Critical aspects of balloon position during final proximal optimization technique (POT) in coronary bifurcation stenting

Figure 1. Evaluated bifurcation stenting strategies. This investigation plan summarizes the three deployment strategies: the wire crossing site (proximal or distal), the side‐branch dilatation strategy, and balloon position during Final POT (across or proximal to the SB). With the culotte strategy, a metallic carina was induced by crossing in a position opposite to the carina in main vessel rewiring and through a proximal cell in side branch rewiring. KBI, kissing balloon inflation; OCT, optical coherence tomography; POT, proximal optimization technique; SB, side branch

Figure 2. Bench and analysis methods. (a) 3D OCT was used to evaluate the site of the wire crossing to the SB. In this instance, the position is proximal relative to the SB. (b) 3D microCT image with a stent in the main vessel and point of view for SB area measurements. (c) SB opening assessed by microCT. The largest cell opening area (yellow) and the reference area measured at origin of the carina (red), (c) shows the area before “Final POT” (C1) and after “Final POT” where the largest cell opening area has been reduced by Final POT across the SB (C2) as seen from the SB. (d) Pictogram, illustration the four different distance ratios at the SB ostium. For example, SBostium‐ratio1 = (White distance 1/Red distance). microCT, microcomputation tomography; OCT, optical coherence tomography; POT, proximal optimization technique; SB, side branch

Figure 3. Change in side branch cell opening area. Reduction in SB cell opening area (%) by Final POT is shown on the vertical axis for different bifurcation stenting strategies. Final POT across the SB is represented in blue and Final POT proximal to the SB in red. (a) One‐stent provisional strategy with kissing balloon inflation; (b) One‐stent provisional strategy with POT‐side‐POT technique; (c) Two‐stent culotte technique; (d) Pooled result. Final POT across the SB ostium causes a marked reduction in SB ostial area (red) in contrast to Final POT performed proximal to the SB ostium (blue). POT, proximal optimization technique; SB, side branch

Figure 4. Depicted are balloon positions during Final POT. Shown in (a) is Final POT with the balloon positioned across the SB origin and in (b) Final POT positioned proximal to the SB after single stent deployment and kissing balloon inflation. In A2, the metallic carina (yellow broken line) is pushed so that the SB is rejailed. microCT images viewed from the SB, show largest opening cell area in yellow and the reference area measured at origin carina in red. Final POT across the SB origin (A1 and A2) reduces SB ostial size (A3–A6) whereas Final POT proximal to the SB ostium (B1 and B2) does not move the metallic carina and has little of no effect on SB ostial size (B3–B6). microCT, microcomputation tomography; POT, proximal optimization technique; SB, side branch

Figure 5. Results of MSA, EI, and stent expansion before and after Final POT in one‐stent provisional stenting strategies with kissing balloon inflation. Results after either distal (a) or proximal (b) side branch wire crossings are shown. a1/Green box: The reference strategy with POT‐Kissing‐POT, distal cell SB wiring, and proximal Final POT. Results for all other techniques (including strategies on Figure 6) are in comparison to this strategy. Red bar charts indicate smaller measurements when compared to the reference. Green bar charts indicate larger measurements compared to the reference. Bar chart to the left: Results of OCT‐analyzes of the proximal stent segment. For the stent width in the bifurcation core segment (bar chart to the right), measurements were compared as ratio calculations at four positions (indicated with 1, 2, 3, and 4) (as described in Figure 2d). EI, ellipticity index; MSA, minimal stent area (mm2); OCT, optical coherence tomography; POT, proximal optimization technique; SB, side branch

Figure 6. Results of MSA, EI, and stent expansion before and after Final POT in one‐stent provisional stenting strategies with re‐POT. (a) Results after distal wire crossing. (b) Results after proximal wire crossings. Results are delta values for the comparison to the reference strategy marked with green in Figure 5 (POT‐Kissing‐POT, distal cell SB wiring, and proximal Final POT). Red bar charts indicate smaller measurements. Green bar charts indicate larger measurements. Bar chart to the left: Results of OCT‐analyzes of the proximal stent segment. For the stent width in the bifurcation core segment (bar chart to the right), measurements were compared as ratio calculations at four positions (indicated with 1, 2, 3, and 4) (as described in Figure 2d). EI, ellipticity index; MSA, minimal stent area (mm2); OCT, optical coherence tomography; POT, proximal optimization technique; SB, side branch