Innovative Provisional Stenting Approach to Treat Coronary Bifurcation Lesions: Balloon-Stent Kissing Technique

Abstract: Background. Adverse cardiac event rates are higher for percutaneous coronary intervention (PCI) of bifurcation lesions. Currently, provisional stenting or a simple stenting strategy is the standard treatment for bifurcated lesions, but its performance remains limited because of a risk of side-branch (SB) closure and a higher rate of target lesion revascularization (TLR). We report a new provisional side-branch stenting strategy to treat coronary bifurcation lesions using a “balloon-stent kissing” technique (BSKT). Methods. From January 2011 to December 2012, a total of 60 patients with 60 bifurcation lesions underwent PCI using BSKT. Baseline and postprocedural quantitative coronary angiography (QCA) analyses were performed. Procedural and immediate clinical outcomes were reviewed. Results. The majority of patients presented with acute coronary syndrome (98%) and had true bifurcation lesions (98%). TIMI-3 flow was established in 100% of the main branch and SB lesions. QCA revealed preservation of the bifurcation angle after PCI (pre PCI, 57.0 ± 16.3; post PCI, 60.5 ± 16.1; P=.24). Five patients (8%) had lesions that required rewiring and 2 patients (3%) required provisional stenting of the SB. No SB loss occurred during PCI. No patient had a periprocedural myocardial infarction, nor was the balloon or wire entrapped during any PCI. Conclusions. As a new coronary bifurcation provisional stenting method, the BSKT is associated with a high procedural success rate, improved SB patency, and a low rate of immediate cardiac events.

J INVASIVE CARDIOL 2013;25(11):600-604

Key words: percutaneous coronary intervention, bifurcation lesion, provisional stenting approach

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Coronary bifurcation management with current technologies is still a long way from an optimal solution; coronary bifurcation lesions comprise 15%-20% of percutaneous coronary interventions (PCIs).^1,2 PCI of coronary bifurcation lesions is associated with technical difficulty, a low rate of procedural success, and a high rate of adverse cardiovascular outcomes, including periprocedural myocardial infarction (MI), target lesion revascularization (TLR), and stent thrombosis.^3-5 Several studies have concluded that stenting the main branch (MB) with provisional side-branch (SB) stenting is preferable in the great majority of bifurcation lesions.^6-8 Provisional SB stenting is the technique of using a stent for the MB, and stenting the SB only if necessary. However, stenting of the SB may be required in up to 51% of bifurcation lesion PCIs.⁵ MB stenting can cause plaque shift, spasms, changes in the bifurcation angle, and/or SB ostial conformational changes including total occlusion, which makes PCI of the SB technically challenging. A previous study has suggested that permanent SB compromise occurred in 16% of patients, and was associated with an increased risk of large periprocedural MI and renal failure among unselected patients with major bifurcation lesions undergoing a “simple” stenting approach.⁹ Thus, the challenges of bifurcation PCI are associated with preservation of both the MB and SB, and reduced rates of periprocedural complications and TLR.

We set up, and bench tested, a novel technique for SB protection using a balloon-stent kissing technique (BSKT): an inflating balloon with suitable pressure in the SB during MB stent deployment; namely, the SB balloon is first inflated to a suitable pressure, then the MB stent is immediately deployed to nominal pressure. The inflated SB balloon serves to prevent both carina and plaque shifts due to its SB ostium spatial occupation during MB stent deployment.

Methods

Study population. At our institution, a total of 1048 patients underwent PCI between January 2011 and December 2012. A retrospective analysis identified 126 patients who underwent PCI of de novo coronary bifurcation lesions with a visually estimated diameter stenosis >50% involving the MB at or within 10 mm of the origin of an SB. Of the 126 patients, a total of 60 patients with 60 distinct coronary bifurcation lesions underwent PCI using BSKT. BSKT was first used at our institution in January 2011. Baseline patient characteristics were obtained through a review of the medical records. Each coronary bifurcation lesion was classified according to the Movahed classification system using visual estimation of each coronary angiogram.¹⁰ Each patient provided informed written consent for the procedure. Retrospective data collection was approved by our local Institution Review Board.

Procedural Technique 

All patients received aspirin (300 mg) and a loading dose of clopidogrel (300-600 mg) prior to or at the time of PCI. All patients received anticoagulation during the procedure; however, the agent, dosage, duration, and the addition of glycoprotein IIb/IIIa inhibitors were left to the operator’s discretion. Following PCI, all patients received aspirin 100 mg daily (indefinitely), and clopidogrel 75 mg daily for at least 1 year.

The decision to use the BSKT for PCI of a coronary bifurcation lesion was based on operator discretion. In general, patients selected for stenting using the BSKT had significant SB ostial disease, difficult bifurcation angles, and/or anatomy and lesion morphology that would make SB access difficult. For the procedure, 6-7 Fr coronary guiding catheters were used via a transfemoral or transradial approach to allow for monorail stent/monorail balloon or over-the-wire stent/monorail balloon combinations. The SBKT is a standardized technique that is used independently at our institution and is detailed in Figure 1 and shown angiographically in Figure 2: (1) both limbs of the bifurcation are accessed with standard 0.014˝ coronary guidewires, typically using short 180 cm wires in the MB and SB; (2) predilatation of the MB is performed with a standard Ryujin balloon; (3) a standard coronary stent is then advanced into the correct position over the lesion in the MB, while a monorail balloon that is angiographically sized to approximate the SB vessel diameter (generally 1.5-2.5 mm and of adequate length) is advanced into the SB, and SB predilatation is performed (Figures 2B-2C); (4) removal of MB stent proximad covers the lesion and SB balloon proximum, and finally the proximal marker of the SB balloon is positioned approximately 2 mm to the stent proximum to prevent entrapment, and with adequate balloon length to project distally into the SB beyond its ostium; (5) the SB balloon is first inflated to suitable pressure (6-10 atm), then the MB stent is immediately deployed to nominal pressure (Figure 2D), and then the stent balloon and SB balloon are deflated simultaneously; (6) if the SB has not been compromised (ie, TIMI-3 flow), then the trapped SB balloon and wire are removed. However, if there is less than TIMI-3 flow in the SB, routine balloon angioplasty is performed before the balloon and wire are removed. The SB wire may be left in place at the discretion of the operator and removed after MB stent optimization (as illustrated in steps 7 and 8); (7) the MB stent balloon’s position is maintained carefully during SB wire/balloon removal; (8) the stent balloon is then fully expanded to moderate or high pressure as clinically indicated for the optimization of the MB stent apposition, and to correct any stent deformation as a result of the SB balloon inflation (Figure 2E). If the wire has been left in the SB, it is removed at this time; (8) final angiography will then reveal whether or not re-crossing through the stent struts into the SB is necessary for provisional angioplasty and/or stenting (Figure 2F). The use of intravascular ultrasound (IVUS) following PCI, as well as any further intervention based on IVUS findings, is based solely on the operator’s judgment.

Following PCI, patients were monitored for postprocedural complications. Creatine kinase MB (CK-MB) was measured in all patients at least twice 6-8 hours post intervention.

Quantitative coronary angiography. Quantitative coronary angiography (QCA) analysis was performed by a single investigator unaware of the patent’s clinical outcome, using offline analysis of DICOM-formatted cine acquisition images using SIE-ADS V3¹ image processing software (Siemens) for measurement of the bifurcation angle, reference vessel diameter (RVD), minimal luminal diameter (MLD), and percent diameter stenosis before and after intervention.

Procedural and clinical outcomes. Procedural outcomes for each index PCI were independently reviewed by an author who was not an operator in the case. TIMI flow grading was established for the MB and SB for each patient. Each angiogram was reviewed for any procedural complications, including coronary dissection, SB loss or intervention, balloon rupture or entrapment, and IVUS findings. Periprocedural MI was defined in non-acute coronary syndrome patients as at least one CK-MB elevation of more than three times the upper reference limit, or in ACS patients as a ≥20% increase in elevation following stable or declining CK-MB levels, according to the guidelines set forth by the Academic Research Consortium.¹¹ 

Statistical analysis. Categorical variables are presented as numbers and percentages. Continuous variables are presented as mean ± standard deviation. The continuous variables for the QCA analysis were compared before and after PCI using the T-test or Mann-Whitney U-test. Results were considered significant if P<.05. Statistical analysis was performed using SPSS version 17.0.

Results

Baseline clinical characteristics for the 60 patients in the study are shown in Table 1. The majority of patients were male (72%), with a high prevalence of risk factors for coronary artery disease (CAD). The majority of patients (98%) presented with acute coronary syndromes and 13% of patients had undergone prior PCI. All patients were discharged following PCI with at least dual-antiplatelet therapy (ie, aspirin and clopidogrel).

The bifurcation lesion and stenting characteristics are shown in Table 2. The majority of lesions (98%) are true bifurcation lesions, and more than half of the patients (63%) had bifurcation lesions affecting the left anterior descending and a diagonal branch. The mean number of stents placed was 1.1 ± 0.3, and 90% were drug-eluting stents. Only 2 lesions (3%) required SB stenting. IVUS was used in 82% of PCIs of bifurcation lesions using BSKT (n = 49). No stent strut fracture or deformation was noted, and 84% of lesions had evidence of well-apposed stent(s) without any complications from PCI. Based on the IVUS findings, 16% of lesions (n = 8) characterized by IVUS required further intervention. 

QCA analysis for the MB, SB, and bifurcation angle are shown in Table 3, whereas immediate procedural and clinical outcomes are listed in Table 4. The MLD improved in the MB and SB following PCI without a significant change in the bifurcation angle. Following MB stent re-expansion (Figure 1, step 7), a total of 5 SB lesions were re-crossed with a wire based on operator discretion; 2 of these SB lesions underwent stenting, and the remaining lesions underwent balloon angioplasty. One patient underwent SB stenting due to TIMI-2 flow in the SB, whereas the other patient underwent SB stenting due to concern for plaque shift. Mean post-PCI SB diameter stenosis was 29.0 ± 16.7%, 7 patients had an SB diameter stenosis ≥50% following PCI, and as mention earlier, the only 2 patients in this group who underwent SB stenting did so because of TIMI-2 flow or plaque shift in the SB. Side-branch closure did not occur in any patient after MB stent optimization following removal of the SB balloon. TIMI-3 flow was established in all but 2 of the MB vessels; 2 cases of MB coronary edge dissection were observed. All MB coronary dissections were treated with additional stenting. One dissection occurred at the proximal edge of the MB stent after MB stent deployment, unrelated to inflating or removing the SB balloon. The remaining edge dissection occurred at the distal end of the MB stent. No SB dissection or occlusion was observed. No patient had a periprocedural MI. The SB balloon or wire was not entrapped or ruptured in any case.

Discussion

The BSKT is a novel technique aimed at improving SB protection during provisional stenting of bifurcated lesions considered at high risk of SB compromise after MB stenting. The immediate procedural and clinical outcomes of the present study demonstrated that BSKT provided a high procedural success rate, with reliable preservation of SB patency for PCI of complex coronary bifurcation lesions. The population of the study presented with ACS (98%) with true bifurcation lesions (98%), which have relatively high clinical and angiographic risk. Thus, BSKT was successfully used in patients undergoing PCI of complex bifurcation lesions in both the emergent or elective clinical setting.

The treatment of bifurcation lesions can be technically challenging and is associated with a lower procedural success rate and a higher complication rate compared to non-bifurcated lesions.^12,13 The best approach to manage a bifurcation to achieve optimal procedural outcomes and long-term clinical success is still a matter of debate. To date, randomized studies have failed to demonstrate any clinical benefit of a complex strategy of systematic double stenting using drug-eluting stents, over the simple strategy of stenting the MB with provisional stenting of the SB.^8,14 Thus, the provisional stenting approach has emerged as a preferred choice when feasible, but has also been associated with a significant risk of SB compromise and periprocedural MI.^8,9 In cases of SB compromise, the first step is to pass a guidewire into the SB lumen through the MB stent struts. If this step is successfully achieved, balloon angioplasty and, if necessary, additional stenting of the SB will be performed. However, obtaining access to the SB with a guidewire can sometimes be challenging or even impossible, especially in the case of a dissection of the SB lumen. Strategies are needed to reduce the high rate of adverse events in PCI of bifurcation lesions.

The BSKT is a new modified provisional stenting technique that should reduce major adverse cardiac events. “Jailed” wire in the SB has been associated with reducing TLR.¹⁵ A recent study reported the JBT approach, where a non-inflated balloon was jailed in the SB during MB stenting to improve immediate clinical outcomes in bifurcation lesions.¹⁶ The technique is an extension of the “jailed” wire or balloon technique, and has been used at our institution since January 2011. Patients selected for stenting using the BSKT had SB bifurcation anatomy and lesion morphology that would make SB access difficult. In our study, the SB balloon was removed in all patients without damage or entrapment. In the patients who underwent IVUS, SBKT did not lead to any MB stent strut fractures or stent deformation.

The BSKT is designed to maximize SB patency. The majority of patients in our study had significant SB disease. Previous studies have found that SB occlusion is significantly associated with ostial or near-ostial SB disease, and plaque shift during MB stenting is the likely mechanism leading to SB occlusion.^17,18 Other predictors of SB occlusion are smaller SB diameter, SB origin within an MB lesion, and sharper bifurcation angles.¹⁹ In this study, inflating a balloon to a suitable pressure is used to avoid any plaque shift and loss of access to the SB that occurred during MB stenting. We observed that re-expansion of the MB stent balloon after removing the SB balloon did not cause significant plaque shift. Based on operator discretion, a total of 5 patients underwent re-crossing of the SB after MB stenting, of which 3 patients received rescue kissing balloon inflation and 2 patients were stented. In our study, the use of BSKT resulted in TIMI-3 flow in the SB in 100% of patients after PCI. We speculate that improved rates of SB patency should result in improved long-term clinical outcomes.

The bifurcation angle plays a critical role in selection of the stenting technique used for PCI of bifurcations lesions.² A registry analysis of 133 patients who underwent crush stenting of bifurcation lesions suggested that an angle ≥50° was an independent risk factor for major adverse cardiac events, which may provide a nidus for restenosis or possibly thrombosis.²⁰ The average pre-PCI bifurcation angle in our study was 57.0 ± 16.3°, thus possibly representing a group of patients with a higher risk of cardiac events. The pre-PCI bifurcation angle did not significantly change following stenting with the BSKT, thus preventing significant carina shift. Maintenance of the bifurcation angle may also be important, since any conformational change to the angle or carina could lead to SB occlusion or carina shift. In the present study, a stable bifurcation angle may have also contributed to the high rate of procedural success. 

Conclusion

The BSKT, a novel provisional side-branch stenting approach, provides a high rate of procedural success, improved SB patency, and a low rate of immediate cardiac events for complex coronary bifurcations lesions. In our study, BSKT was associated with a very low rate of SB occlusion and a very low rate of stenting of the SB. The BSKT will be an important modification to consider with provisional stenting of coronary bifurcation lesions. The BSKT can reduce the need for SB stenting and has the potential to improve long-term clinical outcomes. Further study is warranted to evaluate the role of BSKT in improving long-term clinical outcomes in PCI of complex bifurcation lesions. 

Acknowledgments.We thank Jian Zhang and Ailin Song for technical assistance. 

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From the Department of Cardiology, the Affiliated Zhongshan Hospital of Dalian
University, Dalian, China.

Funding: This work was supported in part by National Natural Science Foundation
of China, No. 81170187 (to Dr Li).

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure
of Potential Conflicts of Interest. The authors report no conflicts of interest
regarding the content herein.

Manuscript submitted May 28, 2013, provisional acceptance given July 8, 2013,
final version accepted July 29, 2013.

Address for correspondence: Longhu Li, MD, PhD, Department of Cardiology, the
Affiliated Zhongshan Hospital of Dalian University, 6 Jiefang Road, Zhongshan, Dalian
116001, China. Email: lilonghu75@hotmail.com