Serial intravascular ultrasound analysis comparing double kissing and classical crush stenting for coronary bifurcation lesions

Background : Compared with the classical crush, double kissing (DK) crush improved outcomes in patients with coronary bifurcation lesions. However, there is no serial intravascular ultrasound (IVUS) comparisons between these two techniques. Objectives : This study aimed to analyze the mechanisms of the two crush stenting techniques using serial IVUS imaging. Methods : A total of 54 patients with IVUS images at baseline, post‐stenting and eight‐month follow‐up were classified into classical (n = 16) and DK (n = 38) groups. All patients underwent final kissing balloon inflation (FKBI). Unsatisfactory kissing (KUS) was defined as the presence of wrist or >20% stenosis during FKBI at the side branch (SB) ostium. The vessels at bifurcation lesions were divided into the proximal main vessel (MV) stent, the crushed segment, the distal MV stent, the SB ostium and the SB stent body. Results : KUS and incomplete crushing were commonly observed in the classical group (62.5%, 81.3%), compared with DK group (18.0%, 39.5%, P < 0.001 and P = 0.004). The post‐stenting stent symmetry in the classical group was 71.85 ± 7.69% relative to 85.93 ± 6.09% in DK group (P = 0.022), resulting in significant differences in neointimal hyperplasia (NIH, 1.60 ± 0.21 mm² vs. 0.85 ± 0.23 mm², P = 0.005), late lumen loss (1.31 ± 0.81 mm² vs. 0.55 ± 0.70 mm², P = 0.013), and minimal lumen area (MLA, 3.57 ± 1.52 mm² vs. 4.52 ± 1.40 mm^2, P = 0.042) at the SB ostium between two groups. KUS was positively correlated with the incomplete crush and was the only predictor of in‐stent‐restenosis (ISR) at the SB ostium. Conclusion : DK crush was associated with improved quality of the FKBI and larger MLA. KUS predicted the occurrence of ISR. © 2011 Wiley Periodicals, Inc.     

A “Jail Escape Technique” (JET) for distal side branch wiring during provisional stenting: Feasibility and first‐in‐man study

Objective

To evaluate the feasibility of a novel technique for achieving distal SB access and improve strut apposition during provisional stenting.

Background

While distal rewiring and stent expansion toward the side branch (SB) are associated with better results during provisional stenting of coronary artery bifurcation lesions, these techniques are technically challenging and often leave unopposed struts near the carina.

Methods

The “Jail Escape Technique” (JET) is performed by passing the proximal tip of the SB wire between the main vessel (MV) stent struts and balloon before implantation, allowing the MV stent to push the SB wire against the distal part of the carina. The MV stent can then be deployed without jailing the SB wire. Distal SB access and strut distribution at the carina were tested in phantom and swine models. Stent distortion, dislodgement forces, and material damage were evaluated with tensile testing. Human feasibility was then tested on 32 patients.

Results

Preclinical testing demonstrated that the SB wire was located at the most distal part of the carina and no strut malapposition at the carina was present after balloon inflation. Stent distortion, dislodgement forces, or material damage were not affected. JET was successfully performed in 30 of 32 patients. No major adverse cardiovascular events occurred in any patient at 6‐month follow‐up.

Conclusion

The “JET” enables distal SB access and eliminates strut malapposition at the carina. Further studies with larger numbers of patients are needed to further investigate this technique.

     

Comparative Analysis of Sequential Proximal Optimizing Technique Versus Kissing Balloon Inflation Technique in Provisional Bifurcation Stenting: Fractal Coronary Bifurcation Bench Test

ObjectivesThis study used a fractal bifurcation bench model to compare 6 optimization sequences for coronary bifurcation provisional stenting, including 1 novel sequence without kissing balloon inflation (KBI), comprising initial proximal optimizing technique (POT) + side-branch inflation (SBI) + final POT, called “re-POT.”BackgroundIn provisional bifurcation stenting, KBI fails to improve the rate of major adverse cardiac events. Proximal geometric deformation increases the rate of in-stent restenosis and target lesion revascularization.MethodsA bifurcation bench model was used to compare KBI alone, KBI after POT, KBI with asymmetric inflation pressure after POT, and 2 sequences without KBI: initial POT plus SBI, and initial POT plus SBI with final POT (called “re-POT”). For each protocol, 5 stents were tested using 2 different drug-eluting stent designs: that is, a total of 60 tests.ResultsCompared with the classic KBI-only sequence and those associating POT with modified KBI, the re-POT sequence gave significantly (p < 0.05) better geometric results: it reduced SB ostium stent-strut obstruction from 23.2 ± 6.0% to 5.6 ± 8.3%, provided perfect proximal stent apposition with almost perfect circularity (ellipticity index reduced from 1.23 ± 0.02 to 1.04 ± 0.01), reduced proximal area overstretch from 24.2 ± 7.6% to 8.0 ± 0.4%, and reduced global strut malapposition from 40 ± 6.2% to 2.6 ± 1.4%.ConclusionsIn comparison with 5 other techniques, the re-POT sequence significantly optimized the final result of provisional coronary bifurcation stenting, maintaining circular geometry while significantly reducing SB ostium strut obstruction and global strut malapposition. These experimental findings confirm that provisional stenting may be optimized more effectively without KBI using re-POT.     

光学相干断层成像评价药物洗脱支架置入术后晚期支架贴壁不良

目的 探讨药物洗脱支架(DES)置入术后晚期支架贴壁不良的特点.方法 分析32例(包括51支血管、共置入71个支架)置入DES 1年后[(14.8±5.2)个月]行光学相干断层成像(OCT)检查的患者资料,对支架节段的OCT图像每间隔0.5 mm取1帧图像进行分析,找出贴壁不良的支架金属结构,测量支架到参照血管内壁的距离及支架表面内膜厚度,分析晚期支架贴壁不良的特点.结果 OCT检查在7例(21.9%)患者中检出支架贴壁不良,其中4例合并支架段血管的正性重构,1例重叠置入支架,2例发现由血栓覆盖支架金属结构,7例患者随访期间无心脏不良事件发生.97.6%的支架金属结构完全贴壁并不同程度的内膜覆盖,2.4%的支架金属结构贴壁不良,包括1.2%的支架金属结构位于血管分支开口.位于血管分支开口的支架金属结构与其他贴壁不良支架表面的内膜覆盖厚度差异无统计学意义[(0.06±0.05)mm比(0.05±0.03)mm,P>0.05].绪论晚期支架贴壁不良见于DES置入最初的贴壁不良、血管壁正性重构、重叠置入支架以及支架金属结构位于分支血管开口;贴壁不良的支架金属结构表面亦有不同程度的内膜覆盖.     

Strategies for drug‐eluting stent treatment of bifurcation coronary artery disease in the United States: Insights from the e‐Cypher S.T.L.L.R.Trial

Objectives: Our goal is to report the first large multicenter data for percutaneous coronary intervention (PCI) of bifurcation disease with drug‐eluting stents (DES) in the United States. Background: Bifurcation PCI remains a challenge to this date. There are limited data on outcomes of patients treated with bifurcation DES implantation, particularly in the United States. Methods: There were 161 patients with bifurcation disease [side branch (SB) ≥2‐mm] treated with ≥1 sirolimus‐eluting stents at 41 centers participating in the Stent deployment Techniques on cLinicaL outcomes of patients treated with the cypheR?stent (STLLR) trial. There was no protocol mandated strategy for bifurcation PCI. One‐year outcome data were collected. Angiographic and clinical data were adjudicated independently. Results: There were 147 patients (91.3%) treated with single stent strategy. Only 14 (8.7%) patients received sirolimus‐eluting stents implantation in both branches. Among patients with single stent strategy, double wire strategy (DW) was selected in 27 (18.4%) patients whereas single wire strategy (SW) was selected in 120 (81.6%) patients. There were 48 (32.7%) Medina 1,1,1 bifurcations treated with SW (n = 34; 70.8%) and DW (n = 14; 29.2%). There were 26 procedures started with SW which had SB dilatation during the procedure, one as a bailout (TIMI‐1 grade flow in the SB). Overall 1‐year death, myocardial infarction, and target lesion revascularization occurred in 2.4, 4.0, and 5.6%, respectively. There was no significant difference in clinical outcomes between SW and DW. SB dilatation was associated with a high rate of stent thrombosis (8.6%). Conclusions: Main branch stenting without SB protection is the most common approach utilized in the STLLR study, which may reflect contemporary DES bifurcation strategies in the Unite States. This strategy was associated with an acceptable low incidence of adverse outcomes at 1‐year. © 2009 Wiley‐Liss, Inc.     

Bifurcation coronary lesions treated with the "crush" technique: an intravascular ultrasound analysis

OBJECTIVES: We report intravascular ultrasound (IVUS) findings after crush-stenting of bifurcation lesions. BACKGROUND: Preliminary results with the crush-stent technique are encouraging; however, isolated reports suggest that restenosis at the side branch (SB) ostium continues to be a problem. METHODS: Forty patients with bifurcation lesions underwent crush-stenting with the sirolimus-eluting stent. Postintervention IVUS was performed in both branches in 25 lesions and only the main vessel (MV) in 15 lesions; IVUS analysis included five distinct locations: MV proximal stent, crush area, distal stent, SB ostium, and SB distal stent. RESULTS: Overall, the MV minimum stent area was larger than the SB (6.7 +/- 1.7 mm2 vs. 4.4 +/- 1.4 mm2, p < 0.0001, respectively). When only the MV was considered, the minimum stent area was found in the crush area (rather than the proximal or MV distal stent) in 56%. When both the MV and the SB were considered, the minimum stent area was found at the SB ostium in 68%. The MV minimum stent area measured <4 mm2 in 8% of lesions and <5 mm2 in 20%. For the SB, a minimum stent area <4 mm2 was found in 44%, and a minimum stent area <5 mm2 in 76%, typically at the ostium. "Incomplete crushing"--incomplete apposition of SB or MV stent struts against the MV wall proximal to the carina--was seen in >60% of non-left main lesions. CONCLUSIONS: In the majority of bifurcation lesions treated with the crush technique, the smallest minimum stent area appeared at the SB ostium. This may contribute to a higher restenosis rate at this location.     

Extension Distance Mismatch—An Unrecognized Factor for Suboptimal Side Branch Ostial Coverage in Bifurcation Lesion Stenting

Background: The unsatisfactory side branch (SB) ostial strut coverage remains a problem in coronary bifurcation stenting. Both the surplus and lack of struts at SB ostium may be the causative mechanism. We propose that the inability of available stents to cover the “extension distance” of the bifurcation region is the cause of in‐stent restenosis. Methods: The extension distance (ED) is defined as the maximal distance at the carina tip, which must be covered by the stent struts to ensure optimal coverage of the main branch (MB) and SB openings. A mathematical model was created, representing the key factors that govern geometrical reconfigurations after stent implantation in bifurcations. There are two options—with and without bifurcation region deformation. The theoretical assumptions were tested on a bifurcation model (soft polyvinylchloride polymer tubes) permitting free wall deformations and the following parameters: Parent Vessel, MB, SB diameters of 3.5, 3.0, and 2.5 mm, respectively, with an angle of 45° between the MB and SB. After stenting, final KBI with 3.5 mm and 3.0 mm balloons was performed up to 20 atm. Results: After the carina displacement, the ED, which has to be covered, is considerably smaller if the suboptimal result (DS >50%) at the SB ostium is acceptable. The maximal EDs from the bench test measurements are: Vision, Abbott Vascular – 5.62 mm ± 0.04; Liberte, Boston Scientific Corp. – 5.2 mm ± 0.03; Chopin2, Balton – 4.58 mm ± 0.05; Volo, Invatec – 4.41 mm ± 0.04; Driver, Medtronics – 4.39 mm ± 0.04; BxSonic, Cordis, J&J – 4.48 mm ± 0.05. The theoretical maximal ED of the model is 6.91 mm—28–62% larger than actually observed with different stents. Conclusions: The achievement of perfect ostial coverage of the SB is unsatisfactory with most of the currently available stents, especially when poststenting excessive dilation of the ostium of the SB is performed. (J Interven Cardiol 2010;23:305–318)     

Clinical outcomes following bioresorbable scaffold implantation for bifurcation lesions: Overall outcomes and comparison between provisional and planned double stenting strategy

The aim of this study was to investigate clinical outcomes of patients treated with a provisional stenting (PS) versus a double stenting (DS) strategy for coronary bifurcation lesions with bioresorbable scaffolds (BRS). There are limited data available with regards to outcomes following BRS implantation for bifurcation lesions. A total of 132 bifurcation lesions treated with BRS between 2012 and 2014 were analyzed. Of the total of 132 bifurcation lesions, 10 lesions were treated without crossover stenting. 99 lesions (81%) were treated with a PS strategy and 23 lesions (19%) with a DS strategy. The DS group consisted of patients with a greater number of true bifurcation lesions (PS 52.0% vs. DS 91.3%: P < 0.001). In the PS group, seven lesions (7.1%) were crossed‐over to T‐stenting. In the DS group, 13 lesions (57%) were treated with BRS to the side branch (SB). A hybrid stenting technique [BRS to the main branch, and metallic drug‐eluting stent (DES) to the SB] was utilized in 10 (43%) lesions. Target lesion revascularization (TLR) rates were 5.5% for PS and 11.2% for DS (P = 0.49) at 1‐year follow‐up. Definite scaffold thrombosis did not occur at the site of any bifurcation lesion. These findings suggest that BRS implantation for bifurcation lesions is technically feasible. The rates of TLR tended to be higher in the DS group compared to when a PS strategy was employed. Larger studies are eagerly awaited to determine longer‐term follow‐up of this treatment strategy. © 2015 Wiley Periodicals, Inc.     

Location of side branch access critically affects results in bifurcation stenting: Insights from bench modeling and computational flow simulation

Background

The aim of this study was to evaluate the impact of stent design and side branch access on final strut apposition during bifurcation stenting.

Methods and results

A series of 6 different commercially available Drug Eluting Stents (DES) (n = 42) were deployed in an identical model of a coronary bifurcation. Kissing Balloon (KB) optimization was performed after either proximal or distal recrossing of the guidewire and results were analyzed by micro-Computed-Tomography.Stent design only had a minor impact on side branch lumen area free of stent struts. Similar rate of strut malapposition was observed within the bifurcation when a consistent KB optimization protocol and an optimal distal recrossing of the wire to reaccess the side branch (SB) are followed.Conversely, proximal instead of distal cell recrossing toward the side branch produced a significant lower area of the side branch lumen free of struts than an optimal distal recrossing (60.3 ± 7.1% versus 81.1 ± 8.0%, p < 0.0001), as well as a higher rate of strut malapposed toward the SB ostium (40.6 ± 6.0% versus 26.0 ± 5.7%, p = 0.0005).

Conclusions

Optimal cell recrossing of the guidewire may be critical to ensure successful stent optimization in bifurcation PCI.     

The glider balloon: A useful device for the treatment of bifurcation lesions

Background

Final kissing balloon dilatation (FKBD) is a recommended final step in case of treatment of bifurcation lesions by two stents approaches. Furthermore, dilatation of the side branch (SB) may be necessary following main vessel (MV) stenting. Occasionally, recrossing the stent struts with a balloon is hampered because the tip hits a stent strut.

Methods

The Glider (TriReme Medical, Pleasanton, CA) is a dedicated balloon designed for crossing through struts of deployed stents toward a SB. From October 2010 to January 2012, FKBD was attempted in 236 consecutive bifurcation lesions treated in our Institution. FKBD was successfully performed by conventional balloon catheters in 221 (93.5%) lesions (Conventional group). In the remaining 15 (6.5%) lesions, where a conventional balloon failed to cross the stent strut, the Glider balloon was attempted (Glider group).

Results

The angle beta (between the axis of the MV after the branch point and the SB axis at the point of divergence) was wider in the Glider group (83 ± 17° versus 65 ± 27°; p = 0.032). A trend toward an higher rate of the true bifurcation lesions was observed in the Glider group (93% versus 70.5%; p = 0.07). The Glider balloon successfully crossed through MV stent struts toward a SB in 12 patients (80%), whereas failed in the remaining 3 patients.

Conclusions

The Glider balloon represents an unique bail-out device which offers an effective rescue strategy for recrossing stent struts during complex bifurcation stenting.     

Difference of neointimal growth patterns in bifurcation lesions among four kinds of drug‐eluting stents

Aim: Neointimal proliferation of bifurcation lesions after implantation of drug‐eluting stents (DES) has not been well evaluated. Thus, we compared neointimal proliferation of bifurcation lesions among four DES using optical coherence tomography (OCT). Methods: 8‐month follow‐up OCT was performed in 68 bifurcation lesions treated by 15 sirolimus‐eluting stents (SES) and 17 paclitaxel‐eluting stents (PES) as first‐generation DES, and by 17 zotarolimus‐eluting stents (ZES) and 19 everolimus‐eluting stents (EES) as second‐generation DES. Cross‐sectional images of the bifurcation lesion using OCT were analyzed every 450 µm. All images were divided into three areas: inner wall of the bifurcation (IB), outer wall of the bifurcation (OB), and ostium of the side branch (SB). We compared the incidence of uncovered struts (IUS) among three areas and the averaged neointimal thickness (NIH) between IB and OB in each stent and also compared these OCT parameters among all DES. Results: There were no significant differences of IUS between IB and OB in second‐generation DES, while in first‐generation DES, IUS of IB and OB showed significant differences. The IUS of SES in both areas was significantly higher than in the other DES (all P < 0.001). PES had a significantly higher IUS in SB than the others (all P < 0.001). NIH of OB was significantly higher than that of IB in PES, ZES, and EES, but in SES the NIH was similar in the two areas. Conclusions: OCT revealed different neointimal growth patterns among SES, PES, ZES, and EES in bifurcation lesions. © 2014 Wiley Periodicals, Inc.     

Contradictory Shear Stress Distribution Prevents Restenosis after Provisional Stenting for Bifurcation Lesions

Background: Endothelial shear stress is one of the local hemodynamic factors suspected in the development of coronary atherosclerosis in bifurcation lesions. In patients with provisional stenting, the endothelial shear stress (SS) distribution is unknown. Objective: The aim of this study was to investigate the magnitude and distribution of the SS of coronary bifurcation lesions stenting by the provisional approach. Methods: Ten consecutive patients were included in this study. Quantitative coronary analysis, flow study, and three‐dimensional computational analysis with the aid of the commercial software CD STAR‐CCM+ were done before and after the provisional stenting procedure and also 8 months later. Results: Clinical and angiographic follow‐up were available in all patients. No patient had a side branch (SB) stent. At the 8‐month follow‐up, no major adverse cardiac event (MACE) occurred. There was also no clinical and angiographic restenosis. Before PCI, the distal main vessel (MV)‐lateral, and the SB‐lateral subsegments had relative nonsignificant lower SS value (4.08 ± 2.78 Pa and 4.35 ± 5.04 Pa, respectively) when compared to other segments. After 8‐month follow‐up, sustained decreased SS value was shown in the distal MV‐lateral segment (4.08 ± 2.78–1.68 ± 1.65 Pa), when compared with significantly increased SS value in the SB‐lateral subsegment 4.35 ± 5.04–16.50 ± 40.45 Pa). The explanation is that after stenting in the MV, the flow was redistributed immediately after percutaneous coronary intervention (PCI) and reversed back to its original 8 months later. However, the growth of the fibrous tissue causing in‐stent restenosis (ISR) is prohibited by sirolimus on the stent struts. In contrast, in a branch opened up by plain old balloon angioplasty (POBA), the flow did not change much, the flow could even be worse because it is shifted to the MV after the cross‐sectional area of the MV improved by stenting. However, thanks to POBA, there is increased fibrous tissue formation, enough to increase the SS and prevent further accumulation of cell and cholesterol needed for more restenosis. Conclusion: In the provisional approach, low endothelial SS correlated with no restenosis for patients who underwent stenting of the MV, while a contradictory combination of high SS and no restenosis was seen in the SB after only POBA. The mechanism of prevention of restenosis in the SB is by increasing the SS while in the MV, the mechanism of prevention of ISR is secondary to sirolimus on the stents struts. (J Interven Cardiol 2010;23:319–329)     

The Carina Angle—New Geometrical Parameter Associated with Periprocedural Side Branch Compromise and the Long‐Term Results in Coronary Bifurcation Lesions with Main Vessel Stenting Only

Background: The two main problems unresolved in coronary bifurcation stenting are periprocedural side branch compromise and higher restenosis at long term. The purpose of this study is to reveal the link between periprocedural side branch compromise and long‐term results after main vessel stenting only in coronary bifurcations. Methods: Eighty‐four patients formed the study population. The inclusion criteria were good‐quality angiograms, with maximal between‐branch angle opening, no overlap, permitting accurate angiographic analysis. Carina angle (α)—the distal angle between main vessel (MV) before bifurcation and side branch (SB)—was measured pre‐ and poststenting. Clinical follow‐up 9–12 months was obtained with coronary angiography if needed. Results: The patient population was high‐risk with 33% diabetics and 84% two‐ and three‐vessel disease. Ninety‐five stents were implanted in 92 lesions, with three T‐stenting cases. Drug‐eluting stents were implanted in 54%. Kissing‐balloon (KBI) or sequential inflation was performed in 35%. SB functional closure occurred in 17.4%, with independent predictors α < 40° and diameter ratio MB/SB >1.22. After 12±4 months there were five myocardial infarctions (6%) and 13 (15%) target lesion revascularization procedures. Independent predictors of major cardiovascular events were carina angle <40°, MB lesion length >8 mm, negative change of between‐branch angle, DES usage, and KBI. Conclusions: Smaller carina angle with straightening of MV—main branch from stent implantation in coronary bifurcations predicted higher SB compromise, restenosis, and MACE rates during follow‐up of 1 year.     

Comparison of Stent Expansion Guided by Optical Coherence Tomography Versus Intravascular Ultrasound: The ILUMIEN II Study (Observational Study of Optical Coherence Tomography [OCT] in Patients Undergoing Fractional Flow Reserve [FFR] and Percutaneous Coronary Intervention)

ObjectivesThe present study sought to determine whether optical coherence tomography (OCT) guidance results in a degree of stent expansion comparable to that with intravascular ultrasound (IVUS) guidance.BackgroundThe most important predictor of adverse outcomes (thrombosis and restenosis) after stent implantation with IVUS guidance is the degree of stent expansion achieved.MethodsWe compared the relative degree of stent expansion (defined as the minimal stent area divided by the mean of the proximal and distal reference lumen areas) after OCT-guided stenting in patients in the ILUMIEN (Observational Study of Optical Coherence Tomography [OCT] in Patients Undergoing Fractional Flow Reserve [FFR] and Percutaneous Coronary Intervention) (N = 354) and IVUS-guided stenting in patients in the ADAPT-DES (Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents) study (N = 586). Stent expansion was examined in all 940 patients in a covariate-adjusted analysis as well as in 286 propensity-matched pairs (total N = 572).ResultsIn the matched-pair analysis, the degree of stent expansion was not significantly different between OCT and IVUS guidance (median [first, third quartiles] = 72.8% [63.3, 81.3] vs. 70.6% [62.3, 78.8], respectively, p = 0.29). Similarly, after adjustment for baseline differences in the entire population, the degree of stent expansion was also not different between the 2 imaging modalities (p = 0.84). Although a higher prevalence of post-PCI stent malapposition, tissue protrusion, and edge dissections was detected by OCT, the rates of major malapposition, tissue protrusion, and dissections were similar after OCT- and IVUS-guided stenting.ConclusionsIn the present post-hoc analysis of 2 prospective studies, OCT and IVUS guidance resulted in a comparable degree of stent expansion. Randomized trials are warranted to compare the outcomes of OCT- and IVUS-guided coronary stent implantation.     

Relative dependence of diameters of branches in coronary bifurcations after stent implantation in main vessel--importance of carina position

BACKGROUND AND AIM: Bifurcation lesions are relatively frequently encountered in everyday interventional practice. Stenting of the vessel chosen to be main (usually the larger one) frequently leads to stenosis at the ostium of the side branch (SB) and compromises its flow (side branch compromise--SBC). The relative dependence of main and side branch diameters, based on the concept of carina displacement of stent struts, was examined in a cohort of patients with bifurcation stenting. METHODS: We accept that the basic mechanism for SBC after stent placement in the parent vessel is carina shifting from expanded stent struts. The ostial SB minimal lumen diameter (MLD), percentage diameter stenosis (%DS) at maximal and calculated actual carina displacement, as well as distal limb diameter (DLD) in the main branch were calculated and compared with actually observed values. RESULTS: A group of 55 consecutive patients with acceptable quality angiograms formed the study population. General patient characteristics were similar to other bifurcation studies. Left anterior descending artery was predominantly treated in 73% of patients. There was worsening SB ostial stenosis after stent implantation (%DS increase from 48%+/-23% to 69%+/-21%, p <0.001) and final improvement because of kissing balloon inflation or SB postdilatation (post vs. final-69+/-21% and 53+/-25%, p<0.001). Stent implantation causes straightening of the main vessel, evident from a significant increase in angle C (pre- 148 degrees +/-19 degrees vs. 156 degrees +/-16 degrees after stenting, p=0.007). Relations between observed and predicted values for main branch DLD and %DS demonstrated a good correlation between predicted and observed values (for DLD r=0.66, p<0.001, and for %DS r=0.53, p <0.001). There was an excellent fit of regression lines between theoretical predictions and actual measurements for side branches (MLD r=0.91, p<0.001, %DS r=0.89, p<0.001).CONCLUSIONS: Carina displacement from stent struts is a major mechanism governing changes in coronary bifurcations after main vessel stenting. Improvement in the ostium of the side branch causes shifting back of the carina and a decrease of main vessel diameter. The long-term consequences of this phenomenon are not currently known.     

Preintervention angiographic and intravascular ultrasound predictors for side branch compromise after a single-stent crossover technique

A single stent crossover technique is the most common approach to treating bifurcation lesions. In 90 bifurcation lesions with side branch (SB) angiographic diameter stenosis <75%, we assessed preintervention intravascular ultrasound (IVUS; of main branch [MB] and SB) predictors for SB compromise (fractional flow reserve [FFR] <0.80) after a single stent crossover. Minimal lumen area (MLA) was measured within each of 4 segments (MB just distal to the carina, polygon of confluence, MB just proximal to polygon of confluence, and SB ostium). All lesions showed Thrombolysis In Myocardial Infarction grade 3 flow in the SB after MB stenting. Although angiographic diameter stenosis at the SB ostium increased from 26 ± 15% before the procedure to 36 ± 21% after stenting (p = 0.001), FFR <0.80 was observed in only 16 patients (18%). Negative remodeling (remodeling index <1) was seen in 83 (92%) lesions but did not correlate with FFR after stenting. Independent predictors for FFR after stenting were maximal balloon pressure (p = 0.002) and MLA of SB ostium before percutaneous coronary intervention (p <0.001), MLA within the MB just distal to the carina (p = 0.025), and plaque burden at the SB ostium before percutaneous coronary intervention (p = 0.005), but not angiographic poststenting diameter stenosis or minimal lumen diameter. For prediction of FFR <0.80 after percutaneous coronary intervention, the best cutoff of MLA within the SB ostium before percutaneous coronary intervention was 2.4 mm(2) (sensitivity 94%, specificity 69%). Also, the cutoff of plaque burden within the SB ostium before percutaneous coronary intervention was ≥51% (sensitivity 75%, specificity 71%). In 67 lesions with an MLA ≥2.4 mm(2) or plaque burden <50% before percutaneous coronary intervention, 63 (94%) showed FFR ≥0.80. However, FFR <0.80 was seen in only 12 (52%) of 23 lesions with an MLA <2.4 mm(2) and plaque burden ≥50%. In conclusion, there do not appear to be reliable IVUS predictors of functional SB compromise after crossover stenting.     

Theoretical prediction of side branch compromise after main branch stenting in coronary bifurcation

One of the main problems of treatment of bifurcation lesions is side branch (SB) stenosis appearing after stent placement in the main vessel.The aim of this study was to create quantitative method for prediction of side branch compromise extent.We accepted that the main mechanism for SB ostial stenosis is flow divider (FD) displacement from stent struts after stent implantation in the main vessel.Using easily measurable parameters from coronary angiography,as SB diameter,angle α (initial angle between axes of parent vessel and SB axis) and angle α' (angle between above mentioned axes after stent placement) we can calculate percentage diameter stenosis at branch ostium (%DS):%DS = sin (α - α')/(tan α).In boundary condition of full FD displacement %DS = cos α.We tested our theoretical predictions with fluoroscopic observation of elastic wall model of bifurcation (45°distal angle between branches)permitting wall deformations with stent.There is full coincidence of values of %DS and percentage area stenosis (%AS).The regular formulas for calculations of %DS and %AS overestimate stenosis severity between 10% and 25%.Our model tests have shown full coincidence between predicted values for %DS and observed values.We demonstrate that part of the SB ostium is not visible in regular angiography and contributes to ostial lumen area.This is a method that permits quantitative prediction of side branch compromise.     

Optical coherence tomography analysis of the stent strut and prediction of resolved strut malapposition at 3 months after 2nd-generation drug-eluting stent implantation

Our objective was to clarify whether thrombogenic problems with stent struts are resolved at 3 months after 2nd-generation drug-eluting stent implantation. Twenty-one patients with stable angina pectoris having 28 (22 zotarolimus-eluting, 6 everolimus-eluting) stents with optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) were evaluated. Stent strut coverage and malapposition were evaluated by OCT immediately after PCI and at 3-month follow-up. Acute strut malapposition was observed in 26 out of 28 analyzed stents (92.9 %). At 3-month follow-up, 7 (26.9 %) of those 26 stents with strut malapposition were completely resolved, and the mean percentages of uncovered struts and malapposed struts were 8.3 and 2.0 % when analyzed by each individual stent. When analyzing a total of 30,060 struts, 807 struts (2.7 %) demonstrated acute strut malapposition. Among these, 219 struts (27.1 %) demonstrated persistent strut malapposition. On the basis of receiver-operating characteristic curve analysis, a strut-to-vessel (S-V) distance ≤160 µm on post-stenting OCT images was the corresponding cutoff point for resolved malapposed struts (sensitivity 78.1 %, specificity 62.8 %, area under the curve 0.758). The S-V distance of persistent malapposed struts on post-stenting OCT images was longer than that of resolved malapposed struts (235 ± 112 vs. 176 ± 93 µm, p < 0.01). At 3 months after PCI, the prevalence rates of uncovered and malapposed struts were relatively low in 2nd-generation drug-eluting stent. Our results suggest that OCT-guide PCI with an S-V distance ≤160 µm may be recommended especially in patients with planed short-term DAPT.     

Impact of Diabetes Mellitus on Intravascular Ultrasound‐Guided Provisional Stenting in Coronary Bifurcation Lesions J‐REVERSE Sub‐Study

Objective

To investigate the impact of diabetes mellitus (DM) on provisional coronary bifurcation stenting under the complete guidance of intravascular‐ultrasound (IVUS).

Background

The efficacy of such intervention has not yet been fully elucidated in the DM patients.

Methods

A total of 100 DM and 139 non‐DM patients in a prospective multi‐center registry of IVUS‐guided bifurcation stenting were compared in angiographic results at 9 months. Vessel and luminal changes during the intervention were analyzed using the IVUS. Vascular healing at the follow‐up was also investigated in 23 lesions in each group using optical coherence tomography (OCT).

Results

No difference was detected regarding baseline reference vessel diameter and minimum lumen diameter in proximal main vessel (MV), distal MV, and side branch (SB). The rate of everolimus‐eluting stent use (78.4% vs. 78.3%), final kissing inflation (60.1% vs. 49.0%), and conversion to 2‐stent strategy (2.9% vs. 2.8%) were also similar. In the DM group, late loss was greater in proximal MV (DM 0.23 ± 0.29 vs. non‐DM 0.16 ± 0.24 mm, P < 0.05) and SB (0.04 ± 0.49 vs. ?0.08 ± 0.35 mm, P < 0.05). Smaller vessel area restricted stent expansion in the proximal MV (6.18 ± 1.67 vs. 6.72 ± 2.07 mm², P < 0.05). More inhomogeneous neointimal coverage (unevenness score, 1.90 ± 0.33 vs. 1.72 ± 0.29, P < 0.05) and more frequent thrombus attachment (26% vs. 4%, P < 0.05) were documented in the proximal MV at 9‐month follow‐up OCT.

Conclusions

Despite IVUS optimization for coronary bifurcation, DM is potentially associated with smaller luminal gain, higher late‐loss, and inhomogeneous vascular healing with frequent thrombus attachment in the proximal MV.