PARIS, France—Everolimus-eluting stents curb the risk of very late stent thrombosis compared with first-generation drug-eluting stents (DES) in an all-comers population, also outperforming bare-metal stents (BMS) in terms of repeat revascularization and stent thrombosis in patients with ST-segment elevation myocardial infarction (STEMI). The results from 2 trials presented Tuesday, August 30, at the European Society of Cardiology Congress 2011, are the latest round of evidence backing the second-generation device.

Bern-Rotterdam Cohort Study

To test whether a newer generation DES might reduce long-term stent thrombosis risk, Lorenz Räber, MD, of Bern University Hospital (Bern, Switzerland), and colleagues documented the experience of 12,339 consecutive patients treated at that institution and at the Thoraxcenter (Rotterdam, The Netherlands) with:

• Xience V everolimus-eluting stents (EES; n = 4,212; Abbott Vascular, Santa Clara, CA)
• Cypher sirolimus-eluting stents (SES; n = 3,819; Cordis/Johnson & Johnson, Bridgewater, NJ)
• Taxus Express paclitaxel-eluting stents (PES; n = 4,308; Boston Scientific, Natick, MA)

Subjects were enrolled between March 2002 and March 2009. All had stenoses greater than 50%, and indications included stable angina, silent ischemia, and ACS. There were no exclusions related to the number of lesions or vessels treated or to lesion length.

Before or during each procedure, patients received aspirin (≥ 100 mg), clopidogrel (loading dose 300-600 mg), and unfractionated heparin (intravenous bolus of ≥ 5,000 IU or 70 IU/kg). Glycoprotein IIb/IIIa inhibitors were administered at operator discretion. After PCI, patients were given aspirin indefinitely (100 mg/day) and clopidogrel for 3 to 12 months (75 mg/day).

By 4 years, the primary endpoint of Academic Research Consortium-defined definite stent thrombosis had occurred in 4.4% of PES, 2.9% of SES, and 1.4% of EES patients. Further calculations found that EES reduced the likelihood of such events by 59% compared with SES and by 67% compared with PES (table 1).

Table 1. Risk of Definite Stent Thrombosis at 4 Years

In particular, very late stent thrombosis (1-4 years) also was lower with EES vs. SES (HR 0.33; 95% CI 0.15-0.72; P = 0.006) and vs. PES (HR 0.24; 95% CI 0.13-0.47; P < 0.0001).

Clinical outcomes favored the newer stent, with cardiac death or MI occurring in 11% of EES patients, 11.7% of SES patients (P = 0.09 vs. EES), and 14.6% of PES patients (P < 0.0001 vs. EES).

“The strength of this study of the Bern-Rotterdam cohort is that it reflects an all-comers population. This cohort achieves a high degree of generalizability to general practice,” Dr. Räber said but cautioned that the study was nonrandomized and observational. Moreover, he noted, “patients were enrolled sequentially and advances in implantation technique and prolongation of dual antiplatelet therapy to 1 year may have favored EES.”

That being said, “the reduced risk of very late stent thrombosis with the unrestricted use of EES overcomes the principal limitation of early generation DES and constitutes an important advance in DES safety,” Dr. Räber concluded.

The everolimus stent offers better outcomes in terms of late stent thrombosis because of the condition’s underlying cause, Dr. Räber explained in a telephone interview. “Reasons for early stent thrombosis are related to the procedure itself, whereas late stent thrombosis is a distinct entity, and actually related to impaired healing, resulting in stent noncoverage and an inflammatory reaction,” he said.

EXAMINATION of Everolimus vs. Bare Metal

The EXAMINATION trial (a clinical Evaluation of Xience-V stent in Acute Myocardial INfArcTION), presented by Manel Sabaté, MD, PhD, of Hospital Clínic (Barcelona, Spain), also investigated Xience V stents, this time compared with Vision cobalt-chromium BMS (Abbott Vascular). STEMI patients who presented within 48 hours and required emergent PCI were randomized to EES (n = 751) or BMS (n = 747). Covering 70% of all STEMI patients who presented at the study’s 12 participating centers, the cohort included subjects needing rescue PCI as well as treatment after successful thrombolysis.

At 1 year, survival from all-cause death, any MI, or any revascularization (primary endpoint) was similar between the 2 treatment arms, as was survival from cardiac death and freedom from recurrent MI. However, EES patients were less likely to need TLR or TVR, or to experience definite stent thrombosis, compared with BMS patients (table 2).

Table 2. Freedom from Events at 1 Year

“With this trial, we’re able to apply our findings from EXAMINATION to most patients arriving in the hospital,” Dr. Sabaté said, adding, “We didn’t reach the primary endpoint, but the secondary endpoints are extremely significant.”

He concluded: “These finding support the safety and efficacy profile of the Xience V stent in a widely representative cohort of patients presenting with STEMI.”

 

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Sources:
1. Räber L. Bern-Rotterdam Cohort Study: Newer generation everolimus-eluting stents eliminate the risk of very late stent thrombosis compared with early generation sirolimus-eluting and paclitaxel-eluting stents. Presented at: European Society Cardiology Congress; August 30, 2011; Paris, France.

2. Sabaté M. The EXAMINATION (a clinical Evaluation of Xience V stent in Acute Myocardial INfArcTION) trial. Presented at: European Society Cardiology Congress; August 30, 2011; Paris, France.

 

 

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