Histopathologic and physiologic effect of bifurcation stenting: current status and future prospects

Introduction: Coronary bifurcation lesions are involved in up to 20% of all percutaneous coronary interventions (PCI). However, bifurcation lesion intervention is associated with a high complication rate, and optimal treatment of coronary bifurcation is an ongoing debate.Areas covered: Both different stenting techniques and a variety of devices have been suggested for bifurcation treatment, including the use of conventional coronary stents, bioresorbable vascular scaffolds (BVS), drug-eluting balloons (DEB), and stents dedicated to bifurcations. This review will summarize different therapeutic approaches with their advantages and shortcomings, with special emphasis on histopathologic and physiologic effects of each treatment strategy.Expert opinion: Histopathology and clinical data have shown that a more simple treatment strategy is beneficial in bifurcation lesions, achieving superior results. Bifurcation interventions through balloon angioplasty or placement of stents can importantly alter the bifurcation's geometry and accordingly modify local flow conditions. Computational fluid dynamics (CFD) studies have shown that the outcome of bifurcation interventions is governed by local hemodynamic shear conditions. Minimizing detrimental flow conditions as much as possible should be the ultimate strategy to achieve long-term success of bifurcation interventions.

The Tryton® dedicated bifurcation stent: Five-year clinical outcomes

AIMS

We report the first 5 year clinical follow-up data for the Tryton® bifurcation stent.

METHODS AND RESULTS

Clinical outcomes at five years were collected from 8 centres. Non-hierarchical Major Adverse Cardiovascular Events (MACE) and Major Adverse Cerebrovascular and Cardiovascular Events (MACCE) were collected. Diabetic and non-diabetic populations were compared, along with small (≤2.5 mm) vs large (>2.5 mm) side branch size. 173 patients with a follow up rate of 98% at 5 years were analysed. Non-hierarchical MACE was low at 9.8%, consisting of cardiac death of 1.2% (n = 2) and MI of 1.7% (n = 3). Target lesion revascularization (TLR) rate was 6.9% (n = 12). Non-hierarchical MACCE was also low, with major bleeding in 2.3% (n = 4) and strokes in 1.7% (n = 3) of patients. There was only 1 case (0.6%) of stent thrombosis that was definite and occurred very late (782 days). All-cause mortality was low, with 8.7% combined cardiac and non-cardiac death (n = 15). Diabetic patients had significantly higher event rates, but there was no difference in events with lesion stratification by side branch size.

CONCLUSIONS

The Tryton® Side-Branch Stent has a non-hierarchical MACE of 9.8% and MACCE of 13.9% at 5 years. The TLR was 6.9% with only 1 case of stent thrombosis recorded.

The Need For Dedicated Bifurcation Stents: A Critical Analysis

There is growing evidence that optimally performed two-stent techniques may provide similar or better results compared with the simple techniques for bifurcation lesions, with an observed trend towards improvements in clinical and/or angiographic outcomes with a two-stent strategy. Yet, provisional stenting remains the treatment of choice. Here, the author discusses the evidence - and controversies - concerning when and how to use complex techniques.

Comparison between two-dimensional and three-dimensional quantitative coronary angiography for the prediction of functional severity in true bifurcation lesions: Insights from the randomized DK-CRUSH II, III, and IV trials

OBJECTIVE

This study investigated the diagnostic accuracy of three-dimensional quantitative coronary angiography (3D-QCA) compared with conventional 2D-QCA for predicting functional severity assessed by fractional flow reserve (FFR) for true bifurcation lesions.

METHODS

Based on pooled data from the randomized DK-CRUSH II, III, and IV trials, we evaluated the patients with true bifurcation lesions who underwent coronary angiography together with functional evaluations using FFR in both the main vessel and the side branch. Off-line 2D- and 3D-QCA analyses were conducted using dedicated bifurcation QCA analysis software. Measurements of minimum lumen diameter (MLD), percentage diameter stenosis (% DS), and minimum lumen area (MLA) were compared between 2D- and 3D-QCA, and we evaluated their predictive values of functionally significant FFR.

RESULTS

Ninety patients were eligible for enrollment in the present study. In the main vessel, MLA measured by 3D-QCA was the most accurate predictor of FFR <0.75 (C statistic 0.85, P < 0.001), while MLD measured by 2D-QCA was a similarly accurate predictor (C statistic 0.85, P < 0.001). In the side branch, the best metrics for predicting FFR <0.75 were % DS measured by 2D-QCA with a C statistic value of 0.91 (P < 0.001) and MLA measured by 3D-QCA with a C statistic value of 0.81 (P < 0.001). However, both 2D- and 3D-QCA metrics exhibited low accuracies for predicting FFR <0.75 in intermediate bifurcation lesions.

CONCLUSIONS

3D-QCA analysis for true bifurcation lesions did not improve the predictive accuracy of functionally significant FFR compared with 2D-QCA analysis. In lesions with intermediate stenosis, the diagnostic performance of both 2D- and 3D-QCA-derived measurements in differentiating functional severity is limited.

Approach to Treatment of Bifurcation Lesions

OPINION STATEMENT

Bifurcation lesions are frequently encountered in the cath lab [1] and remain a challenge for conventional percutaneous coronary intervention (PCI) techniques. Although provisional stenting remains the default approach for most bifurcation lesions [2-6], the two-stent technique is more appropriate in certain situations. If a two-stent strategy is selected, then final kissing balloon inflation (KBI) should be performed. Adjunctive assessment with intravascular imaging (intravascular ultrasound (IVUS)/optical coherence tomography (OCT)) and physiologic testing (fractional flow reserve, FFR) should be performed liberally. Drug-eluting stents (DES) are typically utilized to reduce the risk of restenosis in bifurcation disease.

Clinical outcome of patients with de novo coronary bifurcation lesions treated with the Tryton Side Branch Stent. The SAFE-TRY prospective multicenter single arm study

BACKGROUND

Coronary bifurcation lesions represent a difficult problem regularly confronting interventional cardiologist, in part due to the lack of dedicated device.

OBJECTIVE

To investigate the feasibility, safety and effectiveness of the Tryton Side Branch Stent (Tryton Medical, Durham, NC, USA), a dedicated bare metal stent deployed in conjunction with a standard drug-eluting stent to treat bifurcation lesions.

METHODS

The SAFE-TRY is a prospective single arm multicenter registry including patients with de novo bifurcation lesions in native coronary arteries and syntax score <32. The primary endpoint was target vessel failure (TVF) at 30 days that comprised cardiac death, target vessel myocardial infarction and clinically driven target vessel revascularization. Secondary endpoints included device, angiographic and procedural success, 9-month major adverse cardiac and cerebrovascular event (MACCE), and stent thrombosis (ST) rates (ClinicalTrials.gov identifier: NCT01174433).

RESULTS

Among 252 enrolled patients, 24% had diabetes and 35.3% unstable angina. True bifurcation lesions involving both branches occurred in 96.8% of cases with Medina classification 1.1.1 in 62%. The left anterior descending artery and the left main were treated in 70% and 8.3% of the patients, respectively. A 6 Fr guide catheter was used in 61% of the cases. Device, angiographic and procedural success rates were 99.6%, 99.6% and 97.2% respectively. The 30-day TVF was 2.8%; the 9-month MACCE rate was 13.7%, with target lesion revascularization being 4.4%. No definite ST occurred.

CONCLUSIONS

This prospective, multicenter study confirmed the feasibility, safety and effectiveness of the Tryton Side Branch Stent to treat patients with de novo complex bifurcation lesions.

Double bifurcation lesion treated with double Tryton Sidebranch Stent: first case report

The optimal percutaneous treatment strategy for coronary bifurcation lesions is still unknown. Several dedicated coronary bifurcation stents, such as the Tryton Side Branch Stent™ (Tryton Medical, Durham, NC) have been developed to improve clinical outcomes. We presented a double bifurcation lesion case treated with two Tryton sidebranch stents, with a single drug eluting stent covering the main vessel and both bifurcations.

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.