ATLANTA -- Two new stent designs appear at least as safe as prior generations with some efficacy advantages, according to trials reported here at the American College of Cardiology.
A novel dual drug-eluting, polymer-free stent appeared as safe as the first generation sirolimus-eluting Cypher and second-generation zotarolimus-eluting Endeavor stents over the mid-term, from one to two years (P=0.61 for death or MI and P=NS for definite stent thrombosis).
Action Points
- Note that these studies were published as abstracts and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
The new stent also had the lowest two-year rates for target vessel revascularization (7.7% versus 10.7% Cypher and 14.3% Endeavor), and for binary restenosis (13.9% versus 18.8% and 20.9%, respectively), according Robert A. Byrne, MBBCh, MRCPI, of Technische Universitat in Munich, Germany, and colleagues.
Some stents look better than others at the beginning of trials but as the drug wears off, they may produce additional thrombosis -- a so-called "catch-up effect" that typically occurs between years one and two.
For both binary restenosis and revascularization, the late "catch-up" for the novel stent in the ISAR TEST 2 study fell between Cypher (P=0.016 and P=0.009) and Endeavor (P=0.28 and P=0.72).
The durable advantage in anti-restenotic efficacy might be due to the elimination of polymer from the stent, since an inflammatory response to polymer residue may play a central role in delayed arterial healing and thus late stent thrombosis, Byrne told the ACC.
However, it's hard to sort out which element produced the differences because the novel stent also eluted the antioxidant probucol, in addition to sirolimus, noted study discussant Laura Mauri, MD, MSc, of Harvard and Brigham and Women's Hospital in Boston.
Byrne acknowledged probucol's "checkered past" when given systemically, noting that it's better suited to local tissue administration.
Mauri cautioned, too, that only 493 of the originally randomized 1,007 patients got two-year angiographic follow-up -- an insufficient number to prove equivalent safety.
In a separate study, the new generation of paclitaxel-eluting stent with a novel platinum chromium, thin-strut structure (Taxus Element) was not inferior to the first-generation paclitaxel-eluting stent (Taxus Express).
Comparison with the bare-metal Taxus Express stent showed the novel design was more effective for small caliber vessels in results presented by Dean J. Kereiakes, MD, of the Christ Hospital Heart and Vascular Center in Cincinnati.
Since there aren't many stents that address small vessels, that may be an attractive feature, according to past AHA president Alice Jacobs, MD, of Boston University.
However, she cautioned that comparison of Taxus stents and other types has not favored Taxus.
The new design provides greater strength, flexibility, radiopacity, and uniform drug distribution than the prior Taxus generations while reducing recoil and nickel content, Kereiakes said.
His group's pivotal PERSEUS trial randomized 1,262 patients with target vessels of 2.75 to 4.0 mm diameter and 28 mm or shorter length to get the Taxus Express or Element stent.
Procedural success was similar between groups.
The newer generation of stent met noninferiority criteria for both the primary endpoint of the composite rate of ischemia-driven target lesion revascularization and MI or cardiac death related to target vessel (difference -0.57%), and the secondary endpoint of quantitative coronary angiography (difference -0.03).
Late loss appeared to be slightly higher with the new platform on nine-month angiography (0.34 versus 0.26 mm, P=0.33), but Mauri said this might have been explained by the higher acute gain. He noted, though, that the net results were similar between the two.
Twelve-month clinical outcomes also showed no significant differences, including stent thrombosis.
A parallel, small vessel comparison of the study included 224 patients with 2.25-to-2.75 mm diameter vessels that were 40 mm long or less who received the Element stent open-label, compared with 125 historical controls from the TAXUS V study who got the bare-metal Express stent (the only comparator at the time), Kereiakes said.
For the primary endpoint, the Element stent met superiority criteria for late loss (0.38 versus 0.80 mm, P<0.001 at nine months).
The secondary endpoint of the composite rate of ischemia-driven target lesion revascularization and MI or cardiac death related to target vessel was likewise improved with the new platform in these small vessels (P<0.001).
At 12 months, this remained true (P=0.01), while the major adverse cardiac event rate was one-third of that with the bare-metal comparator (P=0.002). Stent thrombosis rates were similar (0.3% versus 0.6%, P=0.65).
Disclosures
Byrne reported conflicts of interest with Medtronic and Biotronik.
The PERSEUS trials and Kereiakes' presentation were sponsored and funded by Boston Scientific.
Kereiakes reported conflicts of interest with REVA Medical, Medpace, Eli Lilly, Boston Scientific, Devax, Abbott Vascular, Amylin Pharmaceuticals, Medtronic, Abbott Vascular Solutions, Boston Scientific, Cordis/Johnson & Johnson, and Daiichi Sankyo.
Jacobs reported being a site primary investigator for a drug-eluting stent registry.
Mauri reported conflicts of interest with Cordis and Medtronic Vascular.
Primary Source
American College of Cardiology
Source Reference: Kereiakes DJ, et al "TAXUS PERSEUS: A novel platinum chromium, thin-strut TAXUS element stent for the treatment of de novo coronary stenoses" ACC 2010.
Secondary Source
American College of Cardiology
Source Reference: Byrne RA, et al "ISAR-TEST-2 trial: Two-year clinical and angiographic outcomes from a randomized trial of polymer-free dual drug-eluting stents versus polymer-based cypher and endeavor drug-eluting stents" ACC 2010.