Author + information
- Received June 28, 2004
- Revision received October 18, 2004
- Accepted October 25, 2004
- Published online April 19, 2005.
- Jeffrey W. Moses, MD, FACC⁎,†,
- Roxana Mehran, MD, FACC⁎,†,
- Eugenia Nikolsky, MD⁎,†,
- John M. Lasala, MD, FACC‡,1,
- Woodrow Corey, MD, FACC§,
- Glenn Albin, MD, FACC∥,
- Cary Hirsch, MD, FACC¶,
- Martin B. Leon, MD, FACC⁎,†,
- Mary E. Russell, MD, FACC#,2,
- Stephen G. Ellis, MD, FACC⁎⁎,1 and
- Gregg W. Stone, MD, FACC⁎,†,1,⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Gregg W. Stone, The Cardiovascular Research Foundation, 55 East 59th Street, 6th floor, New York, New York 10022.
Objectives We sought to investigate the outcomes of paclitaxel-eluting stent implantation in patients with unstable angina or non-ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention (PCI).
Background Whether the paclitaxel-eluting stent is safe and effective in patients with acute coronary syndromes (ACS) is unknown.
Methods In the TAXUS-IV trial, 1,314 patients with stable or unstable ischemic syndromes undergoing PCI were randomized to treatment with either the slow-release, polymer-based, paclitaxel-eluting TAXUS stent or a bare-metal EXPRESS stent (Boston Scientific Corp., Natick, Massachusetts). The results were stratified by the acuity of the presenting clinical syndrome.
Results Acute coronary syndromes were present in 450 patients (34.2%), 237 of whom were assigned to paclitaxel-eluting stents and 213 to bare-metal stents. The baseline and procedural characteristics were well matched between the groups. Clinical outcomes at 30 days were similar with both stents. At one-year follow-up, patients with ACS assigned to the paclitaxel-eluting stent compared to the control stent had strikingly lower rates of target lesion revascularization (TLR) (3.9% vs. 16.0%, p < 0.0001) and major adverse cardiac events (11.1 vs. 21.7%, p = 0.002). By multivariate analysis, ACS was an independent predictor of in-stent restenosis in the cohort treated with bare-metal stents (hazard ratio [HR] = 2.03 [95% confidence interval (CI) 1.05 to 3.92], p = 0.035), while among patients randomized to the paclitaxel-eluting stents, ACS was an independent predictor of freedom from restenosis (HR = 0.27 [95% CI 0.08 to 0.97], p = 0.04).
Conclusions The use of the paclitaxel-eluting TAXUS stent was safe in patients with unstable ischemic syndromes, and was associated with marked reduction of ischemia-driven TLR and adverse cardiac events at one year.
Acute coronary syndromes (ACS) account for over one million hospital admissions in the U.S. annually and, therefore, represent a major public health concern (1). Compelling evidence from recent randomized clinical trials has demonstrated that intermediate- and high-risk patients with ACS derive significant reduction in both morbidity and mortality with an early invasive strategy (2–4). As a result, percutaneous coronary intervention (PCI) has become a standard treatment modality for many patients with ACS. Continued technical evolution of catheter-based procedures including coronary stents combined with aggressive antiplatelet and antithrombin therapy has resulted in significantly improved short- and intermediate-term clinical outcomes (4,5). However, due to in-stent restenosis, the rate of one-year clinical events in patients with ACS still remains as high as 20%, contributing to patient morbidity and increased health care resource consumption (6,7).
Recently, several randomized clinical trials have demonstrated the ability of drug-eluting stents to profoundly suppress in-stent neointimal hyperplasia, the main pathological substrate for in-stent restenosis, and to dramatically reduce clinical and angiographic restenosis (8–11). Whether these devices are safe and effective in patients with ACS, in whom plaque rupture and thrombus formation is often present, is unknown (12). Therefore, we examined the outcomes of patients presenting with unstable angina and non-ST-segment elevation myocardial infarction (MI) in the prospective, double-blind, randomized, multicenter TAXUS-IV trial comparing the paclitaxel-eluting stent with a bare-metal stent.
The TAXUS-IV protocol, inclusion and exclusion criteria, and principal results have been recently reported (11). Briefly, 1,314 patients of at least 18 years of age with stable or unstable ischemic syndromes undergoing PCI for a single de novo lesion in a native coronary artery were randomized to treatment with either the slow-release, polymer-based, paclitaxel-eluting stent (TAXUS, Boston Scientific Corp., Natick, Massachusetts) or a visually indistinguishable bare-metal stent (EXPRESS, Boston Scientific, Corp.). Inclusion criteria required a lesion with visually estimated length of 10 to 28 mm, and reference vessel diameter of 2.5 to 3.75 mm. General eligibility criteria for enrollment have been described previously (11). Specifically, in regards to the present analysis, clinical syndrome acuity was not an exclusion criteria, and patients with ACS (unstable angina or recent non-ST-segment elevation MI) were encouraged for recruitment. However, patients with occluded coronary vessels (Thrombolysis In Myocardial Infarction flow grade 0/1) and obvious angiographic thrombus were excluded, as were those with acute ST-segment elevation MI. At the time of the procedure, the creatine kinase (CK)-MB level had to be ≤2 × the local laboratory’s upper limits of normal. An elevated troponin level was not an exclusion criterion.
Before catheterization, patients received 325 mg aspirin and 300 mg of clopidogrel. Unfractionated heparin was administered during the PCI per standard practice. After the procedure, patients were maintained on aspirin 325 mg daily indefinitely and clopidogrel 75 mg daily for at least six months. All other treatments, including platelet glycoprotein IIb/IIIa receptor inhibitors, were at the discretion of the physicians, whether before, during, or after the procedure.
Follow-up angiography at nine months was completed in 559 patients of a pre-specified cohort of 732 patients. Clinical follow-up was scheduled at one, four, and nine months, at one year, and yearly thereafter for five years. The end points have been previously defined, and were all adjudicated by an independent clinical events committee. All baseline and follow-up films were analyzed at an independent angiographic core laboratory blinded to clinical events. Major adverse cardiac events (MACE) were defined as death from cardiac causes, MI, or ischemia-driven target vessel revascularization (TVR). Unstable angina was categorized according to the Braunwald classification that takes into account the severity of angina (class I to III) and clinical circumstances related to the occurrence of the angina (class A, B, and C, corresponding to angina developing in the presence or absence of an extracardiac condition or within two weeks of acute MI, respectively) (13). Non-ST-segment elevation MI before PCI was defined as a CK-MB or troponin level greater than the upper limit of normal without evidence of acute ST-segment elevation MI.
Categorical variables were compared with the Fisher exact test for pairwise comparisons or chi-square test for trend for multiple group comparisons. Continuous variables are presented as mean ± SD, and were compared using the Student ttest. Survival estimated were created using Kaplan-Meier methodology and compared with the log-rank test. Multivariate analysis of predictors of TVR were identified using Cox proportional hazards regression with stepwise selection using entry and exit criteria of p < 0.1. The candidate variables entered in the model included age, gender, angina status (unstable vs. not unstable), diabetes mellitus, hypertension, hyperlipidemia, current smoking, history of MI, creatinine clearance, left anterior descending artery target vessel, ejection fraction, randomization to paclitaxel-eluting stent, stent length and diameter, total length of the stented segment, amount of stents, the use of non-study stents, balloon-to-artery ratio, target vessel reference diameter, and target vessel angulation.
Acute coronary syndrome was present in 450 of the 1,314 enrolled patients (34.2%); 237 patients (201 patients with unstable angina and 36 patients with non-ST-segment elevation MI) were assigned to paclitaxel-eluting stents and 213 patients (186 and 27 patients, respectively) to bare-metal stents. As seen in Table 1,the baseline clinical and angiographic features of patients with ACS were well matched between the two randomized groups, including the severity of angina, with approximately two-thirds of patients in each group having angina at rest (class IIB/C or IIIB/C), and about one-third of patients having angina at rest within the preceding 48 h (class IIIB/C). Approximately 20% of patients in both groups presented with non-ST-segment elevation MI. Pre-procedure medication use was similar in the two groups with virtually all patients treated with aspirin and clopidogrel, two-thirds treated with beta-blockers, and approximately one-third of the patients treated with either unfractionated or low-molecular-weight heparin. Pre-procedural platelet glycoprotein IIb/IIIa receptor inhibitors were administered in <10% of patients.
Procedural characteristics did not differ significantly between the ACS patients treated with paclitaxel-eluting and bare-metal stents (Table 2).Platelet glycoprotein IIb/IIIa receptor inhibitors were administered to more than one-half of the patients in both groups, with a similar proportion receiving abciximab (19.0% vs. 19.7%, respectively), eptifibatide (33.8% vs. 31.5%, respectively), and tirofiban (5.9% vs. 5.6%, respectively).
As seen in Table 3,there were no significant differences in 30-day clinical end points between patients with ACS treated with paclitaxel-eluting stents compared to bare-metal stents. At one-year follow-up, however, use of the paclitaxel-eluting stent in patients with ACS was associated with a reduction in target lesion revascularization (TLR) by 78% (95% confidence interval [CI] 53% to 89%), TVR by 65% (95% CI 35% to 81%) and composite MACE by 51% (95% CI 21% to 70%) (Fig. 1).In addition, a trend was present toward a 37% reduction in the rate of MI at one year in patients with unstable angina or non-ST-segment elevation MI treated with paclitaxel-eluting stent. A total of four patients developed stent thrombosis: two patients were treated with paclitaxel-eluting stents (both received glycoprotein IIb/IIIa receptor inhibitors during the index procedure), and two patients were treated with bare-metal stents (neither of whom received platelet glycoprotein IIb/IIIa receptor inhibitors).
By multivariate analysis, assignment to the paclitaxel-eluting stent in patients with ACS was a significant independent predictor of freedom from one-year TVR (hazard ratio [HR] = 0.40 [95% CI 0.28 to 0.57], p < 0.0001).
Among patients with ACS, 101 patients treated with paclitaxel-eluting stents and 87 patients treated with bare-metal stents completed nine-month angiographic follow-up. Patients assigned to receive the paclitaxel-eluting stent had significantly less late loss both in-stent and within the analysis segment resulting in a marked 87% reduction of in-stent and 86% reduction of analysis segment restenosis (Table 4).When restenosis did occur after TAXUS stent implantation, it was nearly always focal in nature and significantly shorter in length than after bare-metal stents.
Paclitaxel-eluting stent arm: patients with stable versus unstable ischemic syndromes
The outcomes of the 237 patients with ACS treated with paclitaxel-eluting stent were further compared to the 425 patients with stable ischemic syndromes also treated with the TAXUS stent. Patients with ACS compared to those with stable ischemic syndromes were more commonly female (33.3% vs. 25.4%, p = 0.03) and current smokers (29.6% vs. 21.2%, p = 0.02), had a higher incidence of previous MI (37.1% vs. 26.8%, p = 0.006), and were more commonly treated before the procedure with unfractionated heparin (19.4% vs. 6.4%, p < 0.0001), low-molecular-weight heparin (17.7% vs. 4.5%, p < 0.0001), platelet glycoprotein IIb/IIIa receptor inhibitors (9.7% vs. 4.0%, p = 0.006), beta-blockers (70.0% vs. 58.6%, p = 0.004), and nitrates (55.3% vs. 28.7%, p < 0.0001).
Patients with ACS compared to those with stable ischemic syndromes treated with the TAXUS stent had a trend toward a higher rate of stent thrombosis at 30 days (0.8% vs. 0.0%, p = 0.06), but not at 1 year (0.8% vs. 0.5%, respectively, p = 0.55). There was no formal interaction, however, between clinical syndrome acuity (ACS vs. non-ACS) and randomization to the TAXUS stent rather than the bare-metal control stent on the occurrence of stent thrombosis at either 30 days or 1 year (Breslow-Day test for homogeneity p = 0.23 and 0.89, respectively).
As seen in Figure 2,the one-year rates of cardiac death tended to be higher in patients with ACS compared to those with stable ischemic syndromes randomized to the TAXUS stent. The rates of MI at one-year follow-up were similar between the two groups, as was TVR and MACE. Binary analysis segment restenosis rates in patients treated with the TAXUS stent were 5.0% in patients with ACS compared to 9.5% in non-ACS (p = 0.25). Analysis segment late loss after TAXUS stent placement also did not differ significantly between patients with and without ACS (0.19 ± 0.41 mm vs. 0.25 ± 0.45 mm, respectively, p = 0.23). By multivariate analysis, presentation with ACS was an independent predictor of freedom fromrestenosis among patients randomized to the TAXUS stent (HR = 0.27 [95% CI 0.08 to 0.97], p = 0.044).
Bare-metal stent arm: patients with stable versus unstable ischemic syndromes
The baseline characteristics of patients with versus without ACS treated with bare-metal stents differed in a similar fashion as for this comparison with paclitaxel-eluting stents. Compared with the 213 patients with ACS treated with bare-metal stents, the 439 patients with stable ischemic syndromes treated with the bare-metal stent had similar rates of stent thrombosis at 30 days (0.5% vs. 0.7%, respectively, p = 0.74) and 1 year (0.9% vs. 0.7%, respectively, p = 0.73). As seen in Figure 2, the rates of cardiac death, MI, TVR, and MACE were also not significantly different at one year. Binary restenosis in the analysis segment occurred in 21.7% in patients with ACS compared to 30.2% in patients without ACS treated with bare-metal stents (p = 0.13). Analysis segment late loss also did not differ significantly between the patients with and without ACS treated with bare-metal stents (0.69 ± 0.56 mm vs. 0.58 ± 0.58 mm, respectively, p = 0.15). By multivariate analysis, among patients randomized to the bare-metal control stent, the presence of ACS at baseline was an independent predictor of restenosis (HR = 2.03 [95% CI 1.05 to 3.92], p = 0.035).
The major results of this analysis from the TAXUS-IV randomized trial are: 1) implantation of the polymer-based paclitaxel-eluting TAXUS stent in ACS was safe, without increased rates of cardiac death, MI, or stent thrombosis compared to bare-metal stent implantation; 2) TAXUS stent implantation in patients with both ACS and non-ACS was associated with a marked reduction in clinical restenosis (TLR), with enhanced event-free survival compared to patients receiving a bare-metal stent; and 3) the TAXUS stent resulted in significant reductions in neointimal tissue proliferation and restenosis regardless of clinical syndrome acuity.
The thrombogenic coronary milieu in patients with unstable angina (12,14), coupled with a theoretical propensity for hypercoagulability and delayed re-endothelialization with drug-eluting stents, has resulted in concerns of an increased risk of stent thrombosis after implantation of these devices in patients with ACS. In this regard, a trend was present for an increased rate of stent thrombosis with the paclitaxel-eluting stent at 30 days in patients with unstable compared to stable ischemic syndromes in the present study. However, this difference represented two such events in the TAXUS arm versus zero in the control arm, and no such difference was present at one year. Moreover, there were no differences in stent thrombosis rates between patients treated with paclitaxel-eluting versus bare-metal stents within the cohort with ACS at any time period, nor were rates of MI or mortality increased with the paclitaxel-eluting stent compared to control in patients with ACS. Thus, from the available data, implantation of the TAXUS stent appears to be safe in both patients with stable and unstable ischemic syndromes, though additional studies with greater numbers of TAXUS implants in ACS are warranted, especially in patients excluded from randomization, such as those with acute ST-segment elevation MI and angiographically evident thrombus.
Similar to patients with stable ischemic syndromes, the use of paclitaxel-eluting stents in patients with ACS resulted in strikingly reduced rates of nine-month TLR (74% vs. 72%; p = 0.50), TVR (65% vs. 54%; p = 0.63), and angiographic restenosis (58% vs. 85%; p = 0.03). Notably, in patients with ACS, the TVR rate in patients treated with the TAXUS stent was almost unchanged from nine months (6.1%) to one year (6.5%), whereas the TVR rate continued to increase during this period in patients treated with bare-metal stents (from 13.2% to 17.7%, respectively). Similarly, the composite MACE rate was stable between nine months and one year (10.6% vs. 11.1%), but continued to increase in patients treated with bare-metal stents (from 16.4% to 21.7%). Of note, a numerically higher incidence of MI in addition to more revascularization procedures contributed to the incremental rise in adverse events in patients treated with bare-metal stents. Thus, the benefits of the TAXUS stent relative to the bare-metal control in patients with ACS are increasing with longer duration of follow-up (as previously described in the entire study population ).
Several prior studies have identified unstable angina as a risk factor for restenosis after bare-metal stent implantation (6,7). Major adverse cardiac events after bare-metal stenting are also increased in patients presenting with ACS compared to stable angina (16). In the present study, however, early and late TVR and MACE rates were similar in patients with and without ACS. Of interest, however, ACS was an independent predictor of in-stent restenosis in the cohort treated with bare-metal stents, whereas the presence of ACS was paradoxically an independent correlate of a reducedrisk of restenosis in patients treated with the TAXUS stent. The local influence of paclitaxel in reducing both inflammatory and proliferative responses might account for more pronounced beneficial effects of this device in patients with unstable compared with stable angina (17). Additional studies are required to confirm this possibility.
This post-hoc analysis was not pre-specified in the original trial design and, thus, must be considered hypothesis-generating. No conclusions can be drawn regarding patients excluded from randomization, including those with a CK-MB level >2 × the upper limits of normal at the time of the index PCI, angiographic evidence of definite thrombus, and acute ST-segment elevation MI, all of which are risk factors for adverse outcomes (18). The extent to which the prolonged (at least six-month) course of thienopyridines contributed to the beneficial outcomes in patients with ACS in the present study is unknown (19,20). Inflammatory biomarkers as well as cardiac enzymes other than creatine phosphokinase isoenzymes were not routinely collected, nor were admission electrocardiograms analyzed at a core laboratory; in-depth risk stratification of the patients was, therefore, not possible. Nonetheless, more than 65% of the patients with ACS were Braunwald class II or III, indicating high risk (21). The results of the present study are, therefore, applicable to the majority of patients with ACS, excepting those at the highest risk.
Conclusions and clinical implications
In this substudy of the TAXUS-IV randomized trial, the use of the paclitaxel-eluting TAXUS stent was safe in most patients with ACS, and was associated with markedly reduced ischemia-driven TLR, TVR, and MACE at one year. Thus, patients with ACS who otherwise meet the inclusion criteria for the TAXUS-IV study will have superior outcomes with preferential implantation of the polymer-based, paclitaxel-eluting stent rather than its bare-metal counterpart.
- Abbreviations and acronyms
- acute coronary syndrome
- confidence interval
- creatine kinase
- hazard ratio
- major adverse cardiac events
- myocardial infarction
- percutaneous coronary intervention
- target lesion revascularization
- target vessel revascularization
- Received June 28, 2004.
- Revision received October 18, 2004.
- Accepted October 25, 2004.
- American College of Cardiology Foundation
- Braunwald E.,
- Antman E.M.,
- Beasley J.W.,
- et al.,
- American College of Cardiology,
- American Heart Association,
- Committee on the Management of Patients with Unstable Angina
- Cannon C.P.,
- Weintraub W.S.,
- Demopoulos L.A.,
- et al.,
- TACTICS (Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative Strategy)-Thrombolysis In Myocardial Infarction 18 Investigators
- Boersma E.,
- Akkerhuis K.M.,
- Theroux P.,
- Califf R.M.,
- Topol E.J.,
- Simoons M.L.
- Odell A.,
- Gudnason T.,
- Andersson T.,
- Jidbratt H.,
- Grip L.
- de Groote P.,
- Bauters C.,
- McFadden E.P.,
- Lablanche J.M.,
- Leroy F.,
- Bertrand M.E.
- Morice M.C.,
- Serruys P.W.,
- Sousa J.E.,
- et al.,
- RAVEL Study Group
- Hamm C.W.,
- Braunwald E.
- Clarkson P.B.,
- Halim M.,
- Ray K.K.,
- et al.
- Stone G.W.,
- Ellis S.G.,
- Cox D.A.,
- et al.
- Stone G.W.,
- Moliterno D.J.,
- Bertrand M.,
- et al.
- Axel D.I.,
- Kunert W.,
- Goggelmann C.,
- et al.
- Diderholm E.,
- Andren B.,
- Frostfeldt G.,
- et al.,
- Fast Revascularisation during InStability in Coronary artery disease (FRISC II) Investigators
- Peters R.J.,
- Mehta S.R.,
- Fox K.A.,
- et al.,
- Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) Trial Investigators
- Steinhubl S.R.,
- Berger P.B.,
- Mann J.T. 3rd.,
- et al.,
- CREDO Investigators