Vasa Vasorum Restructuring in Human Atherosclerotic Plaque Vulnerability : A Clinical Optical Coherence Tomography Study

BackgroundPrevious studies have suggested that vasa vasorum (VV) is associated with plaque progression and vulnerability.ObjectivesThe aim of this study was to investigate the relationship between coronary neovascularization structures and plaque characteristics.MethodsWe included 53 patients who underwent optical coherence tomography to observe the proximal left anterior descending coronary artery. Patients were classified into 5 groups according to lesion characteristics: normal; fibrous plaque (FP); fibroatheroma (FA); plaque rupture (PR); and fibrocalcific plaque (FC). We defined signal-poor tubuloluminal structures recognized in cross-sectional and longitudinal profiles located in adventitial layer as VV, and within plaque as intraplaque neovessels. Two types of longitudinal microvascular structure (external running and internal running) and a particular type of intraplaque neovessels (a coral tree pattern) were noted. All VV and intraplaque neovessels were manually segmented followed by quantification with Simpson method.ResultsAmong the groups, there was significant difference (expressed as median [interquartile range (IQR)]) in VV volume (normal: 0.329 [IQR: 0.209 to 0.361] mm3, FP: 0.433 [IQR: 0.297 to 0.706] mm3, FA: 0.288 [IQR: 0.113 to 0.364] mm3, PR: 0.160 [IQR: 0.141 to 0.193] mm3, and FC: 0.106 [IQR: 0.053 to 0.165] mm3; p = 0.003) and intraplaque neovessels volume (normal: 0.00 [IQR: 0.00 to 0.00] mm3, FP: 0.00 [IQR: 0.00 to 0.00] mm3, FA: 0.028 [IQR: 0.019 to 0.041] mm3, PR: 0.035 [IQR: 0.026 to 0.042] mm3, and FC: 0.010 [IQR: 0.005 to 0.014] mm3; p < 0.001). Significant differences were observed in the prevalence of the internal running (normal: 0.0%, FP: 28.6%, FA: 40.0%, PR: 70.0%, and FC: 40.0%; p = 0.032) and the coral tree pattern (normal: 0.0%, FP: 7.1%, FA: 40.0%, PR: 80.0%, and FC: 10.0%; p < 0.01). The VV volume correlated with fibrous plaque volume (r = 0.71; p < 0.01).ConclusionsVV increase with fibrous plaque volume and intraplaque neovessels with particular structures are associated with plaque vulnerability. Imaging for microvasculature could become a new window for plaque vulnerability.