The Beat Goes On
It used to be a two-horse race, but the international TAVR market is heating
up and filling up with a host of new contenders.
Christopher Delporte • Editorial Director
You say puh-tay-toe; I say puh-tah-toe. TAVR or TAVI? Give or take a consonant, they’re the same thing. Transcatheter aortic valve replacement (or implantation) is a minimally
invasive surgical procedure that replaces the aortic valve of the
heart through the blood vessels as opposed to valve replacement
via traditional open-heart surgery. The market has been dominated by two companies, with others hustling to vie for position.
As the technology grows in acceptance (clinically as well as from
regulatory and reimbursement perspectives), cardiovascular firms
are working on newer versions and indications for the tiny, intricate devices. No matter how you spell it, companies are reading
large market opportunity.
The Clinical Case
The aortic valve is located between the pumping chamber on the
left side of the heart and the aorta, which is a major artery. The
aorta carries oxygen-rich blood from the heart to the rest of the
body. The valve should be closed while the heart is filling with
blood. When the heart chamber squeezes to push blood into the
aorta, the valve should open fully to allow blood flow.
Sometimes, particularly as we age, aortic stenosis—a narrowing
of the aortic valve—can occur. This leads to increased stress and
pressure on the heart muscle, which initially can result in chest discomfort or pain, shortness of breath, leg swelling, fatigue or fainting. Left untreated, the heart muscle can weaken over time resulting in worsening of symptoms and death. The most common cause
of aortic stenosis is degenerative—age-related calcium deposits.
Aortic stenosis is the third most prevalent form of cardiovascular disease in the Western world after hypertension and coronary
artery disease. Considered a potentially life-threatening condition,
the aortic heart valve becomes calcified and does not open properly. Roughly 25 percent of people 65 and older have aortic valve
thickening and 3 percent age 75 and older have severe stenosis.
Somewhat similar to a stent placed in an artery, the replace-
ment aortic valve is delivered via catheter through several access
methods. With TAVR, a fully collapsible (compressed down to
the width of a pencil) replacement is moved to the natural valve
site through a catheter primarily through one of two approaches:
entering through the vein in the groin (called a transfemoral ap-
proach) or from between two ribs through the wall of the heart
(called a transapical approach). Other delivery methods in today’s
practice include subclavian (beneath the collar bone) and direct
aortic (through a minimally invasive surgical incision into the aor-
ta). Placement of the valve happens while the heart is still beating.
Once the new valve is put into place, it is expanded to push the
old valve’s leaflets (the human aortic valve has three leaflets—
delicate flaps—that stop blood flowing back into the left ventricle of the
heart) out of the way and the tissue in the replacement valve takes
over the job of regulating blood flow. The goal also is to prevent aortic
regurgitation, a condition that occurs when the aortic valve doesn’t
close tightly. Aortic valve regurgitation allows some of the blood that
was just pumped out of the left ventricle to leak back into it.
Prior to the introduction of the TAVR option, surgeons had one
primary path available to them—an open-heart procedure with
a sternotomy in which an incision is made, the chest is cracked
apart, the patient is placed on a heart-lung machine (stopping the
heart), and the heart is opened to insert a new valve. Though it
may sound positively barbaric compared to TAVR, it is still the most
common method to replace a diseased valve for patients healthy
enough for the procedure. Other options to treat valve narrowing
include medication for the symptoms (though they don’t stop the
progression of the disease) or balloon aortic valvuloplasty, in which
a balloon is inserted into the aortic valve through a catheter that
temporarily enlarges the valve opening but is temporary.
At present in the United States, TAVR primarily is only indicated for high-risk patients who are considered too frail to undergo open-heart surgery—but experts expect that indication to
broaden as time goes on, additional studies are conducted, new
device iterations are introduced, and safety of the procedure and
technology are proven in the longer-term.
The benefits of the less-invasive procedure are that it’s much
less traumatic for the body and, in most cases, it means a faster
recovery time. A TAVR procedure, experts caution, is not without
risks, but it provides a beneficial treatment alternative to people
who just a few years ago may have had limited treatment options.
The two 800-pound gorillas in the TAVR market at the moment