Medtronic plc has received the first FDA approval for a transcatheter pulmonary valve to treat patients whose bioprosthetic pulmonary heart valves have failed. For these congenital heart disease patients, many of whom undergo repeat open heart surgeries as children and into adulthood, this validates the use of the Melody Transcatheter Pulmonary Valve (TPV) to avoid additional surgical procedures.

BEYOND OFF-LABEL USE

The Melody TPV has long been used off-label in this indication, but a retrospective study underlying the approval found that it's effective even in pediatric and adult patients with a smaller valve. It is an artificial heart valve made from the jugular vein valve of a cow that is sewn into a small metal frame. It's inserted via a catheter threaded through a small incision typically in the groin and placed while the heart is beating.

It was FDA approved in 2015 for congenital heart disease patients with a dysfunctional right ventricular outflow tract conduit, which is an animal- or cadaver-based graft with a valve inside that connects the heart to the lungs. Prior to that it was available under a Humanitarian Device Exemption from the FDA that dates back to 2010. The Melody TPV won a CE mark in 2006 to treat patients with failing pulmonary valve conduits.

"All bioprosthetic valves, catheter-placed or surgically placed, will likely undergo some deterioration, although they do provide a fairly long-term solution," Mayo Clinic pediatric cardiologist Allison Cabalka, who was the principal investigator on a retrospective study of bioprosthetic valve replacement, told Medical Device Daily.

"The patient would have had a surgically placed tissue valve and when that valve undergoes deterioration, which can be in a few years to 10 years after the valve is placed, they have the option of transcatheter placement," she said.

BUYING TIME WITH A TPV

During a bioprosthetic valve replacement procedure, the Melody TPV is placed within the existing, older bioprosthetic valve, pushing it to the side rather than attempting to retrieve it. The nonfunctioning bioprosthetic valve is left in place and provides a "fairly nice framework to support the Melody valve," said Cabalka.

The Melody TPV has been used in more than 10,500 patients worldwide. Patients in the original IDE study for Melody TPV are being followed for 10 years, ending in January 2020. The initial results at five years showed that 91.7 percent of patients were free from conduit reoperation.

In the new indication, an estimated 5 percent of congenital heart disease patients – whose bioprosthetic pulmonary heart valves have failed – are eligible for the Melody TPV or other transcatheter options.

Cabalka headed a 10-center retrospective study of Melody TPV use in bioprosthetic valves, which she said found that it "works very well in both pediatric and adult valves." She noted that the procedure requires only a one-night hospital stay with the obviation of open heart surgery.

"The idea of catheter-based surgery is to extend the life of the valve; it is very important to avoid complications from repeated open heart surgery," she said. "If we didn't have a catheter-based option to treat bioprosthetic valve failure, then they would have to undergo surgery. They will typically suffer ventricular dysfunction in the right ventricle, the tricuspid valve may also fail."

Continued Cabalka, "Waiting, in terms of preserving overall heart function for years, is not a good option. Functionally speaking, the only other option is open heart surgery."

GOING SMALLER AND BIGGER

Even though off-label use was common, she expects that the FDA approval could help bolster use in smaller patients that were previously a particular concern. "I suspect that there may be more use of the Melody valve or other transcatheter solutions, especially in younger patients with a smaller valve or adult patients with a smaller valve," she said.

"We have seen in our analysis that valve function is very good. Before, there may have been concerns that it would be limiting in terms of hemodynamics," concluded Cabalka.

She added that the use of Melody TPV could also prove useful as a repeat procedure, depending on the nature of the valve the system is implanted into. That could provide these patients more options to avoid open heart surgery and associated complications.

For small children who see more stenosis, or narrowing, as they become adults, Cabalka envisions that they could undergo open heart surgery – thereby laying the foundation for transcatheter procedures for the rest of their lives.

Beyond the Melody TPV in congenital heart valve development, Dublin-based Medtronic is also in the midst of a pivotal trial for the Harmony TPV. It is an investigational transcatheter pulmonary valve designed for the roughly 80 percent of patients whose initial procedure is insufficient to open up their right ventricular outflow tract (RVOT). The expectation is that the Harmony TPV will be an alternative to open heart surgery for these pediatric and adult patients.