Impact of the everolimus-eluting stent on stent thrombosis: a meta-analysis of 13 randomized trials

Prolonged clopidogrel use after bare metal and drug-eluting stent placement: the Veterans Administration drug-eluting stent study

BACKGROUND

Current guidelines recommend combining clopidogrel with aspirin for up to 1 year after coronary stenting, but the value of clopidogrel beyond this time is uncertain.

METHODS AND RESULTS

We evaluated all patients in the Veterans Administration healthcare system receiving either drug-eluting or bare metal stents from 2002 to 2006. The Veterans Administration National Patient Care and Pharmacy databases were used to extract patient characteristics, duration of clopidogrel use, and outcomes for up to 4 years after the index procedure. We used Cox proportional hazards to estimate hazard ratios for death, myocardial infarction, revascularization, and bleeding from a 12-month landmark after stenting that excluded patients with events within the first 12 months. Of 42,254 patients, 29,175 met the study inclusion criteria. Compared with ≤12 months of clopidogrel, prolonged clopidogrel (>12 months) was associated with a lower adjusted risk of death for both drug-eluting stents (hazard ratio [HR], 0.70; 95% confidence interval [CI], 0.61, 0.82; P<0.01) and bare metal stents (HR, 0.85; 95% CI, 0.76, 0.96; P=0.01) as well as for death and myocardial infarction but was unrelated to stroke or major bleeding. The effect of prolonged clopidogrel on death or myocardial infarction was significantly greater among patients receiving drug-eluting (HR, 0.70; 95% CI, 0.64, 0.84) compared with bare metal stents (HR, 0.88; 95% CI, 0.79, 0.98; interaction P=0.024).

CONCLUSIONS

Patients receiving clopidogrel beyond 12 months had a lower risk of death or myocardial infarction compared patients receiving clopidogrel ≤12 months. The risk reduction was greater for drug-eluting stents. These data support longer durations of dual antiplatelet therapy for patients receiving a stent, particularly for those receiving a drug-eluting stent.

Stent Thrombosis With Everolimus-Eluting Stents

Background—

Some but not all studies have reported reduced rates of stent thrombosis (ST) with everolimus-eluting stents (EES) compared with other drug-eluting stents (DES). All of these studies were insufficiently powered to reliably detect differences in ST. We therefore performed a meta-analysis of randomized controlled trials comparing the risk of 2-year definite ST between EES and other DES.

Methods and Results—

Randomized controlled trials comparing EES versus other DES were searched through MEDLINE, EMBASE, Cochrane databases, and proceedings of international meetings. Information on study design, inclusion and exclusion criteria, sample characteristics, and clinical outcomes was extracted. Eleven randomized controlled trials (16 775 patients) were analyzed, including 5 trials (n=7113) of EES versus paclitaxel-eluting stents, 5 trials (n=7370) of EES versus sirolimus-eluting stents, and 1 trial (n=2292) of EES versus zotarolimus-eluting stents. By 2 years definite ST with EES compared with pooled DES occurred in 0.5% versus 1.3% patients, respectively (relative risk, 0.38; 95% CI, 0.24–0.59; P <0.0001). Similar results were observed when the broader definition of definite/probable ST was considered (relative risk, 0.46; 95% CI, 0.33–0.66; P <0.0001). EES compared with other DES reduced the relative risk of early ST (within 30 days), late ST (31 days to 1 year), cumulative 1-year ST, and very late ST (1–2 years). The reduced rate of definite ST observed with EES was consistent across all DES comparators with no interactions apparent during any time interval.

Conclusions—

EES compared with a pooled group of paclitaxel-eluting stents, sirolimus-eluting stents, and zotarolimus-eluting stents is associated with a significant reduction of definite ST, an effect that appears early and increases in magnitude through at least 2 years.

The importance of the endothelium in atherothrombosis and coronary stenting

Deployment of drug-eluting stents instead of bare-metal stents has dramatically reduced restenosis rates, but rates of very late stent thrombosis (>1 year postimplantation) have increased. Vascular endothelial cells normally provide an efficient barrier against thrombosis, lipid uptake, and inflammation. However, endothelium that has regenerated after percutaneous coronary intervention is incompetent in terms of its integrity and function, with poorly formed cell junctions, reduced expression of antithrombotic molecules, and decreased nitric oxide production. Delayed arterial healing, characterized by poor endothelialization, is the primary cause of late (1 month-1 year postimplantation) and very late stent thrombosis following implantation of drug-eluting stents. Impairment of vasorelaxation in nonstented proximal and distal segments of stented coronary arteries is more severe with drug-eluting stents than bare-metal stents, and stent-induced flow disturbances resulting in complex spatiotemporal shear stress can also contribute to increased thrombogenicity and inflammation. The incompetent endothelium leads to late stent thrombosis and the development of in-stent neoatherosclerosis. The process of neoatherosclerosis occurs more rapidly, and more frequently, following deployment of drug-eluting stents than bare-metal stents. Improved understanding of vascular biology is crucial for all cardiologists, and particularly interventional cardiologists, as maintenance of a competently functioning endothelium is critical for long-term vascular health.

Safety and efficacy of the XIENCE V everolimus-eluting stent compared to first-generation drug-eluting stents in contemporary clinical practice

Data from randomized clinical trials have shown the safety and efficacy of the XIENCE V in selected populations. However, limited data are available comparing the XIENCE V to the first-generation CYPHER sirolimus-eluting stent. This study aimed to assess the long-term safety and clinical efficacy of the XIENCE V everolimus-eluting stent compared to first-generation stents in an unselected patient population. This retrospective analysis included 6,069 patients treated with CYPHER, TAXUS, and XIENCE stents from 2003 to 2009 at our institution. The patients were followed up for ≥1 year after the index procedure. The baseline characteristics were generally comparable among the 3 groups, with the exception of a significantly greater prevalence of diabetes mellitus, systemic hypertension, and a history of angioplasty and coronary bypass surgery among the XIENCE patients. The XIENCE patients also had a twofold greater rate of type C lesions. One-year follow-up data were available for 82% of the patients. The 1-year major adverse cardiovascular events rate was 9.3% for the XIENCE stent versus 9.8% for the CYPHER stent and 11.5% for the TAXUS stent (p = 0.11). Mortality was lower in the XIENCE group than in the CYPHER and TAXUS groups (3.6% vs 4.9% vs 7.2%, respectively, p <0.001), and target lesion revascularization was similar (5.9% vs 5.2% vs 5.6%, respectively; p = 0.34). Stent thrombosis was lower in the XIENCE patients (0.2% vs 1.2% vs 0.7%, p = 0.007). In conclusion, in a contemporary United States clinical practice with an unselected patient population, use of the XIENCE V stent was associated with an improved safety profile and reduction of all-cause mortality and stent thrombosis compared to first-generation drug-eluting stents. The XIENCE V failed to demonstrate superiority for overall major adverse cardiovascular events, Q-wave myocardial infarction, and revascularization rates.

The 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE) trial: study protocol for a randomized controlled trial

BACKGROUND

Second-generation drug-eluting stents (DES) have raised the bar of clinical performance. These stents are mostly made from cobalt chromium alloy. A newer generation DES has been developed from platinum chromium alloy, but clinical data regarding the efficacy and safety of the platinum chromium-based everolimus-eluting stent (PtCr-EES) is limited, with no comparison data against the cobalt chromium-based zotarolimus-eluting stent (CoCr-ZES). In addition, an antiplatelet regimen is an integral component of medical therapy after percutaneous coronary intervention (PCI). A 1-week duration of doubling the dose of clopidogrel (double-dose antiplatelet therapy (DDAT)) was shown to improve outcome at 1 month compared with conventional dose in acute coronary syndrome (ACS) patients undergoing PCI. However in Asia, including Korea, the addition of cilostazol (triplet antiplatelet therapy (TAT)) is used more commonly than doubling the dose of clopidogrel in high-risk patients.

METHODS

In the 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE) trial, approximately 3,750 patients are being prospectively and randomly assigned in a 2 × 2 factorial design according to the type of stent (PtCr-EES vs CoCr-ZES) and antiplatelet regimen (TAT vs DDAT). The first primary endpoint is target lesion failure at 1 year for the stent comparison, and the second primary endpoint is net clinical outcome at 1 month for comparison of antiplatelet therapy regimen.

DISCUSSION

The HOST-ASSURE trial is the largest study yet performed to directly compare the efficacy and safety of the PtCr-EES versus CoCr-ZES in an 'all-comers' population. In addition, this study will also compare the clinical outcome of TAT versus DDAT for 1-month post PCI.

TRIAL REGISTRATION

ClincalTrials.gov number NCT01267734.

A randomized controlled trial in second-generation zotarolimus-eluting Resolute stents versus everolimus-eluting Xience V stents in real-world patients: the TWENTE trial

OBJECTIVES

The aim of this study was to compare the safety and efficacy of Resolute zotarolimus-eluting stents (ZES) (Medtronic Cardiovascular, Santa Rosa, California) with Xience V everolimus-eluting stents (EES) (Abbott Vascular Devices, Santa Clara, California) at 1-year follow-up.

BACKGROUND

Only 1 randomized trial previously compared these stents.

METHODS

This investigator-initiated, patient-blinded, randomized noninferiority study had limited exclusion criteria (acute ST-segment elevation myocardial infarctions not eligible). Patients (n = 1,391; 81.4% of eligible population) were randomly assigned to ZES (n = 697) or EES (n = 694). Liberal use of stent post-dilation was encouraged. Cardiac biomarkers were systematically assessed. The primary endpoint was target vessel failure (TVF), a composite of cardiac death, myocardial infarction not clearly attributable to non-target vessels, and clinically indicated target-vessel revascularization. An external independent research organization performed clinical event adjudication (100% follow-up data available). Analysis was by intention-to-treat.

RESULTS

Acute coronary syndromes were present in 52% and "off-label" feature in 77% of patients. Of the lesions, 70% were type B2/C; the post-dilation rate was very high (82%). In ZES and EES, TVF occurred in 8.2% and 8.1%, respectively (absolute risk-difference 0.1%; 95% confidence interval: -2.8% to 3.0%, p(noninferiority) = 0.001). There was no significant between-group difference in TVF components. The definite-or-probable stent thrombosis rates were relatively low and similar for ZES and EES (0.9% and 1.2%, respectively, p = 0.59). Definite stent thrombosis rates were also low (0.58% and 0%, respectively, p = 0.12). In EES, probable stent thrombosis beyond day 8 was observed only in patients not adhering to dual antiplatelet therapy.

CONCLUSIONS

Resolute ZES were noninferior to Xience V EES in treating "real-world" patients with a vast majority of complex lesions and "off-label" indications for drug-eluting stents, which were implanted with liberal use of post-dilation. (The Real-World Endeavor Resolute Versus XIENCE V Drug-Eluting SteNt Study: Head-to-head Comparison of Clinical Outcome After Implantation of Second Generation Drug-eluting Stents in a Real World Scenario; NCT01066650).

Long-term clinical outcomes of biodegradable polymer biolimus-eluting stents versus durable polymer sirolimus-eluting stents in patients with coronary artery disease (LEADERS): 4 year follow-up of a randomised non-inferiority trial

BACKGROUND

The effectiveness of durable polymer drug-eluting stents comes at the expense of delayed arterial healing and subsequent late adverse events such as stent thrombosis (ST). We report the 4 year follow-up of an assessment of biodegradable polymer-based drug-eluting stents, which aim to improve safety by avoiding the persistent inflammatory stimulus of durable polymers.

METHODS

We did a multicentre, assessor-masked, non-inferiority trial. Between Nov 27, 2006, and May 18, 2007, patients aged 18 years or older with coronary artery disease were randomly allocated with a computer-generated sequence to receive either biodegradable polymer biolimus-eluting stents (BES) or durable polymer sirolimus-eluting stents (SES; 1:1 ratio). The primary endpoint was a composite of cardiac death, myocardial infarction, or clinically-indicated target vessel revascularisation (TVR); patients were followed-up for 4 years. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00389220.

FINDINGS

1707 patients with 2472 lesions were randomly allocated to receive either biodegradable polymer BES (857 patients, 1257 lesions) or durable polymer SES (850 patients, 1215 lesions). At 4 years, biodegradable polymer BES were non-inferior to durable polymer SES for the primary endpoint: 160 (18·7%) patients versus 192 (22·6%) patients (rate ratios [RR] 0·81, 95% CI 0·66-1·00, p for non-inferiority <0·0001, p for superiority=0·050). The RR of definite ST was 0·62 (0·35-1·08, p=0·09), which was largely attributable to a lower risk of very late definite ST between years 1 and 4 in the BES group than in the SES group (RR 0·20, 95% CI 0·06-0·67, p=0·004). Conversely, the RR of definite ST during the first year was 0·99 (0·51-1·95; p=0·98) and the test for interaction between RR of definite ST and time was positive (p(interaction)=0·017). We recorded an interaction with time for events associated with ST but not for other events. For primary endpoint events associated with ST, the RR was 0·86 (0·41-1·80) during the first year and 0·17 (0·04-0·78) during subsequent years (p(interaction)=0·049).

INTERPRETATION

Biodegradable polymer BES are non-inferior to durable polymer SES and, by reducing the risk of cardiac events associated with very late ST, might improve long-term clinical outcomes for up to 4 years compared with durable polymer SES.

FUNDING

Biosensors Europe SA, Switzerland.