Devices for PFO Closure Range from Stent to Suture 
      
Key Points:
Concerns over clinical trial design present some obstacles.

By TCT Daily Staff

Several novel devices and therapies designed to close a patent foramen ovale are on the brink of entering clinical trials.

The Coherex FlatStent nitinol implant is a novel device designed for deployment in the tunnel of the PFO; it stretches the opening to appose the septal walls. The stent design consists of an accordion body and flexible atrial anchors. One model, the Coherex FlatStent Enhanced Foam, contains interwoven polyurethane foam targeted to the PFO tunnel and the right atrial opening. The enhanced foam, which has been shown in porcine models to enhance tissue growth, has been used in humans.

"The Coherex FlatStent is a low mass, tunnel-specific implant, and patent foramen ovale closure using the Coherex FlatStent is safe," Brian Whisenant, MD, an interventional cardiologist at the Utah Heart Clinic in Salt Lake City, said in his presentation. "We welcome engaging with the national and international community of neurology and cardiology to try and understand this complicated space and address this unmet clinical scenario."

The CoAptus Radio Frequency Ablation Patent Foramen Ovale Sealing System uses radiofrequency ablation to seal the walls of the septum. With this system, early methods using suction to hold the walls of the septum together and a radiofrequency electrode in place during ablation were unsuccessful outside of animal models.

The current system uses mechanical coaptation to hold the walls of the septum together during ablation, resulting in better seals.

"Current mechanical devices that are placed in the patent foramen ovale force the heart to conform to the shape of the device," said Thomas K. Jones, MD, professor of pediatrics and medicine at the University of Washington. "The goal of this closure system is to have a system that is able to conform to the variable anatomy of the human patent foramen ovale and leave nothing behind," Jones said.

Another approach being explored is a suture-based therapy by Sutura. An advantage of the suture-based approach is the amount of data suggesting relative safety with polypropylene suture material, which helps avoid potential tissue inflammation associated with energy-based devices.

"The way the suture is placed actually provides a double-curve and creates a valve-like mechanism by folding the septum primum when it is sutured," said Carlos E. Ruiz, MD, PhD, director of cardiac intervention at Lennox Hill Heart and Vascular Institute of New York. "We believe this may have a better sealing effect than one single suture."

Although a first-in-man study using the suture-based device has been completed, difficulties in defining risk and benefit, ethical considerations and validity concerns have made designing a clinical trial for the system difficult, according to Ruiz.

Disclosures:

Dr. Whisenant is a founder of and has ownership in Coherex Medical.
Dr. Jones reports receiving consulting fees from AGA Medical Corporation and W.L. Gore & Associates Inc. Dr. Jones also reports receiving consulting fees and having an equity interest in CoAptus Medical Corp.
Dr. Ruiz reports receiving consulting fees from Sutura and CoAptus Medical Corp. Dr. Ruiz also is a proctor for NMT and AGA Medical Corporation.