Arundhati Parmar

Transcatheter aortic valve replacement therapies have been gaining ground over the past several years as Edwards Lifesciences and Medtronic have introduced competing TAVR valves in the U.S. even as Europe boasts more players and approved products.

As this therapy gathers clinical evidence, a market forecast is available. 

In a research note on Thursday, Glenn Novarro, an analyst with RBC Capital Markets, wrote that once more lower risk people with aortic stenosis are brought into the fold of TAVR, the global market will be worth $5.5 billion by 2020.

So why is TAVR gaining ground? Replacing diseased heart valves typically require surgeons to break and rib and perform invasive, open heart surgery. But many patients are too sick to endure the physical trauma of open heart surgery and some are plain inoperable. 

And that latter group of patients have been where TAVR made its mark first. The procedure uses a catheter to snake an artificial heart valve through the femoral artery in the leg -- called the transfemoral approach -- or directly through the apex of the heart -- called the transapical approach.  

But as the therapy has been proving itself, and as companies are introducing advanced iterations of initial devices, doctors and regulators are feeling more comfortable in allowing the devices to be used for patients who don't have high risk to open heart surgery. For TAVR, the two biggest complications that device makers and doctors have to manage is paravalvular leak that can lead to stroke and the need to implant pacemakers.

Data presented at the EuroPCR conference in Paris in May shows that the first randomized clinical trial to pit TAVR against surgical procedure in lower-risk patients found that the rates of stroke were lower in the minimally invasive approach when compared with open heart surgery and surgical valve replacement.

Two years after the procedure, rate of stroke was 3.6% among patients treated with TAVR compared with 5.4% treated surgically. Death from any cause, stroke or myocardial infarction was low in both groups with TAVR edging out slightly (15.8%) compared with 18.8% among those treated using surgery.

The study called NOTION was funded by the Danish Heart Foundation and used Medtronic's CoreValve transcatheter system and enrolled patients between 2009 and 2013.

"With low rates of mortality and stroke, the two year outcomes from NOTION show promise that the CoreValve System may be a viable treatment option for a broader patient population," according to a Medtronic spokeswoman.

Novarro of RBC Capital Markets agrees with this idea of using the therapy for people other than just high risk patients. In his note, he wrote that TAVR will "creep into low-risk patients" over the next few years, "similar to what has occurred with intermediate-risk patients."

He believes Edwards, which has led the category, will benefit most from this expansion, noting, "substantial portion of the intermediate-risk market opportunity remains untapped, which provides a long-term runway for Sapien sales" referring to the family of valves that Edwards has developed.

While Medtronic and Edwards duke it out in the U.S., startups are not standing by idly. An Irvine, CA company, with roots in Germany, is developing a new TAVR valve that its CEO believes will demonstrate a winning combination that no other valve has yet achieved. JenaValve Technology is aiming for a valve that will have both low paravalvular leakage and low pacemaker implantation rates believe CEO Victoria Carr-Brendel. 

Meanwhile, Novarro declared that issues of TAVR valve durability, an issue that came up at the EuroPCR meeting in Paris, are overblown and cardiologists don't believe that them to hurt adoption of the therapy. 

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