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Catheter-Based Aortic Valve Replacement Equal to Surgery in High Risk Patients
Edwards SAPIEN Transcatheter heart valve
Edwards SAPIEN
Transcatheter Heart Valve

April 3, 2011 -- The much-anticipated findings from the PARTNER trial, comparing the standard surgical procedure of aortic valve replacement (AVR) to the newer and, as of yet, unapproved in the U.S. transcatheter-based version (TAVR), were presented today at the American College of Cardiology's 60th Annual Scientific Session in New Orleans -- and the two methods of treatment were judged virtually equivalent at one year.

The study reported results from "Cohort A" of the PARTNER trial which randomized patients who were at high risk for surgery either to the tried-and-true surgical approach or to treatment with the SAPIEN valve, manufactured by Edwards Lifesciences (NYSE: EW ), which is delivered via catheter, usually via the femoral artery.

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Drug-Eluting Stent Center

From Angioplasty and Stents to Aortic Valve Replacement
-- Editor's Blog

Transcatheter aortic valve replacement is an extension of the multiple therapies that have grown out of the field of interventional cardiology, started over three decades ago by Andreas Gruentzig with the first coronary angioplasty. At that time, surgeons were strongly opposed to this new unproven technology, but with the significant technical advances that have occurred over time, angioplasty and stenting have made a major impact on the treatment of coronary artery disease.

Which brings us to PARTNER, so-named because the exploration of this new therapy was done via a strong partnership between surgeons and interventional cardiologists. The PARTNER study was in fact presented by principal investigator Dr. Craig Smith, Chairman of the Department of Surgery at Columbia University -- and the co-investigator was Dr. Martin B. Leon, also of Columbia, who, as founder of the annual TCT meeting, is one of the foremost proponents of catheter-based treatment of heart disease.

So the future of this therapy is one that is adjudicated by both surgical and interventional physicians.

Primary Endpoints Equivalent with Some Caveats
The primary endpoint of Cohort A was freedom from death at one-year -- and the results were identical between the surgical and catheter-based arms: 26.8% for the surgical arm and 24.2% for the catheter-based arm -- statistically insignificant, given the total number of 699 patients.

Where the data did diverge was in the stroke rate (2.4% for surgery vs. 5.1% for catheter-based TAVR at one year), in major bleeding (19.5% for surgery vs. 9.3% for TAVR), and in vascular complications (3.2% for surgery vs. 11% for TAVR).

What is important to understand is that this trial measured a brand-new first generation transcatheter device against a surgical procedure which has been utilized for many years. And since the start of the PARTNER Trial, significant changes to the transcatheter device have been made. As Dr. John Webb of St. Paul's Hospital in Vancouver, BC, stated on

"This is a trial of a first-generation transcatheter-valve system, and with operators, many of whom had only done two cases before doing this trial, compared with the very best surgeons, at the very best sites in the United States -- a very high bar. And [the patients enrolled] were really just the top 10% of surgical candidates—the worst patients. Despite that, you have a mortality rate that's lower [numerically] with transcatheter-valve implantation. The study was powered as a noninferiority trial, and it met that benchmark."

Last fall, the results from cohort B were presented at the TCT annual meeting -- these were patients who were judged as too sick for surgery. So these patients were randomized to best medical therapy or TAVR -- and TAVR showed a 46% relative risk reduction in mortality over medical therapy. So for patients too sick for surgery, TAVR is clearly a better therapy -- and for patients at high risk for surgery, TAVR is equivalent.

The Future of TAVR
Time will tell, of course, whether the transcatheter valve is as durable as the surgical implant. One concern is whether the transcatheter valve is more prone to leaks. Surgical valves have been studied for many years, and currently the transcatheter valve studies cover two or three years at most.

However, for the populations studied in cohorts A and B, the TAVR procedure has fared well and Edwards Lifesciences is anticipating FDA approval for cohort B-type patients later this year.

Medtronic is also a player in this space, with their CoreValve device, currently approved in Europe. Even though the PARTNER Trial was done by their chief competitor, Medtronic today issued the following statement:

"Medtronic welcomes the findings released today on the Partner Cohort A, which demonstrate the clinical benefit of transcatheter aortic valve implantation (TAVI) therapy in select patients with aortic stenosis. TAVI studies – including both the Partner and the CoreValve U.S, Pivotal trials – address the needs of an under-served patient population that today has only one clinically-effective treatment option, surgical valve replacement.

The results of the Partner study show in particular that the outcomes of TAVI therapy are similar to those of surgical replacement in high-risk patients. TAVI therapy is therefore a viable alternative to surgical replacement for this patient group. CoreValve, which is a self-expanding valve with an 18 Fr platform, has been implanted in more than 15,000 patients worldwide; the Partner A results are consistent with the CoreValve worldwide clinical experience in high and extreme risk patients. Medtronic is committed to delivering new treatment solutions and improving outcomes for Americans with severe aortic stenosis. The Medtronic CoreValve U.S. Pivotal Trial– in partnership with 40 leading U.S. medical centers – is a critical step toward making this a reality. To date, 35 centers have been activated in the trial and patient enrollment is ongoing."

One of the significant differences between surgery and transcatheter procedures was the vascular complication rate (injury to and needed repair of the femoral artery) which was four-fold in the transcatheter arm. The first generation valve required a 24F arterial opening, which is quite large. The newer devices from Edwards and Medtronic only require an 18F opening, 25% smaller.

Cost-Effectiveness of TAVR
According to various financial analysts, TAVR (if validated) may reach a billion dollar industry in just a few years. But more importantly, it may make available a therapy that will extend life for patients too sick for surgery. In a separate presentation today, a study sponsored by Edwards and performed by the Harvard Clinical Research Institute (HCRI) in collaboration with the Saint Luke's Mid America Heart and Vascular Institute, found that TAVR was also cost-effective.

Matthew R. Reynolds, M.D., M.Sc., Director of the Economics and Quality of Life Research Center at HCRI, stated that:

"For these patients who are not candidates for surgery, transcatheter aortic valve replacement significantly increases life expectancy at an incremental cost per life year gained well within the range of other commonly utilized cardiovascular technologies."

Reported by Burt Cohen, April 3, 2011