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PLATINUM: Novel Platinum-Chromium DES Equals Outcomes of Xience V-Promus

By L.A. McKeown

An everolimus-eluting stent with a novel platinum chromium-alloy platform is clinically noninferior to a currently available stent that releases the same drug from a cobalt chromium platform. The late-breaking trial results were presented April 4, 2011, at the American College of Cardiology Scientific Session/i2 Summit in New Orleans, LA, and simultaneously published online ahead of print in the Journal of the American College of Cardiology.

For the PLATINUM trial, researchers led by Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), enrolled 1,530 patients undergoing PCI of 1 or 2 de novo lesions in native coronary arteries at 132 international sites in 2009. Patients were randomized to receive either the new platinum chromium stent (Promus Element; n = 768) or a conventional cobalt chromium stent (Xience V/Promus; n = 762), both of which elute everolimus.

At 12 months, a per protocol analysis found that the rate of TLF (primary endpoint; composite of target vessel-related cardiac death, target vessel-related MI, or ischemia-driven TLR) was 2.9% with the cobalt chromium stent and 3.4% with the platinum chromium stent (P = 0.001 for noninferiority, P = 0.60 for superiority).

In the intent-to-treat analysis, there were no significant differences between the 2 stents in 12-month rates of TLF, cardiac death or MI, TLR, or Academic Research Consortium-defined definite or probable stent thrombosis (table 1).

Table 1. One-Year Outcomes

 

Cobalt Chromium
(n = 762)

Platinum
(n = 768)

P Value

TLF

3.2%

3.5%

0.72

Cardiac Death or MI

2.5%

2.0%

0.56

TLR

1.9%

1.9%

0.96

Stent Thrombosis

0.4%

0.4%

1.00


Unique Properties Drive Favorable Results

The new platinum chromium Promus Element stent (Boston Scientific, Natick, MA), uses the same durable, biocompatible, inert fluorocopolymer and antiproliferative agent as the control cobalt chromium Xience V/Promus stent (Abbott Vascular, Santa Clara, CA; Boston Scientific) but with a modified scaffold designed to provide improved deliverability, vessel conformability, side-branch access, radiopacity, radial strength, and fracture resistance.

Earlier studies of the cobalt chromium Xience stent indicate that its favorable results likely stem from the properties of its 3 main components: the polymer, the drug, and the metallic stent itself.

According to Dr. Stone and colleagues, its thin (7 µm), nonadhesive, durable and inert biocompatible fluorocopolymer appears resistant to platelet and thrombus deposition in blood-contact applications, possibly contributing to resistance to stent thrombosis. In addition, the polymer controls the release kinetics of the everolimus such that approximately 80% of the drug is released at 30 days, with none detectable after 120 days. The dose density of everolimus (100 µg/cm2) is lower than with any comparable rapamycin-analogue DES.

“Through use of a more dense platinum-chromium alloy and a modified scaffold architecture, the [newer stent] was developed to further improve upon several of the mechanical and physical properties of the [cobalt chromium everolimus-eluting stent],” they note.

Based on the current findings, “along with stainless steel and cobalt chromium, platinum chromium may now be considered an acceptable metal alloy for use in DES,” Dr. Stone and colleagues conclude.

 

Source:
Stone, MD GW, Teirstein PS, Meredith IT, et al. A prospective, randomized evaluation of a novel everolimus-eluting coronary stent: The PLATINUM (a prospective, randomized, multicenter trial to assess an everolimus-eluting coronary stent system [PROMUS Element] for the treatment of up to two de novo coronary artery lesions) trial. J Am Coll Cardiol. 2011;Epub ahead of print.

 

 

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Disclosures
  • Dr. Stone reports serving on the advisory boards of Abbott Vascular and Boston Scientific.

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