LAS VEGAS – that followed 65 patients, a majority of whom were children or teenagers.
After 5 years, 69% of the replacement valve recipients had no valvular hemodynamic dysfunction, compared with a 67% rate among patients enrolled in the original Investigational Device Exemption (IDE) study that led to Food and Drug Administration marketingfor the Melody valve in 2010 under a humanitarian device exemption. (Full approval followed in 2017.)
The 5-year rate of any reintervention, including explants, was 78% in the postapproval study, again similar to the 76% rate reported in the IDE study after a median 4.5 year follow-up (), , said at the Society for Cardiovascular Angiography & Interventions annual scientific sessions.
The new 5-year postapproval study findings “confirm that the hemodynamic effectiveness achieved by real-world providers is equivalent to the historical control established in the IDE study,” concluded Dr. Armstrong, professor of pediatrics at the Ohio State University and director of cardiac catheterization and interventional therapies at Nationwide Children’s Hospital, both in Columbus.
The postapproval study ran at 10 U.S. centers, none of which were among the five U.S. centers that ran the IDE study. Today, the Melody transcatheter pulmonary valve “is very commonly used” at many additional U.S. sites, Dr. Armstrong said in an interview. And the outcomes achieved using the valve likely surpass those seen in the IDE and postapproval studies because of innovations in technique, such as more routine use of “prestenting,” placing a stent in the vascular site where the pulmonary valve conduit will sit to address stenosis at this location and prevent subsequent conduit fracture ().
“In 2010 [when the postapproval study began], we didn’t understand the importance of prestenting the way we do now. In 2010, I did not prestent every patient; now I do,” she said. The results reported by Dr. Armstrong included a 5% cumulative rate of major stent fractures in the Melody devices.
The postapproval study results also documented a concerning 4.5% annualized incidence of endocarditis among pulmonary valve recipients, with a nearly 300% increased rate of endocarditis among patients aged 12 years or younger, compared with older patients. Dr. Armstrong cautioned that this age association may be confounded by other factors, such as a residual pressure gradient in the right ventricular outflow tract of 15 mm Hg or greater. “We are discovering that we need to reduce the pressure gradient as much as we can, to perhaps less than 15 mm Hg, to reduce endocarditis, and that is something we did not know even a year ago. Practice is still evolving.”
The Melody Transcatheter Pulmonary Valve Postapprovalperformed cardiac catheterization for valve placement in 121 patients, and successfully implanted the valve for at least 24 hours in 99 of these patients. Patient age ranged from 5 to 45 years, with a median of 17 years; two-thirds were boys or men. The median age of the patients in the postapproval study was about 2 years younger than in the IDE study. Dr. Armstrong and her associates had previously published the 1-year outcomes from the postapproval study ( ).
The enrolled patients usually needed a new right ventricular outflow tract because of a congenital heart defect, such as tetralogy of Fallot with pulmonary atresia and truncus arteriosus. Patients also included those who underwent a Ross operation. These patients often receive surgical placement of a right ventricular-to-pulmonary artery conduit, which can over time develop stenosis, insufficiency, or both because of calcification, intimal proliferation, and graft degeneration.
Multiple conduit reoperations to restore right ventricular outflow tract function are usually needed over a patient’s lifetime because of conduit degeneration. This makes a transcatheter procedure in a child or adolescent an attractive option because the prosthetic conduit will need replacement relatively quickly, and the transcatheter approach avoids an episode of open-heart surgery.
The Melody system is not the only transcatheter option for treating a leak or stenosis in a right ventricular outflow tract. The Sapien XT Transcatheter Heart Valve, marketed by Edwards, has FDA labelingfor replacement of a dysfunctional right ventricular outflow tract.
Because the Sapien XT system was designed for replacing an aortic valve it’s challenging to place the conduit in the pulmonary valve position, Dr. Armstrong said. Operators find the Sapien 3 valve, a more modern design of the XT model that’s also primarily intended for aortic valve replacement, easier to position than the XT for pulmonary valve replacement, but Sapien 3 does not have FDA labeling for the right ventricular outflow tract indication. The Sapien valves are attractive because they don’t fracture, but Melody is easier to place and operators can reduce the fracture risk by prestenting, she noted.
Overall, the 5-year results from the postapproval study represented success, because 78% of patients who received the Melody device avoided any further interventions during follow-up. “That’s a big deal to a 12, 15, or 18 year old,” said Dr. Armstrong. “A surgically placed valve won’t last long in a teen, so it’s nice to do something noninvasively. It’s great if you can delay surgery for a few years” and avoid having the patient grow out of a surgically placed conduit or developing lots of calcification in the conduit during a growth spurt.
The postapproval study was funded by Medtronic, the company that sells the Melody valve. Dr. Armstrong has received research funding from Medtronic as well as Abbott, Edwards, and Siemens, and she has been a consultant to Abbott.