Stent Thrombosis Risk Lower with Xience vs. First-Generation DES

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Newer-generation everolimus-eluting stents (EES) are associated with a lower risk of stent thrombosis—in particular very late stent thrombosis—compared with older sirolimus- and paclitaxel-eluting stents (SES and PES), according to observational data published online February 1, 2012, ahead of print in Circulation.

For the prospective study, Stephan Windecker, MD, of Bern University Hospital (Bern, Switzerland), and colleagues analyzed data from 12,339 patients implanted with EES (n = 4,212; Xience V, Abbott Vascular, Santa Clara, CA; or Promus, Boston Scientific, Natick, MA), SES (n = 3,819; Cypher, Cordis/Johnson and Johnson, Warren, NJ), or PES (n = 4,308; Taxus Express or Liberté, Boston Scientific) at 2 hospitals in the Netherlands and Switzerland. Patients who received EES were treated between November 1, 2006 and March 31, 2009, while those who received SES and PES were treated from April 16, 2002 to December 31, 2005.

Mean follow-up was 2.5 years for EES patients, 4 years for SES patients, and 3 years for PES patients, with an accumulated 9,519, 12,478, and 10,795 patient-years, respectively.

Xience Bests Taxus and Cypher

The overall incidence rate per 100 person-years of the primary endpoint, Academic Research Consortium (ARC)-defined definite stent thrombosis, was lower in the EES cohort (1.4 per 100 person-years) than with SES (2.9; HR 0.41; 95% CI 0.27-0.62; P < 0.0001) and PES (4.4; HR 0.33; 95% CI 0.23-0.48; P < 0.0001). EES-treated patients showed a lower risk for all categories of stent thrombosis—early (0-30 days), late (31-360 days), and very late (> 360 days)—but the difference was most pronounced for very late events, with a 67% risk reduction vs. SES and a 76% reduction vs. PES (table 1).

Table 1. Adjusted Definite Stent Thrombosis Risk up to 4 Years

Additionally, incidence rates were consistently lower for the secondary endpoint of ARC-defined definite or probable stent thrombosis overall and beyond 1 year (table 2).

Table 2. Adjusted Definite/Probable Stent Thrombosis Risk up to 4 Years

Importantly, the rate of cardiac death or MI was reduced for EES compared with PES (HR 0.65; 95% CI 0.56-0.75; P < 0.0001), which was directly related to the lower risk of stent thrombosis (HR 0.36; 95 CI 0.23-0.57).

‘Reassuring’ Despite Limitations

Due to the nonrandomized nature of the study, there are a number of potential limitations, Dr. Windecker and colleagues point out. For example:

• The varying lengths of dual antiplatelet therapy prescribed throughout the study may have had an impact on EES success. However, they note, whether prolonged dual antiplatelet therapy effectively prevents very late stent thrombosis is unknown

• The differing lengths of follow-up between the cohorts could also have confounded the findings
• General improvements to interventional treatment strategies over time may have contributed to an improved outcome with EES

 

Despite these limitations, Ajay J. Kirtane, MD, SM, of Columbia University Medical Center (New York, NY), told TCTMD in a telephone interview that this study “should buttress findings” from recent randomized and nonrandomized studies suggesting that EES are superior to their predecessors.

“Overall, [the study] should be pretty reassuring for physicians because, at least in the United States, the use of the everolimus-eluting stent has largely supplanted the use of the first-generation stents,” he said.

He added that the first-generation stents used in the study were not designed in a way to both maximize results and minimize complications.

“Basically both Cypher and Taxus were older stent platforms, with polymers that weren’t necessarily designed for biocompatibility,” he said. “And as a result they were very, very clinically effective in terms of reducing restenosis, but some of the safety issues needed to be worked out. [These] data in conjunction with some of the randomized data show that we do have a superior product compared to the first generation of drug-eluting stents.”

A ‘New Bar’ Set

In an accompanying editorial, Donald E. Cutlip, MD, of Beth Israel Deaconess Medical Center (Boston, MA), writes that, even with the limitations, “in the quest for the ‘holy grail’ in [PCI], namely a therapy with low rates of both restenosis and stent thrombosis, the data from [this study] provide convincing evidence that a device has emerged which allows discussion of this possibility…Taken together with other studies that have demonstrated at least equivalent efficacy, it appears a new bar has been set for PCI treatment of coronary artery disease.”

Dr. Cutlip emphasized, however, that “even the best PCI treatment is only truly safe and effective with appropriate use,” and researchers must strive for an “even safer and more effective percutaneous option.”

“As we move forward, the field should be congratulated for the process of innovation and development that when faced with a problem seeks solutions and then tests them rigorously,” he concluded. “Once again the future appears bright. This time our response should be one that tempers enthusiasm with recognition of limitations and a passion to be even better.”

Study Details

All patients received a loading dose of clopidogrel 300 mg to 600 mg during the procedure and were prescribed lifelong aspirin once daily. The duration of clopidogrel in the study differed according to the institution and the stent used, varying from 3 to 12 months after stenting.

Patients treated with EES compared with either SES or PES were older, more frequently hypertensive, less frequently smokers, had a lower LVEF, and presented more frequently with STEMI and cardiogenic shock. Patients treated with EES compared with those treated with PES had a higher BMI, and were more often diabetic and dyslipidemic. 

 

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Sources:
1. Räber L, Magro M, Stefanini GG, et al. Very late coronary stent thrombosis of a newer generation everolimus-eluting stent compared with early generation drug-eluting stents: A prospective cohort study. Circulation. 2012;Epub ahead of print.

2. Cutlip DE. Evidence of safety and effectiveness for a drug-eluting stent: How should we respond this time? Circulation. 2012;Epub ahead of print.

 

 

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