Proximal to Distal Y-Stent Deployment for Coronary Bifurcation Lesions: Procedure and Three-Year Clinical Outcomes

Abstract

Aims. Percutaneous coronary intervention with Y-stenting of coronary bifurcation disease is not commonly undertaken. The procedural and medium-term clinical outcomes of coronary bifurcation lesions treated with the proximal to distal Y stent technique by a single experienced operator were reviewed. Methods. A total of 167 consecutive procedures using either provisional Y strategies or full-coverage options performed at Auckland City Hospital, New Zealand, between January 2013 and July 2018 were included in this retrospective observational study. All medical records and coronary angiograms were reviewed. Results. Three-year clinical follow-up data were available in 162 of 167 patients. The primary endpoint, defined as the composite of cardiovascular death, spontaneous myocardial infarction (MI), target-lesion revascularization (TLR), target-vessel nontarget-lesion revascularization (nontarget-lesion TVR), and stent thrombosis (ST) occurred in 25 patients (15%) at 3 years. Secondary endpoints were all-cause mortality (12%), including cardiovascular mortality (6%), noncardiovascular mortality (4%), undetermined death (2%), spontaneous MI (7%), TLR (1%), nontarget-lesion TVR (0%), and ST (0.6%). Conclusions. The proximal to distal Y-stent technique is a widely applicable approach to bifurcation lesions, with good medium-term clinical outcomes when used in a heterogeneous group of clinical and anatomical scenarios. Complications related to the stented site were infrequent. Randomized, controlled trials are needed to assess its efficacy compared with other bifurcation interventional techniques.

J INVASIVE CARDIOL 2022;34(5):E397-E407. Epub 2022 April 22.

Key words: bifurcation percutaneous coronary interventions, bifurcation technique, Y stent

Coronary bifurcation lesions can be technically challenging to treat, despite a number of available techniques. A single-stent strategy with provisional side-branch (SB) stenting is the mainstay of treatment for simpler bifurcation lesions. However, a single-stent strategy is less well suited to more complex disease, such as a bifurcation lesion with Medina 1,1,1 anatomy, an SB ≥2.5 mm in diameter, and disease extending beyond the SB ostium. Commonly used 2-stent strategies include T-stenting, culotte, and mini-crush techniques. Despite limited randomized trial data, there is current enthusiasm for the double-kissing crush approach,^1-4 although major adverse cardiovascular event (MACE) rates in these selected trial populations were reported at 5%-11.4% with 8-12 months of follow-up, which is much lower than real-world experiences^5-7 reporting MACE rates of 10.2%-21.8% at 2-5 years of follow-up.

The Proximal to Distal Y-Stent Technique

Y-stenting, also called the “skirt” technique, was initially described using a distal to proximal approach.⁸ It was revised by Helqvist et al in 2006,⁹ who reported a series of 30 bifurcation lesions treated in a proximal to distal (PD) sequence, which improved the coverage of the carina (Figure 1). The technique described herein has been further modified to be undertaken via the radial artery using a 6-Fr guide catheter, and with the option of a provisional Y-stent approach (Figure 1B). The steps of this technique are outlined as follows:

1. At baseline angiography, obtain 2 orthogonal views that clearly profile the bifurcation carina, without vessel foreshortening or overlap.

2. Wire both the main vessel (MV) and SB. Predilate the MV and SB lesions with balloon angioplasty, including kissing-balloon inflation, if necessary (Figure 2).

3. Position a stent, matched in diameter and length to the upstream vessel disease, with its distal end at the carina. Inject 2 mL of contrast. Review the angiogram frame by frame to confirm that the distal edge of the stent is exactly adjacent to the carina. Adjust the position and reinject contrast, as necessary. Once happy with the position, inflate the balloon to deploy the upstream MV stent (Figure 3). If the proximal MV stent was deployed too proximally, the procedure can still be completed with a slightly longer length in the metallic neocarina. However, if the position of the stent is too distal, ie, jailing the ostium of the SB, bail-out methods include conversion into a T-stent, reverse-crush, or culotte technique.

4. Using the jailed SB guidewire for guidance, advance a new guidewire through and out the distal lumen of the deployed MV stent into the SB, taking care not to catch a stent strut (Figure 4). Remove the jailed SB wire to avoid trapping and fracture of the distal tip. Postdilate the MV stent using a noncompliant balloon to ensure that the lesion and stent are fully expanded and the stent is optimally opposed to the vessel wall (Figure 5).

5. The next step depends upon the type of bifurcation lesion being treated.

a. Medina 1,0,0. The procedure either stops at this point, or the distal end of the stent can be flared to match the bifurcation shape, using 2 short balloons sized to the downstream MV and SB diameters, respectively. The balloons are positioned partly within and partly distal to the stent and inflated simultaneously at low pressure. This makes the distal end of the stent more oval shaped, and opposes the struts to the outer flanks of the bifurcation.

b. Medina 1,1,0 or 1,0,1. A stent with its diameter and length matched to the downstream MV/SB vessel and disease is positioned with its proximal edge abutting the upstream MV stent, and a noncompliant balloon is positioned in the SB or distal MV (Figure 6). Image-enhancement software, such as CLEARstent (Siemens) or StentBoost (Philips), is useful for ensuring exact positioning of the stent. The stent is deployed, the delivery balloon is withdrawn 1-2 mm, and kissing-balloon inflation is performed.

c. Medina 1,1,1. Two appropriately sized stents can be positioned in the downstream MV and SB, respectively, and deployed simultaneously (Figure 7). Both stent delivery balloons are then withdrawn 1-2 mm and postdilation is performed (Figure 8). With some stent types, 2 devices cannot be simultaneously advanced through a 6-Fr guide catheter. In those circumstances, a 7-Fr guide (or a 7.5-Fr sheathless guide catheter) can be used. Alternatively, 1 stent is deployed with a balloon in the other vessel, as for a provisional approach, followed by another stent and balloon, in the nonstented and stented vessels, respectively. This completes the full PD Y-stent technique using 3 stents (Figure 9).

Use of the PD Y-stent technique offers unique advantages, including flexibility with a wide range of bifurcation anatomy, and allows for a provisional strategy when sufficient. It is technically easier to perform than some of the other 2-stent strategies, with minimal stent strut distortion as there is no need to re-cross stent struts, and the SB is rewired through the distal lumen of the proximal MV stent. Both MV and SB access are maintained throughout the procedure. All 3 segments of the bifurcation can be sized separately and appropriately to lessen carina shift from oversized distal MV stent or postdilation balloon (Figure 10), which can lead to SB occlusion. Bail-out methods (see step 3 above) provide further flexibility to complete the procedure with full coverage of the carina. Despite these advantages, the technique has not become widely used or undergone evaluation in randomized trials. It does require deployment of an additional stent, although this has become less of a concern with lower drug-eluting stent costs. A cohort of consecutive patients treated with this technique in a real-world setting are reviewed herein to assess their medium-term clinical outcomes and provide insight into whether this is a feasible technique warranting comparison with other bifurcation techniques in randomized trials. The aim of this study is therefore to evaluate the medium-term clinical outcomes of consecutive patients undergoing provisional or full PD Y-stent deployment as the preferred bifurcation percutaneous coronary intervention (PCI) strategy by a single operator.

Methods

Study design. This is an audit of consecutive bifurcation PCI procedures using the Y-stent technique by an experienced PCI operator (MW) from a single center in Auckland, New Zealand. Table 1 outlines all procedures included in the study period. A bifurcation lesion was defined according to Lefèvre et al^10,11 with MV and SB diameters ≥2.5 mm and ≥2.0 mm, respectively, by visual estimation.

We reviewed medical records and coronary angiograms of all patients treated using a Y-stent technique between January 1, 2013 and July 5, 2018. The median follow-up period of 3 years was chosen to capture the majority of MACEs related to the bifurcation technique. Data collection was obtained through the public medical records of the 4 public hospitals (Auckland City Hospital, Middlemore Hospital, North Shore Hospital, and Whangarei Hospital) in the Northern region of New Zealand. All patients’ hospital admission notes, discharge summaries, coronary angiograms, and clinic letters under the Cardiology Services during the follow-up period were reviewed.

During the audit period, the operator undertook 1267 PCI procedures, of which 286 (23%) included the treatment of bifurcation lesions. The decision of bifurcation technique used was at the operator’s discretion, and was mostly dependent upon the coronary anatomy and clinical appropriateness, including hemodynamic status.

Of the bifurcation procedures, 84 (29%) used conventional provisional SB stenting; only 35(12%) procedures used other 2-stent strategies, such as T-stent, T and protrusion (TAP), or V-stent techniques. The remaining 167 procedures (58%) used the Y-stent technique and were included in this retrospective observational study. Ninety-six procedures used full Y stenting with 3 stents, while 50 and 21 procedures used provisional strategies with 1 and 2 stents, respectively (Table 1). The drug-eluting stents used were Promus Premier and Synergy (Boston Scientific), Xience Prime and Xience Xpedition (Abbott Vascular), and Resolute Onyx (Medtronic).

Study endpoints. The primary endpoint was MACE at a median of 3-year follow-up, defined as a composite of cardiovascular mortality, spontaneous myocardial infarction (MI), target-lesion revascularization (TLR), target-vessel nontarget-lesion revascularization (TVR), and probable or definite stent thrombosis (ST). Secondary endpoints were all-cause mortality and the individual components of the primary endpoint.

Definitions. Medina classification¹¹ was used to describe bifurcation anatomy in our study. The endpoint definitions were concordant with the 2018 consensus document by the Academic Research Consortium-2.¹²MI was defined as type 1 or 2 MI from the universal definition of MI proposed in 2012,¹³ with high-sensitivity troponin T increase to ≥3 times the upper limit of normal combined with clinical symptoms or ischemic electrocardiographic changes of MI. Stable angina patients included patients with Canadian Cardiovascular Society (CCS) I-III symptoms. Acute coronary syndrome patients included patients with non-Q-wave MI and unstable angina. In all patients who presented with ST-segment elevation MI (STEMI), the procedure was performed as primary PCI. Spontaneous MI is defined as further recurrent MI after discharge from the index procedure from a nontarget vessel. The target lesion is defined as the treated segment including the 5-mm margin proximal and distal to the stent. TLR was defined as repeat revascularization by PCI or coronary artery bypass graft (CABG) surgery of the target lesion. Nontarget-lesion TVR was defined as revascularization by PCI or CABG of any segment of the target vessel, excluding the target lesion. Definite ST is defined as angiographically documented acute thrombus that originates from 5 mm proximal or distal to the stent in the presence of acute ischemic symptoms, new ischemic electrocardiographic changes, or typical rise and fall in the high sensitivity troponin T. Probable ST is any MI that is related to documented acute ischemia in the territory of the implanted stent without angiographic confirmation and in the absence of any other obvious cause. Acute ST, subacute ST, late ST, and very late ST were defined as occurring within 24 hours, 30 days, 1 year, or >1 year from the index procedure, respectively.

In-stent restenosis was defined as ≥50% diameter stenosis. Renal disease was defined as serum creatinine ≥200 µmol/L or on any form of dialysis. Other comorbidities include any major cardiac diagnosis (eg, any form of cardiomyopathy) or chronic disease in another organ system that may potentially affect the patient’s survival. Cardiogenic shock is defined as systolic blood pressure persistently <90 mm Hg requiring inotropic and/or mechanical support.

Statistical methods. Analysis was performed using SAS, version 9.4 (SAS Institute Inc). Data for categorical variables are reported as frequency and percentage (%) and data for continuous variables are summarized using mean ± standard deviation. Kaplan-Meier curves were used to estimate freedom from MACE and Cox regression (univariate and multivariate stepwise) to estimate the hazard ratios (HRs). Confidence intervals (CIs) are presented with 95% degree of confidence. All statistical tests used a significance level of alpha=0.05. P-values ≤.05 were considered statistically significant.

Results

Baseline clinical, angiographic, and procedural data. Baseline demographic, clinical presentations and angiographic data are summarized in Table 2, Table 3, and Table 4, respectively. The majority of ­patients were male and of European ethnicity. Most procedures were performed on patients who presented acutely with an acute coronary syndrome (non-STEMI [49%] or STEMI [29%]) and who required primary PCI or semi-urgent inpatient procedures.

Many patients had poor left ventricular function or comorbidities such as chronic renal disease, which would have excluded them from randomized trials. There was good adherence to dual-antiplatelet therapy, mostly a combination of aspirin and ticagrelor (given for 12 months) in those with acute coronary syndromes or aspirin and clopidogrel (given for 6 months) in those with stable angina.

Of the 167 procedures performed, the majority (95%) were performed via radial artery access using 6-Fr sheath. Femoral access was generally reserved for patients on renal dialysis, graft cases, failed radial access, and in those in cardiogenic shock without a palpable radial pulse.

Angiographically, the majority of the bifurcation procedures were performed on true Medina 1,1,1 lesions (n = 120; 72%), followed by 1,1,0 lesions. This corresponds with 96 procedures using full PD Y-stent and 50 procedures using provisional 2-stent PD Y-stent strategies. Long lesion length, presence of calcification requiring rotational atherectomy, and a small number of procedures performed on chronic total occlusions suggest complex coronary anatomy with high-risk features.

A small number of procedures included the deployment of ≥3 stents due to either distal or proximal edge dissections or extensive disease that required further additional upstream or downstream stents.

Almost all patients (166/167) had angiographic procedural success, ie, Thrombolysis in Myocardial Infarction 3 flow in both the MV and SB, and without any significant residual stenosis (no more than 20%) in the MV. Three procedures (2%) had evidence of residual stenosis in the SB at the end of the index procedure. There was 1 procedure-related complication in this study, which was a radial artery dissection that was managed conservatively without any significant clinical consequence.

Of note, 1 procedure comprised bail-out Y-stenting of the left main bifurcation to treat extensive left coronary artery dissection propagating from a ruptured postdilation balloon in the left circumflex artery, which was the culprit vessel in a patient with STEMI. Despite angiographic and procedural success, the patient died from multiorgan failure after an extended stay in the cardiac intensive care unit.

The mean procedural time was 79.2 minutes, with a mean fluoroscopy time of 25.6 minutes. This included 49 procedures (29%) involving another nonbifurcation lesion and 9 procedures (5%) that included a second bifurcation lesion.

Clinical outcome. Of the 167 procedures performed, 162 had follow-up data available with a median follow-up period of 3.0 ± 0.8 years. The cumulative event rate for the primary endpoint of MACE (composite of cardiovascular death, spontaneous MI, stroke, TLR, nontarget-lesion TVR, probable or definite ST) is shown in Figure 11 and Table 5. At 3 years of clinical follow-up, 25 patients (15%) had a MACE. The MACE rates were 3% (n = 5) and 7% (n = 11) at 1-year and 2-year follow-up, respectively. The MACE rate was mostly driven by cardiac death and spontaneous MI. The TLR rate (1%), nontarget-lesion TVR rate (0%), and ST rate (0.6%) were all low. The only incident of ST was in a patient who stopped dual-antiplatelet therapy 2 weeks post procedure, apparently due to drug side effects from both clopidogrel and ticagrelor.

All-cause mortality was 12% at 3 years (Table 5). Cardiovascular death occurred in 3 patients whose initial presentation was STEMI with cardiogenic shock, and who subsequently developed multiorgan failure. The other cardiovascular deaths were due to further community cardiac arrest (n = 1), non-ST-segment elevation MI (n = 3), chronic end-stage heart failure (n = 2), and subacute ST (n = 1). There were also noncardiovascular (n = 6; 4%) and undetermined deaths (n = 3; 2%). Four patients with noncardiovascular death had metastatic malignancies, while 2 patients died of infection (pancreatitis and necrotizing fasciitis, respectively) at 6 months and 2 years after the index procedure. Common features of those dying of undetermined causes were older age (69-84 years) and the presence of comorbidities, such as chronic hepatitis C, previous stroke, poor left ventricular function, and history of ventricular tachycardia that required implantable cardioverter-defibrillator. In the 3 patients with deaths of undetermined cause, the index presentation in 2 patients was STEMI, 1 of whom was in cardiogenic shock. The deaths occurred at 7, 9, and 12 months after the index procedure, respectively. Two of the 3 patients had been treated with a provisional Y-stent strategy.

There were 12 spontaneous MIs unrelated to the Y-stenting (ie, separate from TLR or nontarget-lesion TVR) in this patient cohort (median age, 63 ± 9.8 years). Most presented acutely with either non-STEMI (n = 5) or STEMI (n = 3); 7 of these patients had diabetes. Most (n = 11) had full Y-stent deployment at their index procedure, while 1 patient had a 2-stent provisional strategy. Three patients had untreated residual disease. They also had comorbidities such as renal disease (n = 2) or other comorbidities, as defined earlier. In 3 patients, the left ventricular ejection fraction was <40%.

Twenty-one of the 162 patients had repeat coronary angiogram for various reasons (Table 6). Most of the repeat angiograms were performed in the context of further non-STEMI; 1 patient was specifically brought back for angiographic follow-up due to presentation with inferior STEMI while already on dual-antiplatelet therapy (aspirin and clopidogrel). Fifteen of the 21 patients showed no evidence of restenosis in any of the MV/SB segments treated with Y-stenting. The remaining 6 procedures showed subacute ST in 1 patient, as previously mentioned; 2 procedures showed severe in-stent restenosis involving the neocarina and MV stents which required coronary artery bypass grafting, as previously mentioned. Three procedures showed moderate in-stent restenosis involving the ostium of the SB and were managed medically.

Stroke occurred in 3 patients who were 64 years old, 78 years old, and 85 years old at 7 months, 9 months, and 18 months post index procedure, respectively. Two had a previous stroke and 1 had poor left ventricular function with a left ventricular ejection fraction <40%.

Two patients who were 46 years old and 79 years old had TLR by surgical revascularization at 6 months after the index procedure. The younger patient had pre-existing moderate left main stem disease during the index procedure, which had progressed to become severe on the repeat angiogram as well as moderate in-stent restenosis at the ostium of the SB, which was in an obtuse marginal branch. The older patient had Y-stent deployment to the left anterior descending and diagonal disease. Repeat angiography showed severe in-stent restenosis at the neocarina as well as moderate in-stent restenosis in the mid-distal MV stent. Both procedures were performed on smaller-caliber vessels, with the MVs measuring 2.8 mm and 2.7 mm and the SBs measuring 2.4 mm and 2.1 mm, respectively. There was no other target-vessel or nontarget-lesion revascularization undertaken.

Comparing full Y-stenting (n = 96) vs provisional Y-stenting (n = 66), MACE rates were 22% and 8%, respectively, at 3 years (Figure 12).

In multivariate analysis using patient groups with MACE vs those without MACE (Table 7), the independent predictors were age (HR, 1.10; 95% CI, 1.06-1.15; P<.001), prior CABG (HR, 3.74; 95% CI, 1.17-11.98; P=.03), left ventricular ejection fraction <40% (HR, 13.10; 95% CI, 4.88-35.14; P<.001), and presence of cardiogenic shock (HR, 27.87; 95% CI, 5.83-133.17; P<.001).

Discussion

This study represents a single-operator, all-comers experience with Y-stent deployment used as the preferred multiple-stent strategy for complex bifurcation PCI, in addition to its frequent use in a provisional approach. There was a high procedural success rate, and stent-related complications were relatively infrequent during follow-up to 3 years. Over three-quarters of the study population had presented with an acute coronary syndrome, and over one-quarter were undergoing primary PCI for STEMI, reflecting the patient population undergoing PCI at Auckland City Hospital. Many had features of increased risk, including a significant proportion who were older, with other comorbidities, significant left ventricular systolic impairment, or who had complex coronary anatomy. There was a high disease burden in this study, as 5% of procedures involved another bifurcation lesion and 29% had another lesion treated during the same procedure. Patients in cardiogenic shock were included. Overall, this cohort represents a higher-risk group of patients, including many who would have been excluded from randomized trials and some registries of bifurcation PCI. The median follow-up of 3 years is long enough to capture most events related to the Y-stent procedure.

Although first described over 20 years ago, Y-stenting has not become widely used, and has not been compared in randomized trials with other multiple-stent approaches for bifurcation PCI. It is adaptable to a wide range of bifurcation anatomy and lesion distribution, and has a provisional option. Compared with other techniques, advancing balloons and undeployed stents out the end of a stent is easier than between stent struts, and, once deployed, there is less stent distortion. However, this technique does require meticulous attention to stent positioning prior to deployment. It is unsuitable for patients in whom the bifurcation carina cannot be fully profiled, those in whom there is marked stent oscillation during positioning, and those in whom available stent lengths don’t match the vascular anatomy, eg, very short left main coronary arteries.

An initial upstream vessel stenting approach is also undertaken with the Axxess self-expanding coronary stent (Biosensors). Although the medium-term outcomes reported in the DIVERGE study¹⁴ were encouraging, there are technical challenges with accurately and consistently deploying the stent close to the carina, which has led to it not being widely used.

As reported in other series, outcomes were better in those treated with a provisional approach than those requiring stenting of both downstream branches. Although some believe that this supports using a provisional approach whenever possible, with branch vessel stenting only for bail-out, the disease substrate is different in “true” bifurcation lesions. While outcomes may depend upon which stenting strategy is employed, they are also likely to depend upon how well the chosen strategy is performed.

The procedural data show that the procedure can be readily undertaken using a 6-Fr guide catheter via the radial artery access in most patients. Matching the stent size to each vessel segment and having a balloon inflated to low pressure in the SB may lessen the tendency for the carina to shift and for the SB to occlude when a provisional approach is used. This may also be facilitated by avoiding the need to cross stent struts when rewiring the SB, and minimizing strut distortion especially when the angle between distal branches was <70°. Although care is needed with exact stent positioning, the technical difficulty of the procedure is less than that of some of other techniques, such as the double-kissing crush technique.

The strong predictors of outcome in multivariate analyses, especially poor left ventricular function and cardiogenic shock, were likely to be significant irrespective of the bifurcation technique used, as they are predictors of mortality in coronary artery disease.

Of note, the TLR rate (1%) and nontarget-lesion TVR rate (0%) are low in this study, while other studies report TLR of 3.8%-4.3% and TVR of 2.9%-18.3% depending on the length of follow-up.^1-6,15

Clinical implications and strengths. The results of this observational study on a complex cohort of patients, including those with high-risk features who are usually excluded from randomized trials, have given insight into the clinically driven outcomes following PD Y-stenting strategy in an everyday setting. This is a flexible technique with a number of unique advantages and should be considered as a feasible alternative option to other contemporary bifurcation PCI approaches.

Study limitations. The main limitation of this study is the retrospective nature of the audit. MACE may have occurred in some of the 5 patients lost to follow-up. Intravascular imaging was undertaken in only a few patients, and there was no routine angiographic follow-up, so the angiographic restenosis rate is unknown. With regard to clinical follow-up, a few patients may have moved out of the region or presented to a private hospital (although in New Zealand these do not provide acute care). It is possible that not all patients who re-presented with MI had a repeat coronary angiogram to assess the target lesion. The clinical decisions were usually made with consideration of relative contraindications and lack of clinical benefit for those individuals. The small number of undetermined deaths might also be device related, although there is no feasible way of finding out. Asymptomatic target-lesion disease will not be captured in this cohort as endpoints were clinically driven.

This study represents the experience of a single PCI operator from a single center. As with other bifurcation techniques, there is an initial learning curve to become familiar with the technique and to achieve the optimal procedural result and patient outcome. Deployment of an additional stent adds cost to the procedure, although this is becoming less of an issue with decreasing drug-eluting stent prices.

Conclusion

This retrospective, observational study describes procedural and 3-year clinical outcomes on the largest cohort of consecutive, unselected patient treated with the Y-stent technique. Y-stenting is not widely used, and lacks evaluation in randomized trials. However, it is a technique that is feasible and applicable to a wide range of bifurcation anatomy and clinical scenarios, including use in a provisional strategy. The MACE rate in this all-comers patient cohort is acceptable. The technique provides an alternative option to conventional bifurcation approaches. Further data, including randomized comparisons with those techniques, are needed.

Affiliations and Disclosures

From ¹Auckland City Hospital, Auckland, New Zealand; ²Queen Elizabeth Hospital, Birmingham, United Kingdom; ³Intra Healthcare, Auckland, New Zealand; ⁴Ascot Cardiology Group, Auckland, New Zealand.

Funding: Dr Ding reports research fellowship funding from the Green Lane Research and Education Fund.

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 accepted July 8, 2021.

Address for correspondence: Patricia Y.J. Ding, MB ChB, Cardiology Department, Level 3, Building 32, 2 Park Road, Grafton, Auckland 1010, New Zealand. Email: patriciading@hotmail.com

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