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Coronary bifurcation revascularization needs to take account of the diameter differential between vessels and to limit side-branch obstruction (SBO). The self-apposing properties of the Xposition S™ stent (STENTYS, France) seem interesting in this regard. The present experimental fractal bench study determined the best provisional stenting technique using Xposition S™. Three sequential strategies were compared (n = 5/group): implantation alone, side-branch inflation (SBI), and re-POT (initial proximal optimization technique (POT) + SBI + final POT). 2D- and 3D-OCT analyses and micro-CT scan were performed to quantify the main mechanical results at each step. Of the three groups, SBI and re-POT provided better final results than implantation alone in terms of residual SBO (respectively, 24.6 ± 5.6% and 24.8 ± 5.0% vs. 46.5 ± 10.3%, p < 0.05) and malapposition (respectively, 0.9 ± 0.6% and 0.8 ± 0.4% vs. 3.8 ± 1.9%, p < 0.05). Unlike SBI, the two POTs of the re-POT sequence did not improve the final result. SBI, alone or as part of re-POT, systematically led to one connector breakage, whereas implantation alone maintained complete stent integrity (p < 0.05). In Xposition S™ implantation, SBI should be systematic, but not post-dilatation specifically dedicated to bifurcation stenting (i.e., POTs). However, global post-dilatation is still mandatory to prevent stent underexpansion due to untreated stenosis. [ABSTRACT FROM AUTHOR]

The proximal optimization technique (POT) in coronary bifurcation stenting improves apposition and side-branch obstruction. The POT balloon should be positioned with the distal radio-opaque marker at the carina cut plane. However, the real impact of positioning remains unknown. Synergy ™ stents (Boston Scientific, USA) were implanted on left-main fractal bench models. Initial POT was performed in 3 positions according to distal shoulder position (loss of balloon parallelism) relative to the carina cut plane (n = 5/group): i) "proximal", 1 mm before carina; ii) "medium", just at carina; iii) "distal", 1 mm after carina. Results were quantified on 2D- and 3D-OCT. Compared to implantation, initial POT improved malapposition in all positions ("proximal": 61.5 ± 1.4% vs. 5.1 ± 2.7%; "medium": 60.2 ± 2.4% vs. 1.3 ± 0.6%; "distal": 60.5 ± 2.9% vs. 1.1 ± 1.8%, p < 0.05). However, residual malapposition was greater in "proximal" position (p < 0.05). "Proximal", unlike "medium" or "distal" POT, also failed to improve side-branch obstruction. Conversely, "distal" POT significantly overstretched the main-branch ostium, with stent/artery ratio 1.22 ± 0.04 vs. 1.11 ± 0.07 for "medium" POT (p < 0.05). Shoulder positioning is essential to optimize the mechanical benefit of POT without main-branch overstretch (too distal position). Experimentally, the best position is just at the carina cut plane ("medium"). • POT balloon positioning is crucial in optimizing mechanical benefit in terms of apposition and side-branch obstruction. • The POT balloon should be positioned so that distal loss of parallelism occurs just at the carina cut plane. • Achieving this requires perfect knowledge of the specific balloon characteristics. [ABSTRACT FROM AUTHOR]