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Dedicated Bifurcation Paclitaxel‐Eluting Stent BiOSS Expert. W ... stem (LMS) stenosis treatment with dedicated bifurcation paclitaxel‐eluting stent BiOSS Expert.
© 2014, Wiley Periodicals, Inc. DOI: 10.1111/joic.12119

CORONARY ARTERY DISEASE Dedicated Bifurcation Paclitaxel‐Eluting Stent BiOSS ExpertW in the Treatment of Distal Left Main Stem Stenosis JACEK BIL, M.D., P H .D., 1 ROBERT J. GIL, M.D., P H .D., 1,2 DOBRIN VASSILEV, M.D., P H .D., 3 JAROSŁAW RZEZAK, M.D., P H .D., 1 TOMASZ KULAWIK, M.D., P H .D., 1 and TOMASZ PAWLOWSKI, M.D., P H .D. 1 From the 1Department of Invasive Cardiology, Central Clinical Hospital of the Ministry of Interior, Warsaw, Poland; 2Institute of Experimental and Clinical Medicine, Polish Academy of Science, Warsaw, Poland; and 3National Heart Hospital, Sofia, Bulgaria

Objectives: The aim of this study was to assess prospectively the effectiveness and safety profile of distal left main stem (LMS) stenosis treatment with dedicated bifurcation paclitaxel‐eluting stent BiOSS Expert1. Background: Angioplasty of distal LMS stenosis is always a high‐risk procedure, and optimal treatment is uncertain. Methods: This was a prospective international 2‐center study, which enrolled patients with non‐ST‐elevation acute coronary syndrome (NSTE‐ACS) or stable angina with distal left main stenosis. All patients were treated with the dedicated bifurcation stent BiOSS Expert1. Provisional T‐stenting was the obligatory strategy. Angiographic control was performed after 12 months. The primary end‐point was cumulative rate of death, myocardial infarction (MI), and target lesion revascularization (TLR) at 12 months. Angiographic end‐points included late lumen loss, percent diameter stenosis, and binary restenosis rate. Results: A total of 54 patients with distal LMS stenosis were enrolled. Seven patients (13%) were enrolled during NSTE‐ACS, 77.8% were hypertensive, 27.8% were diabetic, 51.9% had previous MI, 53.7% underwent prior percutaneous coronary intervention, and 16.7% coronary artery bypass graft. The mean SYNTAX score was 21.52  6.50. The device success rate was 100%. The mean BiOSS Expert stent parameters were as follows: 4.07  0.26 mm  3.36  0.26 mm  16.61  1.72 mm and in side branch the other stent (classical drug‐eluting stent) was implanted in 25.9% of cases. The overall TLR was 9.3%. There were no death, stent thrombosis, or acute MI. In the univariate regression analysis, the only factor associated with higher risk for TLR was the SYNTAX score value. Conclusions: The dedicated bifurcation stent BiOSS Expert1 proved to be a feasible device, with promising safety and long‐term clinical effectiveness in the treatment of distal LMS stenosis. (J Interven Cardiol 2014;27:242–251)

Introduction Although current guidelines still recommend coronary artery bypass graft (CABG) as a standard procedure for the treatment of unprotected left main significant stenosis, within the last decade a large body of evidence was gathered from registries and randomized trials supporting feasibility, efficacy, and safety of Address for reprints: Jacek Bil, Department of Invasive Cardiology, Central Clinical Hospital of the Ministry of Interior, 137 Woloska Street, 02‐507 Warsaw, Poland. Fax: (48) 225081177; e‐mail: [email protected]

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percutaneous coronary interventions (PCIs) in appropriately selected patients.1,2 Moreover, 2 recent meta‐ analyses showed that the primary end‐point of 1‐year major adverse cardiac and cerebrovascular events was nonsignificantly different in PCI group compared to CABG one, 14.5% versus 11.8%, P ¼ 0.11 and 14.49% versus 12.04%, P ¼ 0.15, respectively.3,4 In most cases, atherosclerosis develops in a distal part of left main stem (LMS) within the bifurcation or trifurcation.5 The predominant mechanism of side branch compromise after LMS/LAD/LCx cross‐over stenting is secondary to carina shift.6 And what must be underlined is the fact that this complex is a “special bifurcation” often with

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big differences in diameter. In order to decrease the risk of carina shift, BiOSS Expert1 stent (Balton, Warsaw, Poland) was developed.7 The main aim of this study was to assess prospectively the effectiveness and safety profile of the distal LMS stenosis treatment with dedicated bifurcation paclitaxel‐eluting stent BiOSS Expert1. The secondary aim was to test the significance of vessel diameter on late clinical outcomes after PCI treatment with the study device.

Methods Study Population. Between January and December 2011, patients with stable coronary artery disease or non‐ST‐elevation acute coronary syndrome (NSTE‐ ACS) qualified by Heart Team for PCI were enrolled in the study. Implantations were performed in 2 centers (Sofia, Bulgaria and Warsaw, Poland). Main inclusion criteria were serum creatinine level 4.0 mm. The primary end‐point was the rate of MACE including death, myocardial infarction (MI) with or without ST‐segment elevation, or need for repeated revascularization of the target lesion (TLR). The secondary end‐points included device success and periprocedural safety (periprocedural myonecrosis and complications). All deaths were deemed cardiac unless proved otherwise. Interventional Procedure and Concomitant Medications. BiOSS Expert1 is a coronary, dedicated bifurcation, balloon‐expandable stent made of 316L stainless steel (strut thickness of 120 mm) covered with a biodegradable polymer and paclitaxel (1 mg/mm2). The process of polymer biodegradation lasts approximately 8 weeks. The stent consists of 2 parts, proximal and distal, joined with 2 connection

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Figure 1. (A) BiOSS1 Expert stent, (B) BiOSS1 Expert stent on inflated Bottle1 balloon. Note the different sizes and lengths of 2 parts.

struts (depending on size: 0.9–1.5 mm) at the step‐up middle zone. The proximal part of the stent has a larger diameter in relation to the distal part (diameter ratio of proximal to distal parts: 1.15–1.3 mm)7 (Figs. 1 and 2). The stent was available in the following nominal parameters: proximal diameter: 3.25–4.5 mm; distal diameter: 2.5–3.75 mm; and length: 15–23 mm. Single stent implantation in the main vessel–main branch across a side branch was the default strategy in all patients (provisional T‐stenting, PTS). Stent implantation in LMS‐LAD or LMS‐LCx was left to the operator’s decision according to the plaque distribution and vessel diameters. Bifurcation lesions were assessed according to Medina classification using an index of 1 for stenosis greater than 50% and 0 for no stenosis (visual estimation).8 There was no restriction regarding lesion length in patient selection. If required, additional paclitaxel‐eluting stent (LucChopin2) was implanted. A stent in a side branch was implanted only if there was proximal residual stenosis greater than 70% after balloon dilatation and/or significant flow impairment after main vessel–main branch stenting and/or a flow‐ limiting dissection. Device success was defined as successful deployment of the intended stent without system failure. Angiographic success was assessed as the end‐procedural main branch diameter stenosis (DS) less than 20% and side branch ostial stenosis less than 70% without significant dissection and flow impairment. Procedure success included angiographic success in the absence of in‐hospital MACE (excluding asymptomatic TnI level increase).

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Figure 2. (A) Angiographic view before stent implantation, (B) BiOSS1 Expert stent implantation, (C) angiographic view after stent implantation, (D) IVUS analysis—proximal stent struts, (E) IVUS analysis—carina with stent struts and a wide access to the side branch, (F) IVUS analysis—distal stent struts.

The implantation protocol was as follows: 1. LAD and LCx wiring; 2. main vessel predilatation and/or side branch predilatation according to the operator’s decision; 3. stent implantation (inflation for at least 20 seconds); proximal optimization technique at operator’s discretion; 4. side branch postdilatation/side branch stent implantation if necessary; and 5. final kissing balloon inflation at operator’s discretion. In patients with ACS, loading dose of clopidogrel (600 mg) was given, and if needed, also the loading dose of acetylsalicylic acid (ASA) was applied (300 mg). In planned procedures, 72 hours before PCI each patient received ASA (75 mg/24 hours) and clopidogrel (75 mg/24 hours). All procedures were performed in a standard way via radial or femoral access using 6 or 7 Fr guiding catheters. After insertion of the arterial sheath, each patient received unfractionated heparin (100 IU/kg). Additional bolus was given to maintain an activated clotting time >250 seconds.

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DAPT (ASA 75 mg q.d. and clopidogrel 75 mg q.d.) was prescribed for 12 months. All patients had TnI, CK, and CK‐MB levels examined before the procedure and 24 hours after. Periprocedural MI was defined as troponin I and/or CK‐MB elevation more than 3 times above the upper normal limit (patients with NSTEMI were excluded from this assessment).9 Angiographic Analysis. All angiograms were recorded after intracoronary administration of 200 mg of nitroglycerin. Two orthogonal views were chosen to visualize the target lesion. A quantitative angiographic analysis was performed using Medis QCA version 5.0 (Leiden, the Netherlands). Catheter calibration was performed in all cases. The main vessel (the artery before side branch take‐off), the main branch (artery beyond the ostium of side branch), and the side branch (the smaller vessel at the point of vessel divergence) were analyzed separately—subsegmental QCA analysis was performed according to European Bifurcation Club Consensus.10 The following parameters were calculated: lesion length, reference vessel diameter (RVD), minimal lumen diameter (MLD), %DS, acute lumen gain (ALG), and late lumen loss (LLL) before and after stent implantation and/or on follow‐up. All

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reference diameters were measured 5 mm from the end of angiographically visible plaque in all three segments of bifurcation without use of interpolations (user defined reference diameters). Percent diameter stenosis (using parameters from each segment) was measured for each vessel segment separately using the following formula: %DS ¼ (1  [MLD/RVD])  100%. Angle A was defined as the distal bifurcation angle between the main branch and side branch axes, and angle a was defined as modified against vessel axis distal bifurcation angle, between the parallel line to the main vessel, passing through carina and side branch main axis.11 Statistical Analysis. Continuous variables were presented as mean  SD. Categorical data were presented as numbers (%). Continuous variables were compared using an unpaired Student’s t‐test, and categorical data using the x2 test or Fisher’s exact test, as appropriate. If distribution was not normal, Wilcoxon signed‐rank tests and Mann–Whitney U‐tests were used. P‐values of 4.0 mm, n ¼ 36, N (%)

65.6  11.5 10 (18.5%) 47 (87%) 7 (13%) 42 (77.8%) 38 (70.4%) 15 (27.8%) 28 (51.9%) 29 (53.7%) 9 (16.7%) 2 (3.7%) 5 (9.3%) 9 (16.7%) 21.52  6.58 3.85  3.50% 3.06  2.99%

70.7  8.9 0 17 (94.4%) 1 (5.6%) 16 (88.9%) 12 (66.7%) 5 (27.8%) 6 (33.3%) 7 (38.9%) 1 (5.6%) 0 3 (16.7%) 5 (27.8%) 23.3  6 3.96  4.20% 3.18  3.18%

63.0  11.9 10 (27.8%) 30 (83.3%) 6 (16.7%) 26 (72.2%) 26 (72.2%) 10 (27.8%) 22 (61.1%) 22 (61.1%) 8 (22.2%) 2 (5.6%) 2 (5.6%) 4 (11.1%) 20.6  6.8 3.80  3.20% 3.01  2.98%



Significant difference between Groups I and II, P < 0.01. CAD, coronary artery disease; UA/NSTEMI, unstable angina/non‐ST elevated myocardial infarction; MI, myocardial infarction; PCI, percutaneous coronary intervention; CABG, coronary artery bypass graft; AO, arteritis obliterans; CKD, chronic kidney disease.

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Figure 3. Medina classification: (A) whole group; (B) subgroup with LMS f  4 mm; (C) subgroup with LMS f > 4 mm. Table 2. Procedural Characteristics

Lesion type A B1 B2 C Successful implantation MV predilatation SB predilatation Both branches predilatation Nominal stent diameter in MV (mm) Nominal stent diameter in MB (mm) Nominal stent length (mm) Maximal pressure (atm) SB postdilatation FKB Additional stent in SB Fluoroscopy time (min) Contrast volume (ml) Vascular access femoral/radial Guiding catheter 6F/7F 

Whole Group, n ¼ 54, N (%)

BiOSS Ø  4.0 mm, n ¼ 18, N (%)

BiOSS Ø > 4.0 mm, n ¼ 36, N (%)

0 20 (37%) 29 (53.7%) 5 (9.3%) 100% 28 (51.9%) 13 (24.1%) 12 (22.2%) 4.07  0.26 3.36  0.26 16.61  1.72 15.4 34 (63%) 36 (66.7%) 14 (25.9%) 22.2  11.4 189.1  71.2 37%/63% 85.2%/14.8%

0 6 (33.3%) 10 (55.6%) 2 (11.1%) 100% 12 (66.7%) 7 (38.9%) 6 (33.3%) 3.72  0.08 3.01  0.06 16.83  1.50 14.9 10 (55.6%) 10 (55.6%) 4 (22.2%) 22.7  15.2 207  94 44.4%/55.6% 66.7%/33.3%

0 14 (38.9%) 19 (52.8%) 3 (8.3%) 100% 16 (44.4%) 6 (16.7%) 6 (16.7%) 4.25  0.00 3.53  0.08 16.50  1.86 15.8 24 (66.7%) 26 (72.2%) 10 (27.8%) 22.2  9.4 180  57 33.3%/66.7% 94.4%/5.6%

Significant difference between Group I and II, P < 0.01. MV, main vessel; MB, main branch; SB, side branch; FKB, final kissing balloon.

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Poststenting

Main vessel MV—RVD (mm) 4.15  0.32 4.23  0.33 MV—%DS 56  26% 6  5% Main branch MB—RVD (mm) 3.24  0.33 3.37  0.28 MB—%DS 43.4  26.0% 4  7% MB lesion length 5.4  2.9 Side branch SB—RVD (mm) 2.8  0.6 2.76  0.61 SB—%DS 28  31% 11  14% SB lesion length 2.5  3.7 Angle alpha (degrees) 55  22 52  22 Angle A (degrees) 79  47 72  46

FU 4.12  0.22 11.1  14.4% 3.21  0.43 14.2  19.4% 2.73  0.45 16.4  17.2% 56  19 77  51



Significant difference between prestenting and poststenting, P < 0.01. MV, main vessel; MB, main branch; SB, side branch; RVD, reference vessel diameter; %DS, % diameter stenosis; FU, follow‐up.

rates were 100%. Mean BiOSS Expert1 stent nominal parameters were as follows: 4.07  0.26 mm (proximal diameter)  3.36  0.26 mm (distal diameter)  16.61  1.72 mm (length). The mean maximal implantation pressure was 15.4  2.5 atm. The main branch was predilated in 51.9% of cases. The rate of proximal optimization technique was 16.6%, whereas the rate of final kissing balloon was 66.7%. The necessity to implant

the other stent in a side branch was in 25.9% of cases. Procedure details did not differ significantly between groups, except for stent proximal and distal diameters, which were significantly larger in Group II, 3.72  0.08 mm versus 4.25  0.00 mm (P ¼ 0.002) and 3.01  0.06 mm versus 3.53  0.08 mm (P ¼ 0.003), respectively. Angiographic data are presented in Tables 3 and 4. The immediate angiographic success rate was 100%. The quantitative angiography analysis revealed that BiOSS Expert1 implantation caused a significant increase of MLD and decrease of %DS in main vessel and main branch. However, this procedure did not affect angle alpha between proximal main vessel and side branch. All patients were followed up and all agreed to have control angiography after 12 months (mean 9.49  2.60 months), except for 1 patient in whom the episode of unstable angina appeared after 6.5 months. The detailed restenosis pattern is presented in Table 5. Overall TLR was 9.3%: in Group I—3 cases (16.7%) and in Group II—2 cases (5.6%). Three patients underwent repeated PCI (1 plain old balloon angioplasty [POBA], 1 drug‐eluting stent [DES] in the Group I, 1 DES in the Group II), whereas 2 patients were referred for CABG (1 in each group). There was no death, stroke, or in‐stent thrombosis (Table 6). Figure 4A and B shows changes in the ALG and the LLL in 3 bifurcation segments. There was much more net lumen gain in the main vessel and main branch in cases where BiOSS Expert1 stents with smaller

Table 4. Angiographic Parameters—Subgroup Analysis BiOSS Ø  4.0 mm, n ¼ 18

Main vessel MV—RVD (mm) MV—%DS Main branch MB—RVD (mm) MB—%DS Side branch SB—RVD (mm) SB—%DS Stent/artery ratio Angle alpha (degrees) Angle A (degrees)

BiOSS Ø > 4.0 mm, n ¼ 36

Prestenting

Poststenting

FU

3.81  0.21 56  23%

3.83  0.23 7  7%

3.14  0.30 55  19% 2.63  0.56 32  25% 54  22 76  34

Prestenting

Poststenting

FU

3.81  0.33 14.0  16.3%

4.33  0.20 57  29%

4.43  0.16 4.9  4.1%

4.44  0.19 9.6  13.5%

3.18  0.23 7  11%

3.23  0.13 11.6  18.5%

3.28  0.35 37.2  27.6%

3.46  0.27 2.8  4.0%

3.46  0.15 15.4  20.4%

2.61  0.54 16  15% 1: 1.15 52  22 68  31

2.51  0.44 20.6  25.2%

2.89  0.12 27  34%

2.84  0.64 9  13% 1: 1.19 52  24 75  54

2.91  0.56 14.3  11.5%

52  19 70  29

57  22 80  55

59  23 83  49



P < 0.01 for prevalues.  P < 0.01 for postvalues.  P < 0.01 for values post and FU. MV, main vessel; MB, main branch; SB, side branch; RVD, reference vessel diameter; %DS, % diameter stenosis; FU, follow‐up.

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BIL, ET AL. Table 5. Restenosis Pattern Localization No. 1. 2. 3. 4. 5.

Time (Month)

Type

MV

MB

SB

6.5 11 12 13 10.5

Focal Diffuse Focal Focal Focal

    

þ þ þ þ þ

þ    

TLR Clinically driven Angiographically Angiographically Angiographically Angiographically

Treatment

driven driven driven driven

CABG CABG POBA DES POBA

MV, main vessel; MB, main branch; SB, side branch; TLR, target lesion revascularization; CABG, coronary artery bypass graft; POBA, plain old balloon angioplasty; DES, drug‐eluting stent.

Table 6. Clinical Results 30 Days

n Death MI Stroke ST TVR TLR

6 Months

12 Months

All

I Gr

II Gr

All

I Gr

II Gr

All

I Gr

II Gr

54 0 8 (14.8%) 0 0 0 0

18 0 3 (16.7%) 0 0 0 0

36 0 5 (13.9%) 0 0 0 0

54 0 0 0 0 0 0

18 0 0 0 0 0 0

36 0 0 0 0 0 0

54 0 0 0 0 0 5 (9.3%)

18 0 0 0 0 0 3 (16.7%)

36 0 0 0 0 0 2 (5.6%)

 Asymptomatic increase in TnI concentration. All, whole group; I Gr, BiOSS Ø  4.0 mm; II Gr, BiOSS Ø > 4.0 mm; MI, myocardial infarction; ST, stent thrombosis; TLR, target lesion revascularization; TVR, target vessel revascularization.

diameters were implanted. The LLL values significantly differed between subgroups in the main vessel and the main branch (bigger in BiOSS Expert1 stents with smaller diameters), but not in the side branch. Finally, in the univariate regression analysis, the only factor associated with higher risk for TLR was the value of SYNTAX score.

Discussion The continuous advancement of angioplasty procedures broadens the range of lesions which could be safely treated with PCI. Bifurcation stenosis in distal LMS is one such case, whose rate is systematically increasing in the population of patients subjected to PCI.12 Our study showed a high rate of device success with favorable acute and long‐term clinical results expressed by MACE rate at 12 months. Additionally, the final procedural success rate proved that the stent

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had friendly profile in complex lesions. After BiOSS Expert1 stent implantation (during which the main vessel segment was straighten), the proximal and the distal main vessel segments returned to their initial position/angulation, opening the side of the stent to the branch, that is window (defined as the segment at the level of side branch inflow, Fig. 2). In our previous article, mean window length—the largest diameter within the window, was similar at baseline, but at postprocedure in BiOSS group it was significantly longer comparing to conventional DES group (2.21  0.37 vs 1.76  0.52 mm, P ¼ 0.01).13 Also, this stent provoked much less carina displacement, since it mimics the exact bifurcation construction with the proximal–distal main vessel diameter mismatch. These changes resulted in proximal and distal parts adequate configuration, matching vessel exact sizes.7,13,14 As a result there was relatively low rate of stent implantation in the side branch (25.9% of cases). In other studies, this value differed between

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Figure 4. (A) Acute lumen gain, (B) late lumen loss.  Significant difference between subgroups LMS f  4 mm versus LMS > f 4 mm. MV, main vessel; MB, main branch; SB, side branch.

30% and 50%.15–17 Moreover, there were no difficulties with rewiring the side branch, which also confirmed the hypothesis that BiOSS Expert1 stent suited well to PTS strategy.13 Also, the device success rate of BiOSS Expert1 stent was superior to other given implantation success rates for dedicated bifurcation stents,15,17–21 also in PCI within LMS stenosis.16 This might be the result of lack of issues, such as guidewires criss‐crossing, improper device orientation, or larger device profiles. Moreover, in other studies,

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there were higher rates of predilatation as well as postdilatation.15,17–21 In turn, high rate (66.7%) of final kissing balloon technique was associated with the belief in importance of this bifurcation and increased side branch stenting, where final kissing balloon technique was mandatory. In our opinion, the relatively high rate (8 cases, 15.1%) of periprocedural MI found in the study was, on one hand, associated with the complexity of procedures but, on the other, also on the admitted definition.9

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However, it must be stressed that after the procedure no patient had clinical symptoms of ischemia or significant ECG changes and there was no need for control angiography. Moreover, if we applied the third universal definition of the MI there would be only 5 cases (9.4%) of periprocedural MI. During the follow‐ up period there was no death, MI, or in‐stent thrombosis. Therefore, only TLR accounted for the primary end‐point. Restenosis was found in 5 patients, and TLR rate in the whole population was 9.3% (4 cases of angiographically driven TLR and 1 case of clinically driven TLR). This rate was comparable to other studies with values within the range of 6.6– 12%.16,17,19–21 In the article by Onuma et al., where TLR was the lowest (6.6%), it should be underlined that the study population was small (n ¼ 30) and less diseased (less diabetic, less hypertensive, and less prior MI). In our study, population was severely diseased, with the rate of diabetes (27.8%), prior MI (51.9%), prior PCI (53.7%), and prior CABG (16.7%) higher than in other comparable studies, respectively, 11– 25.7%, 19.5–46%, 11.3–37.1%, and 3.3–19%.15,17–21 Also, the complexity of lesions was higher (SYNTAX score 21.52  6.58) than in other trials.16 Worth mentioning is the fact that in the original article of Serruys et al.,22 12‐month cumulative rate of MACE in population of patients with low SYNTAX score (0–22) was 14.7% and with intermediate SYNTAX score (23– 32), 16.7%. However, in that article, TLR was mainly driven by clinical symptoms. Additionally, there is the well‐known fact that angiography doubles TLR rate.23,24 Therefore, we can assume that in our study the clinically driven TLR could be much lower (around 4.0%). In fact, there was only 1 case of clinically driven TLR (1.8%). Once we analyzed the data after the division of the study population into 2 subgroups (according to the stent diameter), it was disclosed that in the group with stent diameter of >4.0 mm TLR rate was 5.6% and in the subgroup with stent diameter 4.0 mm, 16.7%. Although nonsignificant (probably due to low number of patients), there was a trend in favor of larger diameter profile in the context of better outcome. The possible explanation might be that in smaller vessels the comparable level of neointima proliferation leads to more significant lumen area decrease and restenosis starts to meet angiographic criteria. In our study, there was a bit more net lumen gain in the main vessel and in the main branch in cases where BiOSS Expert1 stents with smaller diameters were implanted (Fig. 4).

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Figure 5. Restenosis pattern. MV, main vessel; MB, main branch; SB, side branch; No. 1–5, cases of restenosis corresponding with Table 6.

However, the comparison of BiOSS Expert1 stent to other paclitaxel‐eluting stents was favorable in the context of LLL. BiOSS Expert1 LLL was 0.26 mm (distal part) and 0.20 mm (proximal part), whereas the LLL for LucChopin2 stent and Taxus Liberté were 0.46–0.59 and 0.30 mm, respectively.25,26 Moreover, in our study, LLL values were smaller than in the original BiOSS Expert1 Registry (LLL proximal part, 0.56 mm, LLL distal part, 0.26 mm), which might suggest that this stent is better suited for bifurcations with more significant differences in diameters between the main vessel and the main branch, such as LMS/ LAD/LCX complex.7 Also, the profile of restenosis proved that the middle zone with only 2 struts is not a weak point of BiOSS Expert1 stent13 (Fig. 5). Worth mentioning is the fact that the new version of BiOSS stent is available on the market—sirolimus‐eluting BiOSS LIM1 stent. Further studies enable to answer the question if the used drug is more important or maybe the stent design is crucial. Study Limitations. This study has some limitations. These cases are selected by operators and therefore may not reflect use in all‐comer LMS lesions. In particular, in the first months of the study patients with so‐called “big” LMSs (reference diameter >4.0 mm) were excluded due to lack of proper stent diameter (initially the stents with diameters of 3.75  3.25 mm were the largest available). Also, there was no control group to compare the use of this dedicated bifurcation stent and stenting with other devices and techniques.

Conclusions Our study showed that dedicated bifurcation BiOSS Expert1 stent was a feasible device with promising short‐ and long‐term effectiveness and safety profile in distal LMS stenosis. In addition, we found the

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nonsignificant trend in favor of larger LMS diameter in the context of better outcome.

14.

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