2.1

Study registration and inclusion/exclusion criteria

The study protocol design has been previously described and registered in clinicaltrial.gov (acronym Z-SEASIDE, number of registration: NCT01200693 ). The Ethical Committee of the Catholic University of the Sacred Heart approved the SEASIDE protocol and the follow-up of ZRS patients.

From September 2007 to November 2009, consecutive patients with documented coronary artery disease undergoing PCI on a bifurcated lesion at our Institution have been screened to enter the study. Patients with > 18 years of age, no ascertained or suspected contraindications to prolonged double antiplatelet therapy, no known hypersensitivity to sirolimus, everolimus, zotarolimus, cobalt, chromium, nickel, tungsten acrylic and fluoro-polymers, no acute (within 48 hours) ST-elevation acute myocardial infarction were considered eligible for the present study.

Angiographic criteria to define bifurcated lesions eligible for the study were:

• 1.
  

  lesions > 50% located in a major bifurcation point regardless of length, morphology and angulation.

  
  
• 2.
  

  TIMI ≥ 2 on both MV and SB

  
  
• 3.
  

  MV visual diameter ≥ 2.5 mm

  
  
• 4.
  

  SB visual diameter ≥ 2.0 mm

Bifurcated lesions were classified according to the Medina classification . Moreover, to provide an overall score of bifurcation anatomical complexity, the 7 Medina groups were grouped in 3 classes according to the number of diseased bifurcation segments: Class 1, one bifurcation site significantly involved (Medina groups: 1.0.0, 0.1.0, 0.0.1), Class 2, two bifurcation sites significantly involved (Medina groups 1.1.0, 0.1.1, 1.0.1), Class 3, three bifurcation sites significantly involved (Medina 1.1.1).

The first 150 patients fulfilling these clinical and angiographic characteristics entered the study and were randomized to the SES (Cypher Select, Cordis, Warren NJ) or the EES (Xience V, Abbott Vascular, Santa Clara, CA) stent . Thereafter, 75 consecutive patients fulfilling the study inclusion/exclusion criteria were scheduled to be treated by ZRS.

2.2

Percutaneous coronary interventions

PCIs were performed by radial or femoral approach according to the physician’s preference. After confirmation of the presence of the criteria for enrollment, patients were assigned to the type of stent to be implanted ( Fig. 1 ) according to the study design. In particular, the first 150 patients have been assigned to SES or EES according to a computer-generated random series of numbers, thereafter 75 consecutive patients were assigned to ZRS. PCI was performed according to the previously reported “provisional TAP-stenting strategy” . This means that all patients were treated by MV stenting first under SB protection with jailed guidewire technique, then SB rewiring was attempted with a BMW Universal (Abbott Vascular, Santa Clara, CA) (which represent the “workhorse wire” at our centre) and simultaneous kissing balloon was performed if considered necessary by the operator (kissing balloon being systematically attempted in case of large territories supplied by the SB or when SB exhibited tight stenosis or flow impairment after MV stenting). Then, if judged necessary by the operator, a second stent was implanted in the SB according to the TAP-stenting technique . Further details on the technical aspects of the provisional TAP-stenting approach have previously been reported .

Study flow-chart. SES: sirolimus eluting stent; EES: everolimus eluting stent; ZRS: zotarolimus (Resolute)-eluting stent; PCI: percutaneous coronary intervention; TAP: T And small Protrusion; 3DQCA: three-dimensional quantitative coronary angiography.

The type of materials used and the sequence of bifurcation intervention steps were prospectively collected. In particular, the occurrence of SB flow impairment after MV stenting, the attempt to rewire the SB after MV stenting, need of guidewire(s) different from the workhorse wire to re-wire SB after MV stenting and the failure to rewire or dilate the SB after MV stenting were prospectively assessed. Procedural success was defined as TIMI 3 in both MV and SB + visual residual stenosis < 20% in MV.

2.3

Peri-procedural medications

At the time of PCI, all patients were on double anti-platelet therapy with aspirin (100–160 mg daily) and clopidogrel (300 mg loading dose on the day before the PCI or 75 mg daily for more than 3 days before the procedure). Procedural anticoagulation was achieved with unfractioned heparin (70–100 U/kg intravenous bolus with further dose adjustment to maintain an activated clotting time of about 300 s). Use of glycoprotein IIb/IIIa inhibitors was per operator discretion. After the procedure, all patients received double anti-platelet therapy with aspirin 100 mg and clopidogrel 75 mg for 12 months with the indication to continue aspirin indefinitely. According to our internal guidelines on medical therapy of patients with documented coronary artery disease, patients were prescribed statins, beta-blockers and ACE-inhibitors. Usage of nitrates was not recommended after interventions.

2.4

Laboratory testing and follow-up

After PCI, all patients underwent post-PCI electrocardiogram, and 6-h and 24-h assessment of Troponin T and Creatine-kinase-MB (CK-MB) levels. Thereafter, further electrocardiogram and myocardial necrosis biomarkers evaluations were performed if clinically indicated.

After PCI, the in-hospital clinical course was carefully monitored; after discharge, patients were followed-up by hospital visit or by phone interview at 6, 9, 12, 18 and 24 months. According to the clinical practice of our centre, all patients with symptoms’ recurrence and those with inducible ischemia were recommended to repeat coronary angiography. Patients records and angiographic studies were carefully reviewed for all suspected adverse events prior to adjudication.

The clinical events were defined as follows:

• –
  

  Death (the cause of death has been ascertained by reviewing of the available clinical records and all deaths without clear non-cardiac cause were considered as cardiac death)

  
  
• –
  

  Myocardial infarction (MI): ST-Elevation MI (> 20 min lasting chest pain with > 0.1 mV ST elevation in at least two contiguous leads) or non ST-Elevation MI (typical chest pain with documentation of transient > 0.1 mV ST segment depression or T wave modifications in at least two contiguous leads) with any increase in myocardial necrosis biomarkers above the 99th percentile of the upper reference limit. Post-procedural MI was defined as CK-MB increase > 3 times the upper reference limit in patients with normal Troponin T levels before PCI and CK-MB increase > 3 times the pre-PCI CK-MB levels in patients with abnormal Troponin T levels before PCI.

  
  
• –
  

  Target vessel revascularization (TVR): repeat PCI or coronary surgery on the target vessel due to recurrent ischemia.

  
  
• –
  

  Major adverse coronary events (MACE): death or MI or TVR

  
  
• –
  

  Target bifurcation related MACE: any MACE not clearly caused by another vessel

  
  
• –
  

  Target bifurcation angiographic failure: ≥ 50% restenosis on the main vessel or TIMI flow < 3 on the side-branch at angiography eventually performed during the follow-up.

  
  
• –
  

  stent thrombosis was defined according to the ARC criteria as follows: “definite” = angiography- or autopsy-confirmed ST; “probable” = any unexplained death within first 30 days or any myocardial infarction in the territory of the stent and in the absence of any other obvious cause.

2.5

Angiographic analyses

Pre-PCI, post-PCI and follow-up angiography was performed with the aim of allowing three-dimensional reconstruction and quantitative coronary analysis (3DQCA). Accordingly, at least two views were obtained at least 30° apart each other. In cases of suboptimal imaging a third obtained view was used to improve the 3D reconstruction accuracy.

Off-line 3DQCA analysis using the previously validated CardiOp-B System was performed by a trained interventional cardiologist (DT) who was blinded to clinical and procedural characteristics, to patients’ status and to outcome.

Using the 3DQCA reconstruction, the following pre- and post-PCI parameters were obtained:

• –
  

  Reference diameter (RD) of the MV

  
  
• –
  

  Minimal lumen diameter (MLD) and area (MLA) of the MV

  
  
• –
  

  Percentage area stenosis of the MV

  
  
• –
  

  RD of the SB

  
  
• –
  

  MLD and MLA of the SB

  
  
• –
  

  Percentage area stenosis of the SB

  
  
• –
  

  MLD and MLA of the SB ostium (using the software’s scroll bar tool)

  
  
• –
  

  Bifurcation proximal angle (angle between proximal MV and SB)

  
  
• –
  

  Bifurcation distal angle (angle between SB and distal MV)

2.6

Study end-points

The study was primarily aimed at assessing the procedural outcome and the acute angiographic results of bifurcated lesions treated by the three type of DES.

The primary procedural and angiographic end-points were respectively:

• –
  

  “SB trouble” (composite of the occurrence of at least one of the following procedural parameters: 1. SB TIMI flow < 3 after MV stenting; 2. need of guidewire(s) different from the workhorse wire to re-wire SB after MV stenting; 3. failure to re-wire the SB after MV stenting; 4. failure to dilate the SB after MV stenting and SB re-wiring)

  
  
• –
  

  “SB acute angiographic result” (comparison of the 3DQCA-estimated MLD of the SB ostium).

Such primary end-points have been ideated and defined for the first time in the present study. Accordingly, no published data in the literature were available for any of the study end-points thus limiting the strength of sample size calculations. The assumptions used to define the sample size for the comparison between SES and EES have been reported elsewhere and for the planning of ZRS arm, we hypothesized (on the basis of the stent design issues described in the introduction section) that the performance of ZRS should be comparable to that of EES and superior to SES. Accordingly, the same numerosity planned for EES arm was used for ZRS one.

The following angiographic and clinical end-points were pre-defined secondary study end-points:

• –
  

  3DQCA-estimated MLA in the SB ostium

  
  
• –
  

  “target bifurcation failure” (TBF): defined as target bifurcation-related MACE or target bifurcation angiographic failure in the absence of MACE.

2.7

Statistical analysis

All analyses were performed according to the intention to treat. Continuous variables were tested for normality and for homogeneity of variance by Kolmogorov–Smirnov and Levene respectively and compared by unpaired T or Mann–Whitney U tests as appropriate. Chi-square tests (Fisher corrected when appropriate) were used to compare discrete variables (reported as raw numbers [%]). Multivariate analysis, using a binary logistic regression model including factors with significant association at univariate analysis (P ≤ 0.05), was performed to identify variables predictive of “SB trouble” and TBF. A two tailed, p value ≤ 0.05 was established as the level of statistical significance for all tests. Statistical analyses were carried out using version 19.0 of IBM-SPSS Statistics software package (Chicago, IL, USA) for Windows.

2.1

Study registration and inclusion/exclusion criteria

The study protocol design has been previously described and registered in clinicaltrial.gov (acronym Z-SEASIDE, number of registration: NCT01200693 ). The Ethical Committee of the Catholic University of the Sacred Heart approved the SEASIDE protocol and the follow-up of ZRS patients.

From September 2007 to November 2009, consecutive patients with documented coronary artery disease undergoing PCI on a bifurcated lesion at our Institution have been screened to enter the study. Patients with > 18 years of age, no ascertained or suspected contraindications to prolonged double antiplatelet therapy, no known hypersensitivity to sirolimus, everolimus, zotarolimus, cobalt, chromium, nickel, tungsten acrylic and fluoro-polymers, no acute (within 48 hours) ST-elevation acute myocardial infarction were considered eligible for the present study.

Angiographic criteria to define bifurcated lesions eligible for the study were:

• 1.
  

  lesions > 50% located in a major bifurcation point regardless of length, morphology and angulation.

  
  
• 2.
  

  TIMI ≥ 2 on both MV and SB

  
  
• 3.
  

  MV visual diameter ≥ 2.5 mm

  
  
• 4.
  

  SB visual diameter ≥ 2.0 mm

Bifurcated lesions were classified according to the Medina classification . Moreover, to provide an overall score of bifurcation anatomical complexity, the 7 Medina groups were grouped in 3 classes according to the number of diseased bifurcation segments: Class 1, one bifurcation site significantly involved (Medina groups: 1.0.0, 0.1.0, 0.0.1), Class 2, two bifurcation sites significantly involved (Medina groups 1.1.0, 0.1.1, 1.0.1), Class 3, three bifurcation sites significantly involved (Medina 1.1.1).

The first 150 patients fulfilling these clinical and angiographic characteristics entered the study and were randomized to the SES (Cypher Select, Cordis, Warren NJ) or the EES (Xience V, Abbott Vascular, Santa Clara, CA) stent . Thereafter, 75 consecutive patients fulfilling the study inclusion/exclusion criteria were scheduled to be treated by ZRS.

2.2

Percutaneous coronary interventions

PCIs were performed by radial or femoral approach according to the physician’s preference. After confirmation of the presence of the criteria for enrollment, patients were assigned to the type of stent to be implanted ( Fig. 1 ) according to the study design. In particular, the first 150 patients have been assigned to SES or EES according to a computer-generated random series of numbers, thereafter 75 consecutive patients were assigned to ZRS. PCI was performed according to the previously reported “provisional TAP-stenting strategy” . This means that all patients were treated by MV stenting first under SB protection with jailed guidewire technique, then SB rewiring was attempted with a BMW Universal (Abbott Vascular, Santa Clara, CA) (which represent the “workhorse wire” at our centre) and simultaneous kissing balloon was performed if considered necessary by the operator (kissing balloon being systematically attempted in case of large territories supplied by the SB or when SB exhibited tight stenosis or flow impairment after MV stenting). Then, if judged necessary by the operator, a second stent was implanted in the SB according to the TAP-stenting technique . Further details on the technical aspects of the provisional TAP-stenting approach have previously been reported .

Study flow-chart. SES: sirolimus eluting stent; EES: everolimus eluting stent; ZRS: zotarolimus (Resolute)-eluting stent; PCI: percutaneous coronary intervention; TAP: T And small Protrusion; 3DQCA: three-dimensional quantitative coronary angiography.

The type of materials used and the sequence of bifurcation intervention steps were prospectively collected. In particular, the occurrence of SB flow impairment after MV stenting, the attempt to rewire the SB after MV stenting, need of guidewire(s) different from the workhorse wire to re-wire SB after MV stenting and the failure to rewire or dilate the SB after MV stenting were prospectively assessed. Procedural success was defined as TIMI 3 in both MV and SB + visual residual stenosis < 20% in MV.

2.3

Peri-procedural medications

At the time of PCI, all patients were on double anti-platelet therapy with aspirin (100–160 mg daily) and clopidogrel (300 mg loading dose on the day before the PCI or 75 mg daily for more than 3 days before the procedure). Procedural anticoagulation was achieved with unfractioned heparin (70–100 U/kg intravenous bolus with further dose adjustment to maintain an activated clotting time of about 300 s). Use of glycoprotein IIb/IIIa inhibitors was per operator discretion. After the procedure, all patients received double anti-platelet therapy with aspirin 100 mg and clopidogrel 75 mg for 12 months with the indication to continue aspirin indefinitely. According to our internal guidelines on medical therapy of patients with documented coronary artery disease, patients were prescribed statins, beta-blockers and ACE-inhibitors. Usage of nitrates was not recommended after interventions.

2.4

Laboratory testing and follow-up

After PCI, all patients underwent post-PCI electrocardiogram, and 6-h and 24-h assessment of Troponin T and Creatine-kinase-MB (CK-MB) levels. Thereafter, further electrocardiogram and myocardial necrosis biomarkers evaluations were performed if clinically indicated.

After PCI, the in-hospital clinical course was carefully monitored; after discharge, patients were followed-up by hospital visit or by phone interview at 6, 9, 12, 18 and 24 months. According to the clinical practice of our centre, all patients with symptoms’ recurrence and those with inducible ischemia were recommended to repeat coronary angiography. Patients records and angiographic studies were carefully reviewed for all suspected adverse events prior to adjudication.

The clinical events were defined as follows:

• –
  

  Death (the cause of death has been ascertained by reviewing of the available clinical records and all deaths without clear non-cardiac cause were considered as cardiac death)

  
  
• –
  

  Myocardial infarction (MI): ST-Elevation MI (> 20 min lasting chest pain with > 0.1 mV ST elevation in at least two contiguous leads) or non ST-Elevation MI (typical chest pain with documentation of transient > 0.1 mV ST segment depression or T wave modifications in at least two contiguous leads) with any increase in myocardial necrosis biomarkers above the 99th percentile of the upper reference limit. Post-procedural MI was defined as CK-MB increase > 3 times the upper reference limit in patients with normal Troponin T levels before PCI and CK-MB increase > 3 times the pre-PCI CK-MB levels in patients with abnormal Troponin T levels before PCI.

  
  
• –
  

  Target vessel revascularization (TVR): repeat PCI or coronary surgery on the target vessel due to recurrent ischemia.

  
  
• –
  

  Major adverse coronary events (MACE): death or MI or TVR

  
  
• –
  

  Target bifurcation related MACE: any MACE not clearly caused by another vessel

  
  
• –
  

  Target bifurcation angiographic failure: ≥ 50% restenosis on the main vessel or TIMI flow < 3 on the side-branch at angiography eventually performed during the follow-up.

  
  
• –
  

  stent thrombosis was defined according to the ARC criteria as follows: “definite” = angiography- or autopsy-confirmed ST; “probable” = any unexplained death within first 30 days or any myocardial infarction in the territory of the stent and in the absence of any other obvious cause.

2.5

Angiographic analyses

Pre-PCI, post-PCI and follow-up angiography was performed with the aim of allowing three-dimensional reconstruction and quantitative coronary analysis (3DQCA). Accordingly, at least two views were obtained at least 30° apart each other. In cases of suboptimal imaging a third obtained view was used to improve the 3D reconstruction accuracy.

Off-line 3DQCA analysis using the previously validated CardiOp-B System was performed by a trained interventional cardiologist (DT) who was blinded to clinical and procedural characteristics, to patients’ status and to outcome.

Using the 3DQCA reconstruction, the following pre- and post-PCI parameters were obtained:

• –
  

  Reference diameter (RD) of the MV

  
  
• –
  

  Minimal lumen diameter (MLD) and area (MLA) of the MV

  
  
• –
  

  Percentage area stenosis of the MV

  
  
• –
  

  RD of the SB

  
  
• –
  

  MLD and MLA of the SB

  
  
• –
  

  Percentage area stenosis of the SB

  
  
• –
  

  MLD and MLA of the SB ostium (using the software’s scroll bar tool)

  
  
• –
  

  Bifurcation proximal angle (angle between proximal MV and SB)

  
  
• –
  

  Bifurcation distal angle (angle between SB and distal MV)

2.6

Study end-points

The study was primarily aimed at assessing the procedural outcome and the acute angiographic results of bifurcated lesions treated by the three type of DES.

The primary procedural and angiographic end-points were respectively:

• –
  

  “SB trouble” (composite of the occurrence of at least one of the following procedural parameters: 1. SB TIMI flow < 3 after MV stenting; 2. need of guidewire(s) different from the workhorse wire to re-wire SB after MV stenting; 3. failure to re-wire the SB after MV stenting; 4. failure to dilate the SB after MV stenting and SB re-wiring)

  
  
• –
  

  “SB acute angiographic result” (comparison of the 3DQCA-estimated MLD of the SB ostium).

Such primary end-points have been ideated and defined for the first time in the present study. Accordingly, no published data in the literature were available for any of the study end-points thus limiting the strength of sample size calculations. The assumptions used to define the sample size for the comparison between SES and EES have been reported elsewhere and for the planning of ZRS arm, we hypothesized (on the basis of the stent design issues described in the introduction section) that the performance of ZRS should be comparable to that of EES and superior to SES. Accordingly, the same numerosity planned for EES arm was used for ZRS one.

The following angiographic and clinical end-points were pre-defined secondary study end-points:

• –
  

  3DQCA-estimated MLA in the SB ostium

  
  
• –
  

  “target bifurcation failure” (TBF): defined as target bifurcation-related MACE or target bifurcation angiographic failure in the absence of MACE.

2.7

Statistical analysis

All analyses were performed according to the intention to treat. Continuous variables were tested for normality and for homogeneity of variance by Kolmogorov–Smirnov and Levene respectively and compared by unpaired T or Mann–Whitney U tests as appropriate. Chi-square tests (Fisher corrected when appropriate) were used to compare discrete variables (reported as raw numbers [%]). Multivariate analysis, using a binary logistic regression model including factors with significant association at univariate analysis (P ≤ 0.05), was performed to identify variables predictive of “SB trouble” and TBF. A two tailed, p value ≤ 0.05 was established as the level of statistical significance for all tests. Statistical analyses were carried out using version 19.0 of IBM-SPSS Statistics software package (Chicago, IL, USA) for Windows.