Implantation of the Melody transcatheter pulmonary valve (Medtronic, Minneapolis) for right ventricular outflow tract conduit dysfunction can be performed by experienced operators at multiple centers, appears safe, and has encouraging acute and short-term outcomes, according to a study in the Oct. 27 issue of the Journal of the American College of Cardiology.
An FDA advisory panel unanimously recommended FDA approval of the Melody valve on July 22. If approved, the device would become the first transcatheter heart valve of any kind to receive FDA approval for use in the U.S. The device is currently under FDA review for a humanitarian device exemption.
The study was designed to evaluate the safety, procedural success and short-term effectiveness of the Melody valve in patients with dysfunctional right ventricular outflow tract conduits. Prior to this study, there had been no prospective, multicenter trials evaluating this technology.
Between January 2007 and September 2007, Evan M. Zahn, MD, from the division of cardiology at Miami Children's Hospital in Miami, Fla., and colleagues enrolled 34 patients to undergo catheterization for intended Melody valve implantation at three centers. Mean age was 19.4 years. Also, initial conduit Doppler mean gradient was 28.8 mm Hg, and 94 percent of patients had moderate or severe pulmonary regurgitation.
The researchers reported that implantation was successful in 29 of 30 attempts and not attempted in four patients. Procedural complications included conduit rupture requiring urgent surgery and device removal (one patient), wide-complex tachycardia (one patient) and distal pulmonary artery guidewire perforation (one patient).
Peak systolic conduit gradient fell acutely from 37.2 mm Hg to 17.3 mm Hg, and no patient had more than mild pulmonary regurgitation, according to the authors. There were no deaths or further device explants.
Also, the average hospital stay of just more than one day in this study compares favorably with both surgical conduit replacement and bare-metal stenting.
At six-month follow-up, Zahn and colleagues wrote that the conduit Doppler mean gradient was 22.4 mm Hg, and pulmonary regurgitation fraction by MRI was “significantly improved (3.3 vs. 27.6 percent). Stent fracture occurred in eight of 29 implants; three of these were treated with a second Melody valve for recurrent stenosis later in follow up.
The authors noted that further study would be warranted in various areas. “It will also be important to determine the role of pre-dilation and/or pre-stenting in preventing recurrent right ventricular outflow tract obstruction.” They added that further examination of the physiologic mechanisms underlying changes in exercise performance and symptomatic improvement also is “warranted.”
While Zahn et al touted the success of the device in this trial, they concluded that longer follow up and a larger patient experience are needed to determine the ultimate role of this therapy in the treatment of conduit dysfunction.