Optical coherence tomography assessment of a new dedicated bifurcation stent

OCT-guided Percutaneous Coronary Intervention in Bifurcation Lesions

Coronary artery bifurcation lesions remain challenging despite significant advancements in stent technology and development of specific bifurcation stenting approaches. Optical coherence tomography (OCT) is the intracoronary imaging technique with the highest resolution and can generate automatically contoured lumen areas across the variable geometry of bifurcation lesions. Knowledge of plaque severity and composition facilitates planning of the best strategy for percutaneous coronary intervention (PCI) and stenting. In particular, the provisional stent strategy preferred in this context can be modified when there is high risk of side-branch compromise at the ostium after main vessel stenting. OCT is unique because it allows the identification of the site of guide wire crossing, an important determinant of the final result. OCT can also be used to assess the procedural success of new dedicated bifurcation stent technologies and for the evaluation at follow-up of potential predictors of stent thrombosis, including stent malapposition, stent under-expansion and stent-edge dissection. Finally, the development of 3D OCT allows a better evaluation of coronary anatomy — particularly of side branch ostium that is difficult to visualise by 2D OCT — further improving the value of this technique in guiding PCI in these patients.

Optical coherence tomography to guide percutaneous treatment of coronary bifurcation disease

INTRODUCTION

Cardiovascular disease remains the most common cause of death worldwide. Enormous progress in the technology and applicability of percutaneous techniques to treat obstructive coronary heart disease has been made, and the number of percutaneous coronary interventions (PCI) is increasing. Coronary bifurcations are involved in a substantial number of PCIs and despite recent advances, bifurcation PCI remains a challenge in terms of immediate success and long-term outcome. Angiography has a limited capacity for showing important features of the 3 dimensional coronary vessel anatomy, position of stent struts and exact wire positions and is therefore suboptimal for guiding bifurcation PCI. Intracoronary optical coherence tomography (OCT) provides high resolution and the information gained during PCI is unprecedented compared with angiography guidance and intravascular ultrasound. Areas covered: This review will provide an overview of the use of OCT to guide bifurcation-PCI. Expert commentary: OCT is a promising guide for bifurcation-PCI at each individual step: from planning the strategy (provisional versus two-stent strategy), to guidance during PCI, and finally checking the interventional result. Until dedicated randomized trails are complete, we recommend OCT guidance for interventions in complex coronary bifurcation disease and for imaging when unexpected procedural events occur.

Difference of neointimal growth patterns in bifurcation lesions among four kinds of drug-eluting stents: an optical coherence tomographic study

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.

Frequency-domain optical coherence tomography findings in patients with bifurcated lesions undergoing provisional stenting

AIMS

Bifurcations represent challenging lesions which may benefit from improved understanding of stent-related vessel complications. Since optical coherence tomography (OCT) allows us to detect post-stenting vessel injuries, we sought to assess the geographic pattern of stent-related complications occurring during provisional stenting of bifurcated lesions.

METHODS AND RESULTS

Fifty-one patients with bifurcated lesions treated by provisional stenting and undergoing intra-procedural OCT assessment were enrolled. OCT images were acquired with the aim of guiding the percutaneous coronary intervention but were re-analysed off-line for the present study. The stented bifurcation was divided into four segments [three in the main vessel (MV) and one in the side branch (SB)]. The following acute post-stenting vessel injuries/complications at the different bifurcation segments were evaluated: (i) stent under-expansion, (ii) stent malapposition, (iii) stent edge dissection, (iv) side-branch ostium dissection, (v) tissue prolapse, (vi) intracoronary thrombus, and (vii) in-stent dissection. A total of 55 bifurcation lesions undergoing provisional stenting were analysed. At least one OCT complication was detectable in all cases. Across different bifurcation sites, significant differences in the occurrence of stent complications were observed. In particular, stent malapposition was more common at the proximal MV segment (P < 0.001), while tissue prolapse was more common at the distal MV segment (P < 0.001).

CONCLUSION

In bifurcated interventions, OCT often detects vessel injuries/stent complications, which tend to have a specific geographical distribution. In particular, stent malapposition is more common at the proximal MV and tissue prolapse at the distal MV segment.

Placement of Tryton Side Branch Stent only; a new treatment strategy for Medina 0,0,1 coronary bifurcation lesions

OBJECTIVES

We propose a new treatment strategy of Medina 0,0,1 bifurcation lesions using a dedicated side branch stent alone (Tryton Side Branch Stent™) without additional main branch stenting, with the advantage of an optimal ostial side branch coverage without the disadvantage of an excessive amount of metal in the main branch.

BACKGROUND

Medina 0,0,1 lesions are relatively rare and there is no consensus on treatment strategy. Several previous techniques have been described, all with considerable disadvantages.

METHODS

Between October 2009 and November 2011, 12 patients with Medina 0,0,1 lesions treated with Tryton alone were included. Clinical outcomes were reported as all-cause mortality, recurrent myocardial infarction (MI), target vessel revascularization (TVR), target lesion revascularization (TLR), and target vessel failure (TVF; defined as the composite of all-cause mortality, MI, and TVR). Procedural success was defined as successful stent placement with residual stenosis <30%, postprocedural TIMI 3 flow, and no in-hospital TVF.

RESULTS

Mean age was 64 years. Median side branch reference vessel diameter was 2.6 [2.5-3.0] mm (median stenosis 75%). Procedural success was 100%. Median clinical follow-up duration was 868 [470-906] days with just one of the patients suffering from a late adverse clinical outcome: TLR at 427 days, resulting in TVF, TVR, and TLR rates of 8.3%.

CONCLUSION

Treatment of Medina 0,0,1 lesions with the Tryton stent alone was associated with a 100% procedural success and only one late clinical adverse event (median follow-up of 868 days). These first positive results need to be confirmed in larger prospective randomized studies.

New strategies in the treatment of coronary bifurcations

Despite major improvements in stent technology (i.e., drug-eluting stents, DES), treatment of coronary bifurcations is an ever occurring problem of the interventional cardiology. While stenting the main branch with provisional side branch stenting seems to be the prevailing approach, in the era of DES various two-stent techniques emerged (crush) or were re-introduced (V or simultaneous kissing stents, crush, T, culottes, etc.) to allow stenting in the side branch when needed. New techniques in imaging like optical coherence tomography help in better understanding bifurcation anatomy and, thus, have the potential to help us better treat this challenging subset of lesions. In addition, new dedicated bifurcation stents have been proposed in an attempt to overcome limitations associated with current approaches, and they showed promising results in early studies; however, the safety and the efficacy of these devices remain to be seen in the ongoing and upcoming trials. This review focuses on the current approaches and the development of new techniques employed for the treatment of bifurcation disease.

Final proximal post-dilatation is necessary after kissing balloon in bifurcation stenting

AIMS

High rates of restenosis and stent thrombosis are still often observed after bifurcation stenting despite the recommended stent post-dilatation using the kissing balloon (KB) technique. We investigated the potential benefits of a final post-dilatation step in bifurcation stenting with a balloon that respects the natural diameter ratio of the proximal and distal vessels in bifurcations (Murray's law).

METHODS AND RESULTS

Fourteen commercially available stents (Xience V, Taxus Liberté and Presillion) were deployed in a silicone model of a coronary bifurcation using a provisional stenting approach. After side branch (SB) ostium dilatation and KB inflation, stent geometry and strut apposition was analysed using micro-CT. A final proximal inflation step was then performed to post-dilate only the proximal segment of the main vessel (MV). KB inflation produces an asymmetrical dilatation of the stent in the proximal part of the bifurcation with a number of struts left malapposed in the MV. Using the proposed final proximal inflation (FPI) step reduces the average stent eccentricity index from 0.72 to 0.90 (p<0.001) and the percentage of malapposed struts in the proximal part of the MV from 33.4% to 0.6% (p=0.02), while increasing the minimum stent area from 6.8 mm² to 8.5 mm² (p < 0.0001).

CONCLUSIONS

A final dilatation of the stent only in the MV proximal to the SB with a balloon sized according to the mother vessel is suggested to prevent stent malapposition and optimise stent deployment in bifurcation stenting.

Simple versus complex approaches to treating coronary bifurcation lesions: direct assessment of stent strut apposition by optical coherence tomography

INTRODUCTION AND OBJECTIVES

Stenting of coronary bifurcation lesions carries an increased risk of stent deformation and malapposition. Anatomical and pathological observations indicate that the high stent thrombosis rate in bifurcations is due to malapposition of stent struts.

METHODS

Strut apposition was assessed with optical coherence tomography (OCT) in bifurcation lesions treated either using the simple technique of stent implantation in the main vessel only or a complex technique (i.e. Culotte's). A strut was regarded as malapposed if the gap between its endoluminal surface and the vessel wall was greater than its thickness plus an OCT resolution error margin of 15 microm.

RESULTS

Simple and complex (i.e. Culotte's) approaches were used in 17 and 14 patients, respectively. Strut malapposition was significantly more frequent for the half of the bifurcation on same side as the vessel side branch (median, 46.1%; interquartile range [IQR], 35.3-62.5%) than for the half opposite the side branch (9.1%; IQR, 2.2-21.6%), the distal segment (7.5%; IQR, 2.3-20.2%) or the proximal segment (12.6%; IQR, 7.8-23.1%; P< .0001); the gap between strut and vessel wall in malapposed struts was significantly greater in the first segment than the others: 98 microm (IQR, 37-297 microm) vs. 31 microm (IQR, 13-74 microm), 49 microm (IQR, 20-100 microm) and 38 microm (IQR, 17-90 microm), respectively (P< .0001). Using the complex technique had no effect on the prevalence of strut malapposition in the four segments relative to the simple technique (P=.31) but was associated with a smaller gap in the proximal segment (47 microm vs. 60 microm; P=.0008).

CONCLUSIONS

In coronary bifurcation lesions, strut malapposition occurred most frequently and was most significant close to the side branch ostium. The use of Culotte's technique did not significantly increase the prevalence of strut malapposition compared with a simple technique.