Necessity and proper way of intermediate kissing balloon dilation for culotte stenting: further insights from bench testing

Objective: The aim of this study was to investigate whether intermediate kissing balloon dilation (IKBD) is necessary during mini-culotte stenting (MCS) and how it can be properly conducted. Methods: MCS was emulated in a bifurcation model with a branch diameter difference (BDD) in three-step sizes of 0.50, 0.75 and 1.00 mm, and with intermediate balloon dilation (IBD) in three treatments of routine intermediate solo balloon dilation (rISBD), concurrent IKBD (cIKBD) or sequential IKBD. Microcomputed tomography was performed to assess stent under-expansion (SUE) around the polygon of confluence (POC), residual ostial stenosis (ROS) at the ostial side-branch (SB) and main-branch (MB) and stent cell distortion (SCD) in the bifurcation segments. Results: There were both main and interactive effects of IBD and BDD on ROS at the ostial SB and SCD in the ostial SB, but there were only main effects of IBD or BDD on SUE around the POC, ROS at the ostial MB and SCD in the ostial MB. Analysis of the main effects showed that SUE around the POC or ROS at the ostial SB was significantly different between sIKBD and rISBD and between cIKBD and rISBD. There was also a significant difference in SCD in the ostial SB between sIKBD and rISBD and between sIKBD and cIKBD. Analysis of the interactive effects showed that ROS at the ostial SB or SCD in the ostial SB was affected by all IBD treatments in all BDD step-sizes. Moreover, increasing the BDD step-sizes significantly increased ROS at the ostial SB as treated by rISBD and SCD in the ostial SB as treated by rISBD or cIKBD. Conclusions: SIKBD was shown to be essential and superior to rISBD or cIKBD, resulting in better bifurcated stent expansion and coverage when using MCS.