Meta-analysis: Less Stent Thrombosis at 2 Years with EES vs. Other DES

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Everolimus-eluting stents (EES) confer a lower risk of stent thrombosis that begins early and increases in magnitude up to 2 years compared with first-generation drug-eluting stents (DES) as well as other second-generation devices that release zotarolimus, according to the results of a meta-analysis published online June 5, 2012, ahead of print in Circulation: Cardiovascular Interventions.

Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), and colleagues analyzed the results of 11 randomized controlled trials (n = 16,775) comparing Xience V (Abbott Vascular, Santa Clara, CA) and Promus EES (Boston Scientific, Natick, MA) with other DES:

  • Cypher sirolimus-eluting stents (SES; Cordis, Miami Lakes, FL)
  • Taxus Express and Liberté paclitaxel-eluting stents (PES; Boston Scientific, Natick, MA)
  • Endeavor phosphorylcholine-based zotarolimus-eluting stents (ZES; Medtronic, Santa Rosa, CA)
  • Resolute ZES (Medtronic)

Only 1 of the 11 trials compared EES with ZES. The primary endpoint was the 2-year rate of stent thrombosis as measured by the Academic Research Consortium criteria. Comparisons were made between EES and the pooled outcomes of DES, and also between EES and each of the DES comparators.

Consistently Decreased Stent Thrombosis

By 2 years, definite stent thrombosis had occurred in 0.5% of patients given EES compared with 1.3% of patients given any of the other stents, equating to a 62% reduced risk (P < 0.0001). When the researchers applied the broader definition of definite/probable stent thrombosis, a statistically significant difference in cumulative events remained, amounting to a 54% reduced risk (P < 0.0001). Early, late, and cumulative 1-year stent thromboses were also less likely in conjunction with EES use (table 1).

Table 1. Likelihood of Stent Thrombosis: EES vs. Other DES


RR (95% CI)

RR (95% CI)

Cumulative 2 Yeara

0.38 (0.24-0.59)

0.46 (0.33-0.66)

Early (30 days)

0.28 (0.15-0.53)

0.54 (0.35-0.83)

Late (31 days-1 year)

0.33 (0.15-0.70)

0.44 (0.25-0.80)

Cumulative 1 Year

0.28 (0.17-0.46)

0.51 (0.36-0.73)

a Primary endpoint.

The findings demonstrate “that differences in [stent thrombosis among] DES are not restricted to the late period after implantation but occur also in the early period,” the investigators write. “This observation suggests that optimizing DES components and performance is essential to minimize early as well as late [stent thrombosis], an important finding because early [events are more frequent than late].”

Complementary Data

In a telephone interview with TCTMD, David E. Kandzari, MD, of the Piedmont Heart Institute (Atlanta, GA), said that although there have been stents in the past that have been associated with favorable very late stent thrombosis, “this is really the first time that we are combining some of the best efficacy that we have ever seen with a DES with the best safety as well.”

Donald E. Cutlip, MD, of Beth Israel Deaconess Medical Center (Boston, MA), told TCTMD that this most recent meta-analysis does indeed add to existing evidence that shows that the risk for both early and very late stent thrombosis is decreased with EES, but added that the study should be interpreted carefully.

“Based on the methods used, EES [are associated with] lower stent thrombosis at all time points compared to first-generation PES and SES,” Dr. Cutlip said in a telephone interview. However, he added that with only 1 trial pitting EES against ZES, the evidence is not very strong and therefore more follow-up data are needed to draw any conclusions.

Bar Set High for Newcomers

Looking to the future, all 3 physicians said that the bar is now set very high for further reducing stent thrombosis with current or future devices.

Dr. Cutlip stressed that although EES are clearly superior to the first-generation stents, continued research comparing them with ZES and other future devices is of high importance. However, the very low event rates being seen will change how research is conducted. “Moving forward, it will take larger and larger clinical trials to look for differences or even similarity between devices,” Dr. Cutlip said. “It will make improving those stents even harder.”

In a telephone interview, Dr. Stone explained a possible mechanism for the EES advantage: “the fluoropolymer surface on the EES stent that affords its antithrombotic properties, and fluoropolymers are known to be very platelet- and thrombus-resistant. In contrast, newer stents are going in different directions.”

Some newer stents are incorporating bioabsorbable polymers and using smaller drug doses so that within 3 to 6 months the drug and the polymer are completely gone, leaving behind a BMS, while others stents are polymer-free or employ fully bioabsorbable vascular scaffolds.

“So because the new stent technologies have been developed to be able to reduce some of the stent thrombosis complications that may have been produced by the polymer and to improve long-term outcomes by eliminating the polymer—or in the case of the bioabsorbable vascular scaffold, the stent itself—the question becomes whether or not these new stents are going to be as or more successful than fluoropolymer-coated EES,” Dr. Stone concluded.

Note: Dr. Stone is a faculty member of the Cardiovascular Research Foundation, which owns and operates TCTMD.


Palmerini T, Kirtane AJ, Serruys PW, et al. Stent thrombosis with everolimus-eluting stents: meta-analysis of comparative randomized controlled trials. Circ Cardiovasc Interv. 2012;5:357-364.



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  • The meta-analysis was supported by the Cardiovascular Research Foundation with no external funding.
  • Dr. Stone reports serving as a consultant to Abbott Vascular, Boston Scientific, and Medtronic.
  • Dr. Cutlip reports serving as a principal investigator in the EDUCATE trial, sponsored by Medtronic.
  • Dr. Kandzari reports receiving consulting fees, honoraria, and/or research support from Abbott Vascular, Boston Scientific, Cordis, Covidien, Medtronic, Micell Technologies, and Terumo Medical.