Lipid plaque density index as a phenotypic plaque feature which benefits from achieving LDL-C <55 mg/dL: Observations from the REASSURE-NIRS Multi-center Registry

Introduction Current ESC-guideline recommends achieving LDL-C level <55 mg/dL. Serial intravascular imaging studies demonstrated a greater plaque regression with more stabilization in association with substantially lowering LDL-C levels. However, plaque response to lowering LDL-C varies in each individual, suggesting the need to identify plaque phenotype who more likely benefits from this stringent LDL-C goal. Our recent study has developed a lipidic plaque density index, a novel plaque measure reflecting the degree of lipidic plaque materials within atheroma by using NIRS/IVUS. We hypothesized greater density of lipidic materials may favourably respond to achieving LDL-C <55 mg/dL, leading to better cardiovascular outcomes. Purpose To investigate the relationship of LPDI with cardiovascular outcomes in association with achieved LDL-C level <55 mg/dL. Methods The REASSUR-NIRS registry consecutively enrolled patients with CAD who received PCI under the guidance of PCI. All patients received a statin, and achieved LDL-C level was defined as on-treatment LDL-C level at 3 months after PCI. LPDI at non-culprit plaques was measured according to the following formula: maxLCBI4mm / atheroma volume at the corresponding 4-mm non-culprit segment. Primary outcome was defined as the occurrence of major cardiovascular events (=cardiac-cause death, non-fatal MI and unplanned revascularization). Patients were stratified according to median value of LPDI (=7.65). Then, clinical demographics and cardiovascular outcomes were compared in those with and without achieved LDL-C <55 mg/dL, respectively. Results The proportion of patients who achieved LDL-C <55 mg/dL was 32% and 31%, in low LPDI and high LPDI groups, respectively (p=0.84). In patients with low LPDI group, those with achieved LDL-C <55 mg/dL were older and more frequently received high-intensity statin. On NIRS/IVUS imaging analysis, there were no significant differences in atheroma volume, maxLCBI4mmand LPDI (Table1). During the observational period, achieved LD-C level <55 mg/dL was not necessarily associated with a reduction of MACE in patients with lower LPDI (Figure1). In patients with high LPDI, those with achieved LDL-C <55 mg/dL were less likely female with a greater frequency of ACS. Moreover, they were more likely to be treated with high-intensity statin. NIRS/IVUS-derived measured did not differ between two groups (Table 2). During the observational period, a greater reduction of MACE was observed in association with achieved LDL-C level <55 mg/dL (Figure). Conclusion Achieved LD-C level <55 mg/dL reduced a risk of MACE in patients with higher LPDI but not lower LPDI. Our findings highlight the importance to identify plaque phenotypes which better responds to lowering LDL-C level <55mg/dL. Imaging-guided lipid-lowering therapy may have potential to allocate personalized anti-atherosclerotic management, which leading to the improvement of cardiovascular outcomes.