Arundhati Parmar

Edwards Lifesciences announced Tuesday that the company is pausing enrollment in a trial studying its transcatheter mitral valve replacement therapy.

The trial, called FORTIS, has produced valve thrombosis in patients that Edwards believes warrants further investigation. The news release said more than 20 patients have been treated with TMVR therapy, but didn't specify how many patients showed valve thrombosis, a serious but rare complication of valve replacements. Valve thrombosis occurs when a blood clot - a thrombus - is formed near or is attached to the prosthetic heart valve. This can block blood flow and the functioning of the artificial valve, according to the NYU Langone Medical Center.  

Edwards' product uses bovine pericardial tissue and features a cloth-covered self-expanding frame designed to minimize paravalvular leak, one of the side effects of transcatheter heart valve procedures. This product is introduced in the heart through a transapical approach, whereby the valve is delivered via a catheter through the apex of the heart to allow direct surgical access to the mitral valve complex, according to a news release.

TMVR is aimed at patients who suffer from mitral valve disease and are considered to be unfit for risky, open-heart surgery. There are two kinds of mitral valve disease, according to the Mayo Clinic. Mitral valve regurugitation occues when the mitral valve leaflets don't close properly  causing blood to leak back into the left atrium of the heart. Mitral valve stenosis is the hardening of the valves such that they may fuse together leading to reduced blood flow from the left atrium to the left ventricle.

In March 2014, Edwards, announced it had performed the first three human implants of the new device in Europe. Other startups and establlished companies are also endeavoring to build the TMVR space. 

Minnesota startup Tendyne Holdings performed first-in-human implants using its Tendyne Bioprosthetic Mitral Valve as part of a global feasibility trial in the Minneapolis Heart Institute last month. The product treats mitral valve regurgitation and iscomprisedofa "tri-leafletporcinepericardialvalvesewnontoa nitinolframethatistetheredtoapexoftheheart," according to a news release.

Medtronic disclosed in an October investor meeting at the Transcatheter Cardiovascular Therapeutics conference that it has completed animal studies of a TMVR product and is continuing chronic studies. That system is made up of a self-expanding nitinol and a cylindrical, tri-leaflet pericardial heart valve that has minimum extension into the left ventricle of the heart and preserves the native mitral heart apparatus. 

A Canadian company is also testing its version of a TMVR product. Neovasc, a public company based in Vancouver, announced in December that it has implanted its product in a patient as part of its TIARA-I trial being conducted in Canada, Europe and the United States. 

Two other companies that are testing its mitral valve products in humans are Twelve and CardiAQ, according to Glenn Novarro, an analyst with RBC Capital Markets. In a research note published Tuesday, Novarro speculated that if Edwards is forced to halt its TMVR program, it could acquire other companies also testing their respective products.

Arundhati Parmar is senior editor at MD+DI. Reach her at [email protected] and on Twitter @aparmarbb