCT-LCBI4mm was related to vulnerable plaque features and further clinical events. This study represents a step further towards a comprehensive automated assessment of the coronary plaque risk profile. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Supported by a grant from the Centro per la Lotta contro l'Infarto – Fondazione Onlus, Rome, Italy