Medtronic Cardiac Valve Found Effective as CHD Bridge Treatment

Pediatric interventional cardiologists may proceed with more confidence with bridge treatments for patients with congenital heart disease, based on a clinical trial. The post-approval analysis of a transcatheter valve gave it high marks in real-world practice.

“It confirmed what was found in the IDE (investigational device exemption study) and supports that the procedural success is high, that it is a safe valve and at least through the first year the valve function is excellent,” lead researcher Aimee K. Armstrong, M.D., associate director of the University of Michigan C.S. Mott Children’s Hospital Cardiac Catheterization Laboratories told Cardiovascular Business. “It supports what we found in the trial done more than five years ago.”

The researchers evaluated the safety and effectiveness of the Melody Transcatheter Pulmonary Valve (Medtronic Inc.), which had been approved by the U.S. Food and Drug Administration (FDA) in 2010 under a Humanitarian Device Exemption. The device was developed as a technology that delays the time to surgery in patients who typically undergo several operations in their lifetime. As part of the device approval, the FDA required a multicenter, short-term hemodynamic effectiveness study.

Ten centers in the United States that had not been part of the IDE enrolled 120 patients with stenotic or regurgitant conduits for implantation. Unlike the IDE, the inclusion criteria did not have a weight or age restriction.

The primary endpoint was acceptable hemodynamic function at six months after implant. Secondary endpoints were procedural success, freedom from serious adverse events and freedom from valve dysfunction.

Implants were attempted in 101 patients, and 99 patients had implants of more of 24 hours for a procedural success rate of 98 percent. The rate of acceptable hemodynamic function was 96.7 percent with evaluable echocardiographic data and 87.9 percent overall, which met the primary endpoint.

“This was significantly better than the performance goal of 75 percent established in the IDE,” Armstrong said, adding that results were maintained through one year.

The rate of freedom from valve dysfunction was 97 percent at one year, higher than what had been achieved in the IDE study. “We had fewer fractures and less need for reintervention because of fractures,” she said.

In the IDE study, interventional cardiologists treating the first 35 patients were not allowed to do other procedures such as stenting or angioplasties. “What we found is that some of these valves can develop a fracture,” Armstrong told Cardiovascular Business. “It typically does not cause leakage but it can lead to some narrowing. There were more of these fractures in the IDE study because they hadn’t done pre-stenting,” which is now done in most cases.

At baseline, 85 percent of patients had severe or moderate pulmonary regurgitation and no patients had that level of severity at discharge. At one year, there was a trend toward an increase in mild pulmonary regurgitation, from 6.4 percent at six months to 12.2 percent at one year. “Mild regurgitation in the scheme of heart disease is pretty trivial,” Armstrong said. It doesn’t compromise quality of life, she added.

The procedural adverse events occurred in 16 patients at six months and eight patients at one year.

When asked about risk factors that might predispose patients to valve failure as well as the 3 percent rate of endocarditis, Armstrong responded that patients undergoing the procedure who are very stenotic are at risk of valve dysfunction.

“The (endocarditis rate) requires further follow-up,” she replied. The rate was similar to that in the IDE trial and in patients who have not received new valves. “These patients are at risk for endocarditis.”