Impact of plaque type and side branch geometry on side branch compromise after provisional stent implantation: a simulation study.

Aims: Mechanisms of lumen compromise after provisional side branch (SB) stenting are poorly understood. In this study we aimed to investigate the impact of bifurcation angle, plaque composition, and procedural strategy on SB compromise. Methods and results: Computer simulations of stent implantation were performed in Medina (1,1,1) bifurcation models. Provisional SB stenting was replicated including post-dilation after main branch stenting. Two bifurcation angles (45 degrees, 70 degrees) and four plaque types (fully lipid, fully fibrous, lipid with half and fully calcified ring distal to the carina) were tested. Two post-dilation balloons of different lengths (15 mm and 9 mm) were also investigated. Provisional stenting caused an ovalisation of the SB ostium (i.e., increase of ellipticity from 0.27 to 0.58 +/- 0.21, p<0.05) that might appear as a significant stenosis on two-dimensional angiography, although SB ostium area was preserved (-3.3 +/- 10.3%) in the absence of calcifications. However, in the presence of calcifications, SB lumen volume compromise was evident (-0.89 +/- 0.15 mm(3)). Plaque type had a higher impact than bifurcation angle on SB ostium shape. A shorter balloon (9 mm) for proximal optimisation reduced SB lumen volume compromise from -1.11 mm(3) to -0.72 mm(3). Conclusions: Simulations showed ovalisation of the SB ostium, generally without significant lumen compromise. Provisional stenting in the presence of calcifications resulted in a more severe outcome for the SB ostium.