Author + information
- Received September 6, 2006
- Revision received March 5, 2007
- Accepted March 6, 2007
- Published online August 7, 2007.
- Andrejs Erglis, MD, PhD, FESC, FACC⁎,⁎ (, )
- Inga Narbute, MD⁎,
- Indulis Kumsars, MD⁎,
- Sanda Jegere, MD⁎,
- Iveta Mintale, MD⁎,
- Ilja Zakke, MD, FESC⁎,
- Uldis Strazdins, MD⁎ and
- Andris Saltups, MD, FACC, FRACP, MRACP†
- ↵⁎Reprint requests and correspondence:
Dr. Andrejs Erglis, Latvian Centre of Cardiology, Pauls Stradins Clinical University Hospital, Pilsonu 13, Riga, Latvia, LV 1002.
Objectives To optimize percutaneous coronary intervention (PCI) strategy for unprotected left main (LM) disease, we performed a randomized study: intravascular ultrasound (IVUS)-guided bare-metal stent (BMS) or paclitaxel-eluting stent (PES) implantation after lesion pre-treatment with cutting balloon (CB) for unprotected LM lesions.
Background Recent studies have shown promising results in terms of safety and feasibility for patients with LM disease who underwent PCI with stent implantation. However, comparison of BMS and PES for LM lesions has not yet been evaluated.
Methods One hundred three patients were randomly assigned to receive BMS (n = 50) or PES (n = 53) implantation. All interventions were IVUS guided, and CB pre-treatment before stenting was performed in all patients. All patients were scheduled for 6-month follow-up.
Results Baseline clinical characteristics were comparable in both cohorts. Stent implantation was successful in all lesions. Follow-up analysis showed binary restenosis in 11 (22%) BMS and in 3 (6%) PES patients (p = 0.021). By IVUS, percentage of neointimal volume obstruction at 6 months was reduced from 25.20 ± 22.02% with BMS to 16.60 ± 17.25% with PES (p = 0.02). At 6 months, the major adverse cardiac event-free survival rate was 70% in BMS and 87% in PES patients (p = 0.036).
Conclusions This study demonstrates that PCI of LM with IVUS guidance and CB pre-treatment is safe and effective. No serious procedure-related complications were observed, and clinical outcomes appeared to be good. Finally, the findings demonstrate that implantation of PES may be superior to BMS in the large-diameter LM vessel at 6 months, warranting the performance of a large-scale randomized trial.
Left main (LM) coronary artery disease is associated with a poor prognosis when treated medically, and its presence is an indication for coronary artery bypass surgery (CABG) in many centers (1–3). Several registries and studies show promising results in terms of safety and feasibility for patients with LM disease who underwent percutaneous coronary intervention (PCI) with stent implantation. However, common treatment trends and PCI strategy for these challenging and complicated lesions are not yet developed (4–7).
Intravascular ultrasound (IVUS) is a useful tool for treatment guidance in LM atherosclerotic lesions, owing to its accuracy in determining vessel dimensions and arterial wall structure (4,8,9). Additionally, various plaque modification and debulking techniques before stent implantation have shown improved luminal gain with a corresponding reduction in restenosis rates and target vessel revascularization compared with plain balloon angioplasty (10–12).
However, prospective studies have not yet been carried out to evaluate the use of cutting balloon (CB) in conjunction with stent deployment as a means to further optimize both short- and long-term outcomes for unprotected left main disease. There is also no clear answer as to which stent type (i.e., bare-metal or drug-eluting) should be used if adequate luminal dimensions can be achieved after IVUS-guided lesion pre-treatment.
To optimize PCI strategy for unprotected LM disease, we evaluated IVUS-guided bare-metal stent (BMS) or paclitaxel-eluting stent (PES) implantation after lesion pre-treatment with CB for unprotected LM lesions. This technique was devised based on our own previous studies as well as experiences at other centers. Our study objectives were 2-fold: 1) to evaluate in-hospital and midterm clinical, angiographic, and IVUS results in patients who underwent LM PCI with CB pre-treatment and IVUS guidance; and 2) to determine whether BMS or drug-eluting stents (DES) are more appropriate for LM stenting in terms of thrombosis risk, restenosis, and clinical adverse events.
Between January 2002 and January 2006, we enrolled 203 consecutive patients with unprotected LM disease undergoing PCI in our center into the LM PCI registry.
In February 2004, after preliminary successful LM interventions with BMS, we started randomization between BMS and PES. One hundred three (n = 103) patients were randomly assigned to receive Express or Liberte BMS (n = 50) or Taxus Express PES (n = 53) implantation (all stents manufactured by Boston Scientific Corp., Natick, Massachusetts).
In this randomized cohort (n = 103), all interventions were performed using IVUS guidance and CB pre-treatment for atherosclerotic plaque modification before stenting.
Eligible patients were those with clinically symptomatic LM disease with angiographic evidence of >50% diameter stenosis of LM suitable for stent implantation. The LM coronary artery was considered unprotected if there was no CABG to left anterior descending (LAD) artery branches or left circumflex (LCX) branches. All patients were good candidates for CABG. Informed written consents were obtained for all patients.
A maximum of 24 hours before the PCI procedure, all patients received 100 mg aspirin and a loading dose (300 mg) of clopidogrel. Patients were required to take clopidogrel 75 mg daily for at least 6 months after the PCI procedure. During the procedure, all patients were administered 10,000 IU of heparin or low-molecular-weight heparin depending on the patient’s weight. Glycoprotein IIb/IIIa receptor inhibitors were given at the operator’s discretion.
Coronary angiography was performed after intracoronary administration of nitroglycerine (0.2 mg). Quantitative coronary angiography (QCA) was performed off line, using a computer-based QCA-CMS system, version 4.0 (Medis Medical Imaging Systems, Leiden, the Netherlands), by the Riga core lab. The percentage diameter stenosis and minimal lumen diameter (MLD) were measured from diastolic frames before and after the PCI procedure and at 6-month follow-up. Angiographic restenosis was defined as 50% diameter stenosis at follow-up.
The IVUS images were obtained using the commercial IVUS system Galaxy II (Boston Scientific Corporation) and motorized pull-back at 0.5 mm/s. Pre- and post-procedure IVUS images were obtained for all patients, and follow-up IVUS images were obtained for 46 patients in the BMS group and 44 patients in the PES group. Analyses were performed by the Riga core lab. Longitudinal reconstruction of IVUS images was performed using a computer-based quantitative analysis system (QCU-CMS version 4.14, Medis Medical Imaging Systems). After digitalization of IVUS recordings at a frame rate of 30 images/s, longitudinal views of the studied segments were automatically processed. Using measurements from pre-interventional images, the lesion segment was classified as a culprit lesion with 5 mm of proximal and distal reference (most normal-appearing) segments. The corresponding frames at intervention stages, post-intervention, and follow-up were determined using peri- and intravascular landmarks (side branches, calcium, perivascular structures) from longitudinally reconstructed images. Vessel, stent, and lumen contours were automatically detected and manually corrected at 6-frame intervals; interpolated measurements of the remaining frames were automatically generated. In-stent late loss in lumen diameter (or lumen area) was calculated as post-procedural MLD (or minimum lumen area [MLA]) minus follow-up MLD (or MLA). In addition to standard IVUS measurements (MLD, MLA, and late loss), neointimal, lumen, stent, vessel, and plaque volumes were calculated at the lesion site. Neointimal volume index was calculated as neointimal volume divided by segment length. Percentage neointimal volume obstruction was defined as the ratio of the volume of neointimal hyperplasia to the volume of the stent multiplied by 100.
The IVUS and QCA measurements were performed by independent observers blinded to the treatment arm.
Cutting Balloon Intervention
The CB intervention was performed with a balloon-to-vessel ratio of 1:1, according to the IVUS media-to-media to the vessel at the lesion site, to achieve pre-specified IVUS criteria of MLA ≥9.0 mm2after stenting. The CB intervention was performed to cover the entire lesion length. Balloon inflations were performed 3 times with increasing pressure throughout the lesion.
After CB intervention, IVUS was performed to evaluate stent length and diameter.
All lesions at the ostium and body were treated with a single stent implantation. If the distal portion of the LM or a bifurcation was involved, the following stenting strategies were used. For most cases, stenting across the LCX ostium or provisional T stenting (if LCX ostium and/or proximal part was severely diseased) was performed. Final kissing balloon dilation was performed only in cases with suboptimal result at the LCX ostium. In other cases, a good result was achieved by opening the stent strut to the LCX with a small-diameter balloon or just after stent implantation.
After stent implantation, subsequent IVUS was performed to evaluate stent apposition and residual stenosis. If any segment on the treated vessel did not meet success criteria, additional balloon dilations with the noncompliant balloon were performed.
All patients were scheduled for clinical, angiographic, and IVUS follow-up at 6 months. All patients were also evaluated clinically during an office visit or by phone at 1 month. Repeat coronary angiography and IVUS evaluation was performed routinely at 6 months, or earlier if clinically indicated. The IVUS was performed to evaluate neointimal growth (volume, square, luminal diameter, and late lumen loss).
Major adverse cardiac events (MACE) were defined as death, myocardial infarction (MI), and target lesion revascularization (TLR). Patients with more than 1 event were assigned the highest rank event. All deaths were considered to be of cardiac origin unless a noncardiac origin was diagnosed. Myocardial infarction (MI) was diagnosed by elevation of myocardial damage biomarkers: 3-fold in troponin I and 5-fold in MB fraction of creatine kinase. Target lesion revascularization was defined as a repeat intervention (surgical or percutaneous) to treat a luminal stenosis in the stent or within the 5-mm segments adjacent to the stent, including the ostium of the LAD artery and/or LCX artery.
The PCI procedure was considered to be successful (procedure success) if the treated segment satisfied either of the following 2 success criteria: MLA ≥9.0 mm2by IVUS or residual angiographic stenosis <10% (if the minimal luminal reference vessel size by IVUS was smaller than 9.0 mm2).
Data were analyzed using SPSS (Statistical Package for the Social Sciences) software. Continuous variables are expressed as mean ± SD. Categoric variables were tested using contingency tables analyses (exact or chi-square approximations), and continuous variables were tested using unpaired Student ttest or Wilcoxon rank-sum test, depending on variable distribution. All statistical tests were 2-sided, and a p value of <0.05 was considered to be statistically significant. Survival curves were generated with the Kaplan-Meier method and were compared by use of the log rank test. All data for QCA and IVUS refer to the off-line analysis.
From February 2004 to November 2005, a total 103 randomized patients with unprotected LM stenosis underwent stent implantation with either BMS (n = 50) or PES (n = 53). Baseline clinical characteristics are presented in Table 1.Overall, there were no significant differences in baseline characteristics. The mean age of patients was 61.80 ± 10.84 years, the majority of patients were male (83%,) and the rate of hyperlipidemia was very high in both groups (BMS 68%, PES 81%; p = 0.173).
Baseline lesion and procedural characteristics
The baseline angiographic characteristics are summarized in Table 2.Procedural success was achieved in 100% of patients in both groups; however, there was 1 intraprocedural complication: perforation after CB intervention (successfully resolved with BMS stent implantation). Fifty patients (49%) underwent a percutaneous intervention in another major coronary segment as well.
There was a trend toward higher mean pre-procedural vessel diameter in the PES group compared with the BMS group (3.13 ± 0.74 mm vs. 3.38 ± 0.63 mm; p = 0.070). Mean treated segment length was comparable between the 2 treatment groups (11.49 ± 4.07 mm in PES vs. 11.64 ± 4.10 mm in BMS; p = 0.960).
To cross the lesion with the IVUS catheter, pre-dilation with a small balloon was used in 13 cases (26%) in the BMS group (diameter 2.50 ± 0.46 mm, length 21.23 ± 4.04 mm, mean pressure 11.69 ± 3.99 atm) and 6 (11%) in the PES group (diameter 2.33 ± 0.41 mm, length 21.33 ± 9.69 mm, mean pressure 12.83 ± 4.12 atm), although these differences did not reach statistical significance. Two-stent strategy (T stent method) was used in 1 case (2%) in the BMS group and 1 (2%) in the PES group (p > 0.99).
To optimize stent apposition, post-dilation with a larger balloon or noncompliant balloon was needed in 26 cases (52%) in the BMS group and 36 (68%) in the PES group (p = 0.111).
There were no significant differences observed in terms of clinical or IVUS results for “kissing post-dilation” compared with stent struts opened by small balloon. There were no incidents of death, stent thrombosis, Q-wave MI, or emergent bypass surgery during hospitalization in either group.
Angiographic results are presented in Table 3.Six-month angiographic follow-up and QCA analysis were performed for all 103 patients (100%). Follow-up analysis showed binary restenosis (≥50% diameter stenosis by QCA) in 11 (22%) in BMS and in 3 (6%) in PES patients (p = 0.021). There were no differences found regarding if lesion were located in ostium, body, or distal bifurcation.
The IVUS images were analyzable for 90 patients (87%; BMS n = 46 [92%]; PES n = 44 [83%]). In the PES group, statistically significant differences were observed in MLD late loss as well as in MLA late loss and neointimal volume compared with BMS. The MLD late loss in the DES group was 0.22 ± 0.22 versus 0.60 ± 0.33 in the BMS group (p < 0.001), and MLA late loss in the DES group was 1.07 ± 0.85 versus 2.70 ± 1.54 in the BMS group (p < 0.001). Also neointimal volume at 6 months was significantly reduced in the DES group 17.22 ± 17.10 versus 25.98 ± 21.84 in the BMS group (p = 0.014). Main procedural and 6-month follow-up IVUS measurements are summarized in Table 4.There were no differences found regarding lesion localization in the main stem.
In-hospital non–Q-wave MI was detected in 6 BMS patients (12%) and 4 DES patients (8%; p = 0.518).
Clinical follow-up data were available for all patients in both treatment groups. At 6 months there was 1 (2%) noncardiac death in the BMS group and 1 (2%) cardiac death in the PES group (p > 0.99). The incidence of Q-wave MI at 6 months was equal in both groups: 1 (2%) in the BMS group and 1 (2%) in the DES group (p > 0.99). No late stent thromboses were detected. Target lesion revascularization was performed in 8 BMS patients (16%) and 1 PES patient (2%; p = 0.014). All TLRs were clinically indicated, based on recurrent angina or positive stress test.
See Table 5for detailed clinical outcomes.
At 6 months, the major adverse cardiac event-free survival rate was 70% in the BMS group and 87% in the PES group (p = 0.036) (Fig. 1).
Since the first reports of percutaneous treatment of LM coronary artery stenosis, there has been debate over whether to treat these challenging lesions with surgery or percutaneous revascularization. Coronary artery bypass graft surgery has been demonstrated to prolong survival in patients with significant LM stenosis compared with medically treated patients (3).
Several studies and registries on percutaneous revascularization of LM stenosis have been conducted; however, many have included only small patient numbers in nonrandomized cohorts. The ULTIMA (Unprotected Left Main Trunk Intervention Multicenter Assessment) registry demonstrated high subacute cardiac mortality between high-risk patients and those with a low left ventricular ejection fraction (13,14). Therefore, the present study included only patients with well preserved left ventricular function in whom a good long-term prognosis could be expected if stent placement was successful.
Anatomically, left main distal lesions are bifurcation lesions. We support the use of 1 stent in bifurcation lesions to reduce acute complications (stent thrombosis, significant elevations of myocardial biomarkers) as well as the restenosis rate and need for repeat revascularization at the target segment (15,16). Performing main branch stenting, in LM cases means stenting across the ostium of the LCX artery, which presents the problem of plaque shifting to the LCX ostium. This may be avoided by pre-treating the lesion bed in the LAD artery as well as the LCX ostium with CB before stent deployment in the LM and deploying an additional stent in the LCX only in cases of severe disease in the LCX ostium and/or proximal portion. Good stent apposition may be achieved with lesion pre-treatment even without final kissing, which can be an additional unwanted factor for ischemia.
Role of IVUS guidance
There is no doubt that IVUS allows much more accurate assessment of lumen size, plaque area, and intimal composition compared with coronary angiography and QCA analysis (4,9). In the present study we used an IVUS-guided strategy for all LM percutaneous interventions. Some studies have demonstrated no difference in terms of restenosis rate between IVUS-guided and angiography-guided LM PCI procedures (4). This may be explained by the large reference vessel diameter; and, as we know from previous studies (MUSIC [Multicenter Ultrasound Guided Stent Implantation in the Coronaries]), post-interventional MLD and MLA are the most important predictors of restenosis (17).
Despite this evidence, IVUS guidance may be necessary in such a delicate and high-risk lesion cohort as LM stenoses for detection of exact plaque borders, verification of stent apposition, and geometry. However, an appropriately powered randomized trial of LM stenting with versus without IVUS is required before IVUS use can be considered mandatory in this lesion subset.
Role of CB pre-treatment
In large vessels, large MLD can be achieved after stent deployment by using only high-pressure balloon dilation. If necessary, atherosclerotic plaque modification will allow further stent expansion, although whether this improves the long-term outcomes of stent implantation is unknown.
Several debulking devices exist for reducing atherosclerotic plaque burden before stenting and for reducing subsequent restenosis as well (18,19). We found CB to be a reasonable tool for pre-treatment of atherosclerotic plaque before stent deployment. However, a randomized trial of left main stenting with versus without CB plaque modification is required to establish the safety of benefits of this technique. Moreover, whether CB sizing is best determined by IVUS guidance has not been established, but it seems a more reasonable tool for precise vessel dimension assessment.
Role of DES versus BMS
Starting with the RAVEL (Randomized Comparison of a Sirolimus-Eluting Stent with a Standard Stent for Coronary Revascularization) trial, numerous studies have demonstrated the benefits of DES over BMS in different lesion cohorts. Even in patients with multivessel disease in the ARTS II (Arterial Revascularization Therapies Study II) (20), DES was not associated with an increased need for repeat revascularization compared with CABG. Those excellent results allowed the extension of DES implantation to unprotected LM disease (21–23).
Our unprotected LM PCI registry was initiated long before the first DES became available in our institution. In addition, our strategy of IVUS-guided plaque pre-treatment with CB before stent deployment produced excellent results with BMS. Using DES, we are encouraged to treat longer segments to cover LM and proximal LAD. Thus, the stent size was matched to the LAD reference vessel diameter, and then the LM segment of the stent was further expanded with a larger-size noncompliant balloon if necessary. Angiographic appearance of the lesions often differs from IVUS data. Thus, there were discrepancies between lesion and deployed stent lengths.
The availability of DES has prompted the question: Should we use DES in all LM cases? Does DES provide benefit in such large-diameter vessels as LM? The present small prospective randomized study suggests that PES may be superior to BMS in unprotected LM stenoses.
The ongoing prospective multicenter randomized SYNTAX (Synergy Between PCI and Taxus and Cardiac Surgery) study promises to answer many more critical questions regarding the relative efficacy of DES compared with CABG.
The present study was carried out in a single center and had an open-label design. The study was underpowered by the small sample size. Furthermore, only intermediate-term (6 months) results were available. Longer-term follow-up in larger numbers of patients is required to establish the risk of early and stent thrombosis after thienopyridine discontinuation and to explore the optimal duration of dual antiplatelet therapy. Moreover, the modest sample size and open-label nature of the present trial led to differences between the 2 arms in vessel size, stent length and diameter, and inflation pressure. The extent to which these differences contributed to the observed results is unknown. Finally, larger registries and randomized trials are required to explore the optimal technique of LM stenting, especially when the distal bifurcation is involved, including 1- versus 2-stent technique, and the utility of IVUS guidance and plaque medication.
The present study suggests that percutaneous revascularization of LM with IVUS guidance and CB pre-treatment may be safe and effective. No serious procedure-related complications were observed, and intermediate-term outcomes were favorable. Finally, the findings of this study suggest that PES are superior to BMS in the large-diameter LM vessel at 6 months.
The authors gratefully acknowledge Dr. Andris Eglitis and Mr. Eriks Pudans for their permanent support and technical assistance. They also thank Mrs. Cecilia Schott for helpful discussion and advice.
Supported by Innovative Medical Foundation.
- Abbreviations and Acronyms
- bare-metal stent(s)
- coronary artery bypass grafting
- cutting balloon
- intravascular ultrasound
- left anterior descending
- left circumflex
- left main
- minimum lumen area
- minimal lumen diameter
- percutaneous coronary intervention
- paclitaxel-eluting stent(s)
- quantitative coronary analysis
- target lesion revascularization
- Received September 6, 2006.
- Revision received March 5, 2007.
- Accepted March 6, 2007.
- American College of Cardiology Foundation
- Conley M.J.,
- Ely R.L.,
- Kisslo J.,
- Lee K.L.,
- McNeer J.F.,
- Rosati R.A.
- Caracciolo E.A.,
- Davis K.B.,
- Sopko G.,
- et al.
- Park S.J.,
- Hong M.K.,
- Lee C.W.,
- et al.
- Silvestri M.,
- Barragan P.,
- Sainsous J.,
- et al.
- Black A.,
- Cortina R.,
- Bossi I.,
- Choussat R.,
- Fajadet J.,
- Marco J.
- Fassa A.A.,
- Wagatsuma K.,
- Higano S.T.,
- et al.
- Abizaid A.S.,
- Mintz G.S.,
- Abizaid A.,
- et al.
- Ellis S.G.,
- Tamai H.,
- Nobuyoshi M.,
- et al.
- Steigen T.K.,
- Maeng M.,
- Wiseth R.,
- et al.
- Colombo A.,
- Moses J.W.,
- Morice M.C.,
- et al.
- de Jaegere P.,
- Mudra H.,
- Figulla H.,
- et al.
- Moussa I.,
- Moses J.,
- Di Mario C.,
- et al.,
- Stenting After Optimal Lesion Debulking (SOLD) registry
- Prati F.,
- Di Mario C.,
- Moussa I.,
- et al.
- Serruys P.W.
- Valgimigli M.,
- Malagutti P.,
- Aoki J.,
- et al.
- Park S.J.,
- Kim Y.H.,
- Lee B.K.,
- et al.
- Price M.J.,
- Cristea E.,
- Sawhney N.,
- et al.