Comparative analysis of lumen enlargement mechanisms achieved with the bifurcation dedicated BiOSS) stent versus classical coronary stent implantations by means of provisional side branch stenting strategy: an intravascular ultrasound study.

The aim of this study was to analyze the mechanisms of lumen enlargement in bifurcation lesions, as assessed by intravascular ultrasound (IVUS), after percutaneous treatment with classic provisional "T" stenting with conventional drug-eluting stents (DES) versus bifurcation dedicated BiOSS (Balton, Warsaw, Poland) stent. In this prospective study between Jan and Dec/11, 32 patients with single de novo coronary bifurcation lesions suitable for treatment with BiOSS stents were randomized (1:1). IVUS method included pre- and post-procedure analysis in the parent vessel. Vessel, lumen and plaque cross-sectional areas were determined at the target lesion [minimum lumen area (MLA) site], proximal limb, distal limb, and "window"-defined as the segment between the carina (flow divider) and the vessel wall at the level of the side branch inflow. All lesions were treated with provisional approach and only 1 case in BiOSS group had a stent implanted in the side branch. Angiographic and IVUS results including MLA at the target site and proximal/distal references were similar. However, mean window length-largest diameter within the window, was similar at baseline, but BiOSS measured significantly longer at postprocedure (2.21 ± 0.37 vs. 1.76 ± 0.52 mm, p = 0.01). In addition, the magnitude of changes in vessel (27 ± 24% vs. 9 ± 10%, p = 0.01) and plaque (2 ± 26% vs. -2 ± 26%, p = 0.02) areas at the window were significantly different for DES versus BiOSS groups, respectively. The contribution of vessel extension for lumen enlargement represented 54 versus 43%, 130 versus 46%, 98 versus 80% and 51 versus 19% of the result achieved at the proximal limb, window, distal limb and MLA sites for DES versus BiOSS, respectively; as for plaque re-distribution, results were 36 versus 57%, -30 versus 54%, 2 versus 20%, and 49 versus 81%, at the proximal limb, window, distal limb and MLA sites, respectively. These results suggest different mechanisms of lumen enlargement comparing conventional DES versus BiOSS dedicated bifurcation stent, which can impact side branch compromise during procedure.