Clinical Importance of the LDL-C/Apolipoprotein B Ratio for Neointimal Formation after Everolimus-Eluting Stent Implantations

Aims: Smaller low-density lipoprotein (LDL) particle size has been suggested to result in the development of endothelial dysfunction, atherosclerosis, and in-stent restenosis (ISR); however, little is known regarding the impact of the LDL particle size on the neointima formation leading to ISR after everolimus-eluting stent (EES) implantation. Methods: In this study, we have included 100 patients to examine the relationship between an LDL-C/apolipoprotein B (Apo B) <= 1.2, reportedly representing the LDL particle size, and the neointimal characteristics using optical coherence tomography (OCT) and coronary angioscopy (CAS) during the follow-up coronary angiography (CAG) period (8.8 +/- 2.5 months) after EES implantation. We divided them into two groups: LDL-C/Apo B <= 1.2 group (low LDL-C/Apo B group, n=53) and LDL-C/Apo B >1.2 group (high LDL-C/Apo B group, n= 47). Results: The low LDL-C/Apo B group had a significantly larger neointimal volume (12.8 +/- 5.3 vs. 10.3 +/- 4.9 mm(3), p=0.021) and lower incidence of a neointimal homogeneous pattern (71 vs. 89 %), higher incidence of a neointimal heterogeneous pattern (25 vs. 9 %) (p= 0.006) and higher prevalence of macrophage accumulation (9 vs. 2 %) (p=0.030) as assessed via OCT, and, as per the CAS findings, a higher prevalence of yellow grade >= 2 (grade 2; adjusted residual: 2.94, grade 3; adjusted residual: 2.00, p= 0.017) than the high LDL-C/Apo B group. Conclusions: A low LDL-C/Apo B ratio was found to be strongly associated with neointimal proliferation and neointimal instability evidenced chronically by OCT and CAS. An LDL-C/Apo B <= 1.2 will be of aid in terms of identifying high-risk patients after EES implantation.