Dual-stent Techniques For Coronary Bifurcation Lesions: Bench Study For Simulation And Optimazation Of Morphology And Hemodynamics And Clinical Outcome Comparison For Different Stenting Techniques

Percutaneous coronary intervention(PCI) for treatment of coronary bifurcation lesions(CBL) reamins challengeable for interventionists. The dual-stent strategy has been a necessary option for treating true CBL or CBL with dominant vessel disease.None of the current dual-stent techniques can well recover the local morphology and/or hemodynamics in the bifurcation area,thereby failling to reduce the rates of instent restenosis(ISR) and instent thrombosis(IST).Our initial data showed that DK-mini-culotte firstly developed by us for treatment of complex CBL did have advantages over the other dual-stent techniques in terms of techinical feasibility and mid-term clinical outcomes. Accordingly, this project was to examine the difference of the local morphology and hemodynamics in the bifurcation area via simulating the current dominant dual-stent techniques by bench testing on silicone arterial bifurcation model, to compare the immediate and long-term clinical outcomes of stenting techniques for CBL,to identify the ideal dual-stent techniques, to explore the potential advantages of DK-mini-culotte.This study will provide the strategy for reducing ISR and IST as well as the foundmental data for optimizing the dual-stent techniques and for designing the new generation of stents customized for CBL.Part I Dual-Sent Techniques for Coronary Bifurcation Lesions: Bench Study for Simulation and Optimazation of Morphology and HemodynamicsObjectives: To identify the ideal dual-stent techniques for treating CBL and explore the potential advances of DK-mini-culotte by comparing the difference of the local morphology and hemodynamics in the bifurcation area via simulating the current dominant dual-stent techniques and DK-mini-culotte technique by bench testing.Methods: The whole release processes of classic crush, DK-crush, classic culotte and DK-mini-culotte were stimulated on silicone arterial bifurcation model and grouped according to the stenting techniques. The morphology features were compared by 3D focus camera shooting, micro focus CT and optical coherence tomography(OCT), and the occurrence of turbulence at each segment of the bifurcation were detected by the color Doppler flow imaging in the bifurcation area under the condition of steady flow.Results: Morphological study showed the following findings: The classic crush technique caused gaps resulting in incomplete stent coverage near the bifurcation carina with multiple layers of stent struts crushed against the lateral wall of the parent vessel(PV) and around the ostium of the side branch(SB).The DK-crush technique frequently created a crescent moon-like tube inside the PV due to the incomplete crush of the protrusion segment of the SB stent regardless of pre-embedding a bigger balloon in the main branch(MB) with higher inflation pressure, thus leading to subsequent difficulties of wiring, rewiring or device-passing. Also, there were three layers of stent struts crushed against the lateral wall of MB similar to the classic crush. The major limitations of classic culotte technique were the circular under-expansion band(CUEB) around the bifurcation arina despite of relatively homogeneous overlap of double layer of stent struts in PV. The DK-mini-culotte technique had no more CUEB existed, less overlap of double stent struts in MB and better apposition of metallic carina mainly owing to the first balloon kissing technique. Additionally, as compared to the classic crush and classic culotte, the DK-mini-culotte significantly increased the success of final balloon kiss(FBK)(P<0.05). The importance order of factors that affect the percentage area stenosis of SB ostium was listed as: the stenting techniques > the vessel diameter difference > the distal bifurcation angle by orthogonal experimental design, of which the stenting techniques and the vessel diameter difference were the dominant factors. The optimal combination was DK-mini-culotte technique, 0.5mm of the vessel diameter difference, and 45° of distal bifurcation angle by Duncan multiple comparison. Compared with classic crush and DK-crush techniques, the DK-mini-culotte technique significantly reduced the occurrence of turbulence around SB ostium(P<0.05).Conclusions: Bench study demonstrated there was significant difference of the vascular/stents morphology and hemodynamics among the dual-stent techniques. DK-mini-culotte had no more CUEB, less stents overlap, better apposition of metallic carina, bigger lumen area of SB ostium and fewer local turbulent fields around SB ostium. Such technical benefits afforded by DK-mini-culotte might further translate into reduction of ISR and IST, and make it being the better dual-stenting technique for CBL.Part II: Dual-Stent Techniques for Coronary Bifurcation Lesions: Comparison of Clinical Outcome with Different Stenting TechniquesObjectives: To compare the immediate and long-term outcomes of different stenting techniques for the treatment of CBL.Methods: A retrospective study was conducted for 232 patients treated with PCI for CBL. All patients were divided into crossover group and Dual-stent group according to the stenting techniques; and then the patients in dual-stenting group were divided into DK-crush subgroup, classic culotte subgroup and DK-mini-culotte subgroup. All patients were followed up for at least 9 months. The primary end point was the rate of the major adverse cardiac events(MACE), including cardiac death, myocardial infarction(MI), target lesion/vessel revascularization(TLR/TVR) and IST. The secondary end point was the rate of angiographic in-segment restenosis.Results: The rate of MACE was 20%(8/40 patients) with non-FBK and zero(0/49 patients) with FBK in the crossover group(P<0.05). The occurrence of MACE was not different between the crossover group and dual-stent group and among the dual-stenting subgroups. There was no difference in the rates of in-segment restenosis between the crossover group and dual-stent group, But the rates of in-segment restenosis in bifurcation site and SB were significantly higher in DK-crush subgroup compared to combined subgroup of classic culotte and DK-mini-culotte, respectively(36.0% vs 16.1%, 36.0% vs10.7%, P<0.05, respectively).Conclusions: Our data suggested that the dual-stent techniques was not superior to the mono-stent technique for treating CBL; the modified FBK was helpful to reduce MACE but ISR; The dual-stent techniques including DK-crush, classic culotte and DK-mini-culotte had similar occurence of MACE, but DK-crush might increase restenosis.