Insights into the spatial distribution of lipid-rich plaques in relation to coronary artery bifurcations: An in-vivo optical coherence tomography study

OBJECTIVES: The aim of this study was to investigate the spatial location of vulnerable plaques at coronary artery bifurcations using frequency domain-optical coherence tomography. BACKGROUND: In-vivo data on geometric location of vulnerable plaques in relation to coronary bifurcation are limited. MATERIALS AND METHODS: A total of 40 patients with left anterior descending artery bifurcation were studied. Plaque characteristics in five regions in relation to a side branch were compared: opposite flow divider (OFD); bifurcation site (BF); main branch side proximal (MBP); side branch side proximal (SBP); and flow divider (FD). Frequency domain-optical coherence tomography was used for plaque characterization. RESULTS: Seventy-two lipid-rich plaques and 15 thin-cap fibroatheroma (TCFA) were detected in 220 regions of 44 bifurcations. Overall, the main branch side had more vulnerable characteristics compared with the side branch side. The FD was rarely affected by lipid accumulation. The OFD showed the highest prevalence of lipid-rich plaques [47.7% (OFD) vs. 45.5% (MBP), 43.2% (BF), 18.2% (SBP), and 9.1% (FD), P<0.0001] and TCFA [20.5% (OFD) vs. 6.8% (MBP), 6.8% (BF), 2.2% (SBP), and 0.0% (FD), P<0.001] and the thinnest fibrous cap [88.7±43.7μm (OFD) vs. 123.5±62.7μm (MBP), 149.6±77.0μm (BF), 157.4±65.4μm (SBP), and 163.6±76.9μm (FD), P=0.002] compared with other regions. CONCLUSION: Lipid accumulation tends to develop in the zone opposite the side branch. TCFA was localized predominantly in the region OFD, whereas FD was rarely affected.