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TWENTE Published: New Medtronic Resolute Heart Stent Matches Abbott's Xience
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Medtronic Resolute and Abbott Xience V Stents
Medtronic Resolute and
Abbott Xience V Stents
February 15, 2012 -- The TWENTE clinical trial, comparing two second-generation drug-eluting stents, was published today as an expedited paper in the Journal of the American College of Cardiology. At one-year, the two stents, Medtronic's Resolute zotarolimus-eluting stent and Abbott's Xience V everolimus-eluting stent, had similar clinical outcomes in 1,391 "real-world" patients, randomized 1:1 to either stent. Angioplasty.Org previously reported on the TWENTE trial when it was presented in November at the TCT meeting in San Francisco.

In contrast to many of the initial clinical trials for stents, this trial enrolled 81.4% of the eligible patients with the only major exclusion being STEMI cases (ST-elevated myocardial infarction). As a result almost 80% of the patients were treated for what are technically "off-label" indications: more advanced coronary disease and complex anatomy; over half the patients presented with acute coronary syndome (ACS); 25% of the blockages were bifurcation lesions; 21% of the patients were diabetic. A total of 2,116 coronary blockages were treated.

Dr. Clemens von Birgelen
Dr. Clemens von Birgelen

All procedures were performed at Thoraxcentrum Twente in the Netherlands between June 2008 and August 2010. Clemens von Birgelen, MD, PHD, was Principal Investigator for TWENTE, which was an investigator-initiated study and was funded by equal unrestricted grants from both stent manufacturers, Abbott Vascular and Medtronic.

Dr. Birgelen noted in the paper that post-dilation, performed after the stent is initially implanted, was done in 82% of all cases. Post-dilation is a technique that utilizes intravascular ultrasound (IVUS) imaging to assure complete expansion of the stent struts. While this is the norm in his hospital, it is a very high rate compared to many institutions. Dr. Birgelen writes that:

"...liberal use of stent post-dilation to optimize stent apposition to the vessel wall...might facilitate drug delivery and could reduce stent thrombosis."

Results of TWENTE
The primary composite endpoint in this trial was the incidence of target vessel failure (TVF) within 1 year, defined as cardiac death, target vessel–related myocardial infarction (MI), or clinically driven target vessel revascularization (TVR) by re-PCI or surgery. TVF at one year occurred in 8.2% of patients for the zotarolimus-eluting stent, and in 8.1% of patients for the everolimus-eluting stent (p=0.94). For the components of the primary endpoint, there were also no significant differences: cardiac death (1.0% vs. 1.4%, p=0.46), target vessel-related myocardial infarction (4.6% vs. 4.6%, p=0.98), most of which occurred in the periprocedural period, and clinically driven target vessel revascularization (3.3% vs. 2.7%, p=0.53). Importantly, the one year followup was an impressive 100% (Dr. Birgelen told Angioplasty.Org that his staff actually traced patients to Asia and Africa to get this perfect followup figure).

The excellent results in this trial demonstrate clearly that, with the new, improved second-generation devices and careful technique, patient outcomes have improved significantly, with less need for re-intervention and greater safety: namely, increased incidence of late stent thrombosis with drug-eluting stents no longer seems to be a major issue. TWENTE showed similar and relatively low one-year rates of definite-plus-probable stent thrombosis for both the zotarolimus and everolimus-eluting stents (0.86% and 1.16%, respectively). TWENTE also showed a low definite one-year stent thrombosis rate for zotarolimus and everolimus-eluting stents (0.58% and 0%, respectively). These are encouraging numbers, especially considering the complexity of the patient population and the lesion characteristics.

Also encouraging is that the TWENTE trial results mirror those of the RESOLUTE ALL COMERS trial presented at last year's annual meeting of the American College of Cardiology.

Implications for the U.S. Stent Market
The Xience has virtually replaced the use of 1st generation DES in the United States with better outcomes and lower stent thrombosis rates. In fact, Johnson & Johnson/Cordis, the manufacturer of Cypher, the first FDA-approved drug-eluting stent, has exited the DES business entirely. While Xience has been marketed in the U.S. since July 2008, Medtronic's Resolute has been available in more than 50 countries in Europe, Asia, the Middle East and Africa since the end of 2007. Medtronic submitted its Resolute stent data to the FDA last year and, according to Medtronic spokesperson Joe McGrath, the company "continues to anticipate FDA approval of the Resolute Integrity Drug-Eluting Stent in the first half of 2012."

Assuming Resolute gains FDA approval, physicians in the U.S. will have a choice of two very similar stents and, as Dr. Ron Waksman of the Washington Hospital Center commented to Angioplasty.Org, physician choice may come down to pricing, availablility of stent sizes and personal preferences.

Reported by Burt Cohen, February 15, 2012