PARIS, France—In a real-world population, percutaneous coronary intervention (PCI) with newer-generation drug-eluting stents (DES) significantly reduces the risk of restenosis and stent thrombosis compared with first-generation DES at 2 years. Moreover, both generations increase survival compared with bare-metal stents (BMS), according to data presented August 29, 2011, at the European Society of Cardiology Congress.

Although many studies support the early and mid-term safety and efficacy of first-generation DES, there remains lingering concern over their long-term safety in everyday practice, especially with regard to the potential risk of late stent thrombosis, observed Giovanna Sarno, MD, PhD, of Uppsala University (Uppsala, Sweden). And little data are available regarding the long-term results from unrestricted use of new-generation stents, she added.

Comparing Stent Classes, Generations

To compare long-term outcomes for the different stent types and generations, Dr. Sarno and colleagues looked at data from 61,351 patients at 29 centers enrolled in the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) between November 2006 and October 2010.

Analyses were based on the type of stent implanted at the first recorded procedure. Only stent types implanted more than 500 times during the study period were included.

Patients were stratified into groups according to whether they received BMS (n = 42,773), old-generation DES (n = 12,153), or new-generation DES (n = 6,425).

Old-generation DES included Cypher and Cypher Select (Cordis/Johnson & Johnson, Miami Lakes, FL), and Taxus Express and Taxus Liberte (Boston Scientific, Natick, MA).

New-generation DES included:

• Resolute (Medtronic, Santa Rosa, CA)
• Xience V, Xience Prime (Abbott Vascular, Santa Clara, CA)
• Promus Element (Boston Scientific, Natick, MA)

In general, newer-generation stents feature thinner struts, more biocompatible polymers, cobalt- or platinum-chromium alloy platforms, and alternative antiproliferative agents like everolimus, biolimus, and zotarolimus, Dr. Sarno explained. She added that such features may give them an advantage in terms of deliverability, drug elution, endothelial coverage, and functional recovery.

There were some important differences in the distribution of baseline and angiographic characteristics between the stent types. For example, STEMI patients were more likely to receive BMS, while restenotic lesions and chronic total occlusions were more often treated with DES. Left main disease and Type C lesions also were more commonly treated with DES.

Over 2 years of follow-up, PCI with new-generation DES was associated with a 38% lower risk of restenosis and a 50% lower risk of stent thrombosis—the co-primary endpoints—compared with old-generation DES. Moreover, newer DES reduced mortality by 23% compared with older devices, and both generations of DES resulted in improved outcomes compared with BMS (table 1).

Table 1.Two-Year Cumulative Outcomes

Dr. Sarno noted that the stent thrombosis advantage of new- vs. old-generation DES appeared within the first month. Thereafter, the event rate for new devices increased slightly up to 12 months and then leveled off, while that for older DES rose steadily up to 2 years. 

In response to a question, she added that the high incidence of stent thrombosis seen with BMS was somewhat surprising, and may be due to the fact that these devices were typically given to STEMI patients, something clinicians now approach with more caution, she reported. Instead, BMS tend to be used only when the risk of restenosis is relatively low—eg, in the absence of diabetes or long lesions.

Dr. Sarno said further studies are needed to parse out which traits of the new-generation stents—eg, the polymer, the stent alloy, or the drug—are mainly responsible for the decreased incidence of restenosis and stent thrombosis.

Not Randomized—But Still Convincing

The study results need to be interpreted with caution, Dr. Sarno acknowledged, since they may be confounded by differences in baseline characteristics or selection criteria despite efforts to account for these factors.

Session cochair Elliott M. Antman, MD, of Brigham and Women’s Hospital (Boston, MA), observed that although the study is not randomized and does not have the benefit of propensity adjustment, the amount of confounding necessary to completely neutralize the observations would have to be overwhelming. “So I’m actually convinced that [the differences] we see here are probably correct, at least in relative terms,” he concluded.

Dr. Sarno said that large, randomized trials are needed to confirm that the newer-generation stents in fact benefit patients with a high-risk profile.

Disclosure:

Dr. Sarno reported no relevant conflicts of interest.

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