Author + information
- Received December 5, 2006
- Revision received February 2, 2007
- Accepted February 19, 2007
- Published online June 19, 2007.
- John Cosgrave, MD⁎,
- Gloria Melzi, MD⁎,†,
- Simon Corbett, PhD⁎,
- Giuseppe G.L. Biondi-Zoccai, MD‡,
- Pierfrancesco Agostoni, MD§,
- Rade Babic, MD⁎,
- Flavio Airoldi, MD⁎,†,
- Alaide Chieffo, MD†,
- Giuseppe M. Sangiorgi, MD⁎,
- Matteo Montorfano, MD†,
- Iassen Michev, MD⁎,†,
- Mauro Carlino, MD† and
- Antonio Colombo, MD, FACC⁎,†,⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Antonio Colombo, EMO Centro Cuore Columbus, 48 Via M. Buonarroti, 20145 Milan, Italy.
Objectives This study was designed to compare the outcomes of paclitaxel-eluting stents (PES) and sirolimus-eluting stents (SES) in a contemporaneous cohort of real-world patients.
Background A number of randomized comparisons of PES and SES have shown unequivocal advantages for SES in angiographic end points such as late loss. However, the data on clinical outcomes are less consistent.
Methods All consecutive patients successfully treated with only SES or PES in de novo native vessel lesions between March 2003 and March 2005 were analyzed. Our end points were major adverse cardiac events (MACE), a composite of death, myocardial infarction (MI), target vessel revascularization (TVR), and target lesion revascularization (TLR). We also analyzed late loss and angiographic restenosis.
Results There were 609 patients (1,064 lesions) treated with PES and 674 patients (1,205 lesions) treated with SES. Diabetes mellitus was present in 26.8% of patients and multivessel disease in 75% of patients. Bifurcations made up 16.3% of lesions, chronic occlusions 9.5%, left main 4.8%, and American Heart Association/American College of Cardiology type B2/C 75.4%. Despite a higher late loss in the PES group (p = 0.0001), there were no differences in angiographic restenosis (PES 18% vs. SES 17.8%, p = 0.95), TLR (PES 11.9% vs. SES 11%, p = 0.47), or MACE (PES 21.3% vs. SES 21.1%, p = 0.95). The relative risk of MACE for the PES group was 1.02 (95% confidence interval [CI] 0.78 to 1.33). Multivariable analysis confirmed the lack of association of stent type with MACE (odds ratio 1.03 [95% CI 0.77 to 1.38], p = 0.83) and TLR (odds ratio 1.08 [95% CI 0.81 to 1.44], p = 0.61).
Conclusions In this complex cohort, both stent platforms demonstrated similar clinical outcomes despite different late loss.
Since the advent of drug-eluting stents (DES), much interest has focused on the comparison of the outcomes following implantation of the 2 initially available platforms: Cypher (Cordis/Johnson and Johnson, Warren, New Jersey) and Taxus (Boston Scientific, Natick, Massachusetts) (1,2). A number of randomized comparative studies have been performed; however, only SIRTAX (Sirolimus-Eluting and Paclitaxel-Eluting Stents for Coronary Revascularization) had a clinical primary end point which was 9-month major adverse cardiac events (MACE) (3–9). The data from these trials are conflicting, with SIRTAX demonstrating significantly lower target lesion revascularization (TLR) rates for the sirolimus-eluting stent (SES) compared to the paclitaxel-eluting stent (PES) and REALITY showing no difference. The other studies were underpowered for clinical end points, although ISAR-Diabetes (The Intracoronary Stenting and Angiographic Results: Do Diabetic Patients Derive Similar Benefit from Paclitaxel-Eluting and Sirolimus-Eluting Stents), ISAR-Desire (Intracoronary Stenting and Angiographic Results: Drug-Eluting Stents for In-Stent Restenosis), BASKET (Basel Stent Kosten Effektivitäts Trial), and CORPAL (Cordoba–Las Palmas Study) all demonstrated a nonsignificant trend toward a lower TLR rate for SES.
Despite the lack of clearly demonstrable differences in clinical events, all the studies have shown unequivocal advantages for SES in late loss. Surrogate end points such as late loss are attractive for comparing different DES, as a continuous variable is more powerful and hence reduces the sample size required to demonstrate a significant difference (10).
In light of the apparent paradox between clinical and surrogate end points in the randomized trials, a contemporaneous comparison between PES and SES was performed from our practice, which includes complex lesion subsets underrepresented in these trials.
All consecutive patients treated with either PES or SES between March 2003 and March 2005 were considered for retrospective analysis. The study period was selected as PES became available for clinical use in our institution in March 2003. The exclusion criteria were a mixture of different types of DES, a mixture of bare-metal stents and DES, in-stent restenosis, lesions located in bypass conduits, and primary balloon angioplasty.
All patients provided informed consent for both the procedure and subsequent data collection and analysis for research purposes. Procedural antiplatelet therapy and heparin dosing followed standard protocols (11). Platelet glycoprotein IIb/IIIa receptor inhibitors, an interventional approach, and intravascular ultrasound usage were used at the operator’s discretion. Stent selection, although not randomized, was performed without any specific preference, and it is our practice to alternate the implantation of 1 DES with the other.
Clinical definitions and follow-up
Clinical follow-up was performed by telephone contact or office visit at 1, 6, 9, and 12 months after the index procedure. Angiographic follow-up was suggested for all patients at 6 to 9 months after procedure. The clinical end points analyzed were periprocedural myocardial infarction (MI), death, after-discharge MI, target vessel revascularization (TVR), and TLR during the total follow-up period. Major adverse cardiac events, defined as a composite of death, MI, and TVR, were evaluated on a per patient basis. We analyzed TLR separately on a per lesion basis. All deaths were considered cardiac unless otherwise documented. We defined MI as a total creatine kinase elevation of >2 times the upper limit of normal in combination with an elevation in the creatine kinase-MB fraction. We defined TLR as repeat revascularization secondary to a stenosis ≥50% within the stent or within the 5-mm borders proximal or distal to the stent edge at the follow-up angiogram. We defined TVR as repeat revascularization of the target vessel.
Quantitative coronary angiography analysis
Coronary angiograms were analyzed using the validated edge detection system (CMS, version 5.2, MEDIS, Leiden, the Netherlands) (12). Angiographic restenosis was defined as diameter stenosis ≥50% by quantitative coronary angiography within a previously stented segment (stent and 5 mm proximal and distal) at the follow-up angiogram. Acute gain was defined as the difference between the minimal lumen diameter (MLD) at baseline and immediately after the procedure. Late lumen loss was calculated as the difference in MLD immediately after procedure and at angiographic follow-up.
Continuous variables are presented as means ± SD or medians (interquartile range [IQR]) and categorical variables as frequencies (%). The normality of the distribution of the continuous variables was tested by the Kolmogorov-Smirnov goodness-of-fit test. A skewness index was used to assess the nature of the asymmetry of the distribution. A normal distribution has a skewness value of zero, as it is symmetric. A distribution with a significant positive skewness is right-skewed and has a long right tail, whereas a negatively skewed distribution has a long left tail. Continuous variables were compared using independent sample Student tor Mann-Whitney Utest. Categorical variables were compared with chi-square statistic or Fisher exact test where appropriate. The Fisher exact test was used when the parametric assumptions underlying chi-square did not hold (conventionally, when the number of events in one or more classes is <5). The Mann-Whitney Utest was used when the parametric assumptions underlying the Student ttest did not hold. All the categorical variables were compared with the chi-square test, apart from acute thrombosis, subacute thrombosis, and coronary bypass surgery. All continuous variables were compared using the Student ttest, apart from the length of clinical follow-up and some of the quantitative angiographic parameters.
We calculated 95% confidence intervals (CI) for proportions by the Wilson method and the relative risk by the exact method (13,14).
Exploratory multivariable analysis was performed to assess the impact of stent type on the risk of MACE and TLR by logistic regression. The final model included variables associated at univariate analysis with MACE and TLR (all with a p value <0.1). The results are reported as adjusted odds ratios (OR) with associated 95% CI. To account for potential differences between the SES and PES cohorts, a propensity analysis was performed on a lesion-based setting for TLR using the propensity score as a covariate in the logistic regression model (15,16).
A p value of <0.05 was considered to be statistically significant, and all reported p-values are 2-sided. Statistical analysis was performed using SPSS version 11.5 (SPSS Inc., Chicago, Illinois) and Confidence Interval Analysis (13).
During the study period, a total of 1,907 patients were treated with a DES: 338 were treated for restenotic lesions, 232 had a mixture of different types of stent implanted, and 54 patients were treated for lesions located in bypass conduits.
The remaining 1,283 patients constituted the study cohort: 609 (1,064 lesions) received a PES and 674 (1,205 lesions) received a SES. Baseline demographic and procedural data are presented in Tables 1 and 2.⇓Overall, this was a complex cohort of patients, with a high percentage of multi-vessel disease (75%), prior bypass surgery (18%), and diabetes mellitus (27%). Lesion complexity was also noteworthy: there were chronic total occlusions (9.5%), bifurcations (16%), and a high percentage of American Heart Association/American College of Cardiology (AHA/ACC) type B2/C lesions (74%). This complexity was also represented by the number of stents implanted (range 1 to 10) and the total stent length per patient (range 8 to 255 mm). The patient characteristics were similar in the 2 groups, apart from a higher incidence of prior bypass surgery (p = 0.009) and insulin-requiring diabetes mellitus (p = 0.007) in the PES cohort. In the PES group, there were more AHA/ACC type B2/C lesions (p = 0.002), and there was a higher use of both cutting balloon (p = 0.002) and intravascular ultrasound (p = 0.0001).
Clinical follow-up was available in 99.1% of patients at a median of 13.9 months (IQR 11.5 to 17.5) after the procedure. Only 12 patients were lost to follow-up (4 in the PES group and 8 in the SES group). There was no difference in the length of follow-up between the 2 groups: 13.6 months (IQR 11.3 to 16.9) and 13.8 months (IQR 11.6 to 17.5) (p = 0.35) for PES and SES, respectively.
The MACE rate was 21.3% (95% CI 18.3% to 24.8%) in the PES group and 21.1% (95% CI 18.2% to 24.3%) in the SES group (p = 0.95), and there were no differences between the groups in the rate of follow-up death, MI, or late stent thrombosis (Table 3).The relative risk of MACE for the PES group compared to the SES was 1.02 (95 % CI 0.78 to 1.33). A multivariable model that included age, ejection fraction, multi-vessel disease, previous bypass surgery, intra-aortic balloon pump use, glycoprotein IIb/IIIa inhibitor administration, and diabetes mellitus showed that the type of stent implanted was not associated with MACE (OR 1.04 [95% CI 0.78 to 1.38], p = 0.8). Multi-vessel disease (OR 1.66 [95% CI 1.13 to 2.5], p = 0.01), intra-aortic balloon pump use (OR 3.19 [95% CI 1.6 to 6.33], p = 0.001), and diabetes mellitus (OR 2.42 [95% CI 1.79 to 3.27], p = 0.0001) were all associated with MACE.
A lesion-based analysis revealed that there was an 11.9% (95% CI 10.1% to 14%) TLR rate in PES compared with 11.0% (95% CI 9.3% to 12.8%) in the SES group (p = 0.47) and a TVR rate of 16.4% (95% CI 14.2% to 18.8%) compared with 15.1% (95% CI 13.2% to 17.2%) respectively (p = 0.39) (Table 3). The variables entered into the multivariable model for TLR were reference vessel diameter, postprocedural MLD, stent length, stent diameter, number of stents per lesion, and diabetes mellitus. This showed that stent type was not associated with TLR (OR 1.1 [95% CI 0.84 to 1.48], p = 0.47). The number of stents per lesion (OR 1.95 [95% CI 1.16 to 3.29], p = 0.012) and diabetes mellitus (OR 1.63 [95% CI 1.22 to 2.19], p = 0.001) were associated with TLR. A propensity analysis confirmed the lack of association between TLR and the type of stent implanted (OR 1.05 [95% CI 0.81 to 1.37], p = 0.7).
Quantitative angiographic analysis
Serial quantitative coronary angiography data are shown in Table 4.Angiographic follow-up was available in 766 lesions in the PES group (73.6%) and 829 lesions (70.3%) in the SES group. There was no statistical difference in restenosis rates between the PES and SES groups (18% [95% CI 15.5% to 20.9%] compared with 17.8% [95% CI 15.4% to 20.6%], p = 0.95). The late lumen loss was not normally distributed for both stents (p = 0.0001 by the Kolmogorov-Smirnov goodness-of-fit test) and was positively skewed with a long right tail (skewness index PES 0.89, SES 0.98). It was higher in the PES group: 0.45 mm (IQR 0.07 to 0.99) compared with 0.23 mm (IQR 0.02 to 0.69) in the SES group (p = 0.0001) (Fig. 1A).To further investigate this disparity between late loss and angiographic restenosis, we divided the late loss according to the presence of angiographic restenosis. Following this division, the distribution of late loss was normal for both stents (nonrestenotic lesions PES p = 0.54, SES p = 0.55, restenotic lesions PES p = 0.96, SES p = 0.48, by the Kolmogorov-Smirnov goodness-of-fit test) (Figs. 1B and 1C). The late loss of the nonrestenotic lesions was significantly higher in the PES group: 0.32 ± 0.55 mm compared with 0.06 ± 0.52 mm in the SES group (p = 0.0001). In the restenotic lesions, there was no difference in late loss between the 2 groups: PES 1.78 ± 0.72 mm compared with SES 1.7 ± 0.69 mm (p = 0.39). When the curves of the nonrestenotic and restenotic lesions were superimposed, there was an area of partial overlap for late loss values between 0.5 and 1.5 mm approximately (Figs. 2Aand 2B).
The main findings of this report are: 1) MACE and TLR rates in this complex cohort of patients were higher than those seen in the randomized trials; 2) there was no difference in the incidence of clinical end points between PES and SES; and 3) late loss was significantly greater following PES implantation, but this did not translate into a higher restenosis or TLR rate.
The MACE and TLR rates in this cohort were higher than those seen in the randomized trials. However, the randomized trials enrolled a select group of patients and lesions (1,2). The most complex cohort to date was enrolled in the TAXUS-V trial; this demonstrated a MACE rate of 15% and a TLR rate of 8.6% in the PES arm (17). This trial included only single-vessel intervention. Left main, aorto-ostial lesions, chronic total occlusions, bifurcations, calcified lesions, and the planned use of atherectomy were excluded. In contrast, our population comprised a spectrum of de novo native coronary lesions and was substantially more complex than those of the randomized trials. Multi-vessel disease, chronic total occlusions, left main, bifurcations, and diffuse disease that required long stent lengths were included. Therefore, the MACE and TLR rates are a more accurate representation of the efficacy of these stents in complex patients and lesions. Although the restenosis rates were high, the majority demonstrated a focal pattern and were amenable to repeat percutaneous therapy (18,19).
The performance of PES and SES was similar for MACE and TLR. This similarity was confirmed by multivariable analysis. The relatively high event rate in our population and the narrow CI make this observation more reliable. The relative risk of MACE for the PES cohort approaches unity (1.02 [95% CI 0.78 to 1.33]). The 2 groups were similar, but there were some differences that could have favored the SES group. The incidence of insulin-requiring diabetes, prior bypass surgery, AHA/ACC type B2/C lesions, and atheroablation were all higher in the PES cohort. Despite these differences, the outcomes were similar. To account for these baseline differences, a propensity analysis was performed on a lesion basis for TLR. This again confirmed the lack of association of stent type with revascularization. There was a numerically higher incidence of ST in patients treated with PES; however, this difference was not statistically significant and, because of the infrequent occurrence of ST, a specific large trial would be required to clarify this issue.
An apparent contradiction from our data is that late loss was significantly higher in the PES group, yet restenosis and TLR rates were similar between the 2 stents. This paradox can be explained in 2 ways. First, late loss is a calculated average of non-normally distributed data, and many patients have luminal loss that does not cause angiographic restenosis (20). A patient may have 1.5 mm of late loss in a 3.5-mm stent and hence not have restenosis, whereas another with the same degree of late loss but in a 2.5-mm stent would be characterized as restenosis. Indeed, in our data there is a partial overlap between the curves for restenotic and nonrestenotic lesions (Fig. 2). Thus, the correlation between the degree of late loss and restenosis is not a linear one; complex data transformations have been proposed to overcome this problem but with limited success (21,22). Another explanation may be that SES demonstrates an all-or-nothing response; in patients who do not develop restenosis, the late loss may be extremely low and approaches zero (23). In contrast, following PES implantation there is some degree of neointimal hyperplasia, as evidenced by the amount of late loss in the TAXUS-IV study (2). Although the TAXUS-IV and SIRIUS studies are not directly comparable, the degree of late loss is greater in TAXUS-IV (0.39 ± 0.5 mm compared with 0.17 ± 0.45 mm in SIRIUS). Despite this, the TLR rates were similar (3% and 4.1%, respectively). In the present study, the late loss in the nonrestenotic lesions was significantly higher following PES implantation (0.32 ± 0.55 mm compared with 0.06 ± 0.52, p = 0.0001). In contrast, for lesions with angiographic restenosis, the late loss was similar (PES 1.78 ± 0.72 mm, compared with SES 1.7 ± 0.69, p = 0.39).The difference in late loss between the 2 groups in our cohort was due primarily to the difference observed in nonrestenotic lesions. Thus, although SES seems to approach an all-or-none response, PES still exhibits some degree of neointimal hyperplasia (24). This difference in mild intimal hyperplasia is unlikely to affect clinical outcomes and explains the apparent paradox between higher late loss in PES and similar TLR rates.
Although our MACE and TLR rates are higher than those seen in the REALITY trial, the discordance between late loss and restenosis and TLR point in the same direction. This study enrolled 1,386 patients with 1 or 2 de novo lesions; however, left main, calcified lesions, total occlusions, acute MI, and pretreatment other than balloon angioplasty were all excluded (3). All patients were scheduled for angiography at 8 months, and the primary end point was binary angiographic restenosis. The study considered TLR, TVR, MACE, and late loss secondary end points. Angiographic follow-up was available in 88% of the PES patients and 93% of the SES patients. Mean late loss was significantly higher following PES (0.31 ± 0.44 mm vs. 0.09 ± 0.43 mm following SES, p < 0.001). However, both the restenosis (11.1% for PES and 9.6% for SES, p = 0.31) and TLR rates (6.1% and 6% respectively, p > 0.99) were similar.
The SIRTAX trial enrolled 1,012 patients with 1,401 lesions (4). Although this study enrolled consecutive real-world patients and included acute coronary syndromes (51.4%), chronic occlusions (1.8%), bifurcations (8.4%), left main (1.6%), and calcified lesions (34.5%), the overall percentage of AHA/ACC type B2/C lesions was still quite low at 36.4%. Therefore, the population is not directly comparable to ours in terms of patient and lesion complexity. The incidence of the primary end point of MACE at 9 months was significantly greater in the PES group (10.8% vs. 6.2%, p = 0.009), a fact that was driven primarily by differences in revascularization rates. Overall angiographic follow-up was available in 540 (53.4%) patients with 723 lesions. The in-stent late loss was again greater following PES implantation (0.25 ± 0.49 mm) compared with 0.12 ± 0.36 mm (p < 0.001), and there was a corresponding increase in in-stent and in-segment binary angiographic restenosis (in-stent 7.5% compared with 3.2%, p = 0.01 and in-segment 11.7% compared with 6.6%, p = 0.02, respectively). We must be cautious in drawing too many conclusions from this angiographic data in light of the low rate of angiographic follow-up.
A meta-analysis of the randomized comparative data has been published by Kastrati et al. (25). This analysis included data from REALITY, SIRTAX, CORPAL, TAXI, ISAR-DESIRE, and ISAR-DIABETES. The TLR rate for SES was 5.1% compared with PES at 7.8%, which gave a pooled OR of 0.64 (95% CI 0.49 to 0.84, p = 0.001).The restenosis rate was also lower for SES (9.3% compared with 13.1%, OR of 0.68, 95% CI 0.55 to 0.86, p = 0.001). Although these data are interesting, only 1 of the included trials had a clinical primary end point. It does not necessarily follow that grouping together such studies will generate sufficient power to result in a low likelihood of any differences identified in clinical end points remaining susceptible to a type 2 error (26).
The most important limitation is the lack of randomization. Despite this, the 2 groups were well matched, and our results were confirmed by both multivariable and propensity analysis. The relatively low rate of angiographic follow-up must also be considered a limitation, which may artificially elevate the rate of restenosis; however, the angiographic follow-up was similar in the 2 groups. Moreover, clinical follow-up was available in 99.1% of patients at a median of 13.9 months, and our primary goal was to comment on the clinical outcomes of the 2 study stents. We must also acknowledge that our sample size is relatively small to detect small differences in the event rates between the 2 stents.
Despite significant difference in the surrogate end point of late loss, PES and SES demonstrated similar clinical outcomes in this complex cohort. This suggests that late loss may not be a suitable end point for the evaluation of the performance of these 2 stents, especially in this real-world population.
- Abbreviations and Acronyms
- American Heart Association/American College of Cardiology
- confidence interval
- drug-eluting stent(s)
- interquartile range
- major adverse cardiac events
- myocardial infarction
- minimal lumen diameter
- odds ratio
- paclitaxel-eluting stent(s)
- sirolimus-eluting stent(s)
- target lesion revascularization
- target vessel revascularization
- Received December 5, 2006.
- Revision received February 2, 2007.
- Accepted February 19, 2007.
- American College of Cardiology Foundation
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