Comparative assessment of “plaque/media” change on three modalities of IVUS immediately after implantation of either everolimus-eluting bioresorbable vascular scaffold or everolimus-eluting metallic stent in Absorb II study

Figures

• 

  Fig. 1. Study flow chart. BVS bioresorbable vascular scaffold, EES everolimus-eluting stent, IVUS intravascular ultrasound

• 

  Fig. 2. Cumulative frequency distribution curves of absolute ΔPV (mm3) pre- and post-implantation in device segment in BVS and EES groups. In BVS group, more than 70% of the lesions showed PV “increase” post-implantation; in EES group, approximately 50% of the lesions showed PV “increase” post-implantation. BVS bioresorbable vascular scaffold, EES everolimus-eluting stent, PV plaque/media volume

• 

  Fig. 3. Examples showing the overestimation and re-evaluations of plaque/media volume after implantation. The PA was over estimated from 7.4 to 8.7 mm2, as well as the PB (Pre: 58.2% vs. 64.9%) (Panels a, b). As IVUS lacks the necessary resolution to detect the true lumen border by differentiating the abluminal boundaries of device struts. The lumen contour is conventionally delineated along the endoluminal leading edge of the device. Therefore, device volumes and their backscattering are artifactually defined as “plaque/media volume” and was overestimated on grayscale-IVUS. PA was re-evaluated after subtraction of the pseudo “DC” on VH-IVUS and the Upper + Hyper EG which are surrogates for the device presence in both lesions (Panels c, d). One of the disadvantage of VH-IVUS is the default presence of medial stripe that masks and hides some of the struts in direct contact with the adventitia. Echogenicity is able to assess the plaque/media area without the hiding effect of the medial stripe of VH-IVUS. VA vessel area, LA lumen area, PA plaque/media area, PB plaque burden, VH-IVUS virtual histology-IVUS, EG echogenicity. *Side branches; DC dense calcium

• 

  Fig. 4. Compared to OCT, IVUS overestimates the plaque/media. Panels a and a′ show one patient who had undergone both IVUS (20 MHz) and OCT investigation, one cross section was matched using the side branch [5]. The lumen contour on IVUS mainly relies on the highly reflective endoluminal surface of the polymeric strut and may lack the necessary imaging resolution to detect the true boundaries of the vessel wall between the protruding polymeric struts. Therefore, IVUS may underestimate the lumen area and conversely overestimates the plaque/media area. In contrast, the contour of the true flow lumen area on OCT does not include artifactually the space filled with blood flowing between the protruding polymeric struts [5, 21]. SB side branch Reprinted with permission from Serruys et al. [5]