WASHINGTON – A transcatheter pulmonary valve system that provides a new right ventricle to pulmonary artery conduit to congenital heart disease patients without the need for open heart surgery performed a little better in a real world registry at 10 U.S. centers than it had in the pivotal trial that led to the system’s 2010 FDA approval.
The new results "confirm the strong performance of the Melody transcatheter pulmonary valve achieved by real world providers with results comparable to the U.S. investigational device exemption [IDE] trial," Dr. Aimee K. Armstrong said at the annual meeting of the American College of Cardiology. The "high level" of 97% freedom from transcatheter pulmonary valve (TPV) dysfunction at 1 year "was better than in the IDE trial," where the level reached 94%, noted Dr. Armstrong, an interventional cardiologist in the pediatric cardiac catheterization laboratory at the University of Michigan in Ann Arbor.
The registry study, which the Food and Drug Administration mandated when it approved the Melody valve in 2010, ran during July 2010 to July 2012 at 10 U.S. centers that had not participated in the pivotal trial. The 99 patients who received an implant that stayed in place for at least 1 day ranged from 5 to 45 years old, with an average age of 20 years.
Although patient follow-up averaged 22 months, the study’s primary endpoint was acceptable hemodynamic function within the conduit at 6 months, with a prespecified performance goal of 75% of patients achieving this outcome. The outcome actually occurred in 97% of the 90 evaluable patients at 6 months, and in 88% of all 99 patients who received a conduit. The difference between each of these rates and the performance goal was statistically significant, Dr. Armstrong said.
The transcatheter valve showed excellent performance by other criteria as well. Acceptable hemodynamic function continued through 1 year in 94% of the 87 implanted patients with evaluable data at 12 months, which translated to 83% of the entire 99 patients in the implanted group. Severe or moderate pulmonary valve regurgitation existed in 85% of the patients before treatment; after treatment no patient had severe or moderate regurgitation, and after 1 year 63% had no regurgitation, 24% had trace, and 12% had mild regurgitation (figures total 99% because of rounding). The 1-year rate of 97% of patients free from dysfunction of their implanted valve appeared to surpass the 94% rate seen in the pivotal trial (Circulation 2010;122:507-16). Dr. Armstrong suggested that if this represented truly improved performance, it may have resulted from lessons during the prior trial on how to best deploy the transcatheter pulmonary valve.
"We learned that the need for reinterventions in the prior trial was primarily due to stent fracture," she said. To reduce the fracture risk, she and her associates routinely began by placing stainless steel stents in the pulmonary artery, an approach known as "pre-stenting," which makes "the risk of fracture go down significantly," she said. Investigators in the new study used pre-stents in 76% of the cases, compared with 35% in the first study. "Our practice now is to pre-stent almost all patients," Dr. Armstrong said.
The results also showed that high right-ventricular pressure prior to valve placement was the only variable independently associated with subsequent valve dysfunction. "Patients who go into the procedure with a very stenotic conduit are probably at higher risk for transcatheter pulmonary valve dysfunction down the road," she said.
The study was sponsored by Medtronic, which markets the Melody transcatheter pulmonary valve. Dr. Armstrong said that she has received consultant fees and honoraria from Siemens Healthcare and St. Jude Medical, and has received research funding from Medtronic and Edwards Lifesciences.
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