Commenting on the study, A. Pieter Kappetein, MD, Erasmus Medical Center, Rotterdam, the
Netherlands, said that the Vancouver group’s findings
put TAVR in “a little bit of a different light” than the
one shone on it only 7 weeks previously when the
PARTNER 2A results were presented. The new data
and reinforce the need to do more trials on different
patient subsets, using newer valve technologies. He
noted, however, that not all surgical valve designs
have shown great durability either, so the findings
are somewhat expected and not terribly surprising.
THVs are complex designs with multiple parts, all of
which have to maintain integrity under constant use.
(And crushing the whole thing into a catheter for
delivery probably doesn’t help either.)
“Lifetime durability cannot be reached with
any biological heart valve, especially in young age
groups,” wrote Hans-Reiner Figulla, MD, and colleagues, in a recent review and clinical update on
transcatheter valve technologies.5 “Until now there
is no evidence that TAVI has less durability when
compared with surgical tissue valves,” they added.
This European Heart Journal review was published
shortly before the Dvir data were presented at EuroPCR, but the second author on the review was John
G. Webb, MD, who was also the senior author on the
Dvir study. The authors concluded: “In the future, TAVI
might replace SAVR with biological valves completely.”
Dr. Figulla is from the Friedrich Schiller Universitat Jena, in Jena, Germany, and Dr. Webb from
the University of British Columbia in Vancouver,
Canada. Dr. Webb and his team were the first to
perform a retrograde transfemoral TAVR and the
first transapical TAVR, both in 2005.
Mitral Valve Plays Second Fiddle
If TAVR is the prom king, then transcatheter mitral
valve intervention is his good-looking best friend. In
terms of prevalence and clinical significance mitral regurgitation (MR) is behind aortic stenosis, but only just.
In pooled data from three large, national,
population-based epidemiological studies (CARDIA,
ARIC, and CHS), mitral valve disease reigned as the
most common valvular lesion. At least moderate
MR occurred at a frequency of 1.7%, as adjusted to
the U.S. adult population of 2000, increasing from
0.5% in participants aged 18 to 44 years to 9.3% in
participants aged ≥ 75 years.1 For comparison, the
prevalence of mitral stenosis in the 75 years and
older population was just 0.2%.
Surgery remains the gold standard for the treatment of severe MR, but up to 50% of these patients
have comorbidities that preclude surgical treatment.6
Hence, we have a clear clinical need for a safe and effective transcatheter therapy.
If investment is any indicator of future success,
then the transcatheter mitral field looks set to take off.
In the last 18 months, there has been a wave of mergers and acquisitions activity in the transcatheter mitral
valve arena, with industry heavyweights Edwards
Lifesciences, Medtronic, Boston Scientific, HeartWare,
and Abbott all making strategic investments.
26 CardioSource WorldNews: Interventions
MitraClip Rules in the Locker Room
Today, transcatheter mitral valve intervention is
mainly limited to repair with the MitraClip, which
was carefully studied in the EVEREST and EVEREST II trials. Encouragingly, registries including
high-risk and inoperable patients report good safety
and functional improvement in patients with both
primary and secondary MR.
But for all of the success seen with the MitraClip,
the field remains wide open. In the US, the device is
only approved for severely symptomatic patients with
primary MR who are at high or prohibitive surgical
risk. It remains unclear how well the MitraClip performs in patients with functional MR, and whether it
improves survival. And the procedure clearly does not
eradicate the MR, but does improve it.
A number of alternative or complimentary
devices are under investigation (TABLE), including
some, such as the Mitralign, that are designed to
treat functional MR. The Mitralign system directly
tightens the annulus and appears to work in both
the mitral and tricuspid valves.
Repair or Replace, Percutaneously Speaking?
“I think we are probably going to end up with the
same kind of combined strategy. On the one hand,
we’ll probably have percutaneous mitral valve repair,
not in isolation but in combination: we have the
MitraClip and we also have direct annuloplasty with
the Cardioband. The two of them will work very
nicely together and this will be applied in patients
probably at a somewhat earlier stage of the disease,
in those with less advanced anatomic destruction.”
On the other side of the spectrum, patients with very
advanced lesions will more likely get a tr anscatheter
valve replacement procedure, he said.
Dr. Vahanian presented promising 1-year data at
the CRT meeting on the Cardioband (Valtech) device
he mentioned; it’s an adjustable direct annuloplasty
device available for patients with MR and heart failure.
In Sept. 2015, HeartWare agreed to purchase Israel’s
Valtech Cardio for a reported $929 million.
In an interview with CSWN:Interventions executive
editor, Rick McGuire, Robert Bonow, MD, director
of the Center for Cardiovascular Innovation at the
Northwestern University Feinberg School Medicine in
Chicago, was asked to speculate how quickly transcatheter mitral valve intervention might come of age
and start to replace surgical options. He put that event
more than 5 years in the future, but said that it is
likely the treatment of mitral valve disease will one day
involve “more and more catheters.”
Said Dr. Bonow: “The mitral field is much more complicated [than the aortic] because it’s a more complicated
set of lesions that can cause mitral regurgitation, not one
size fits all. The only device we have right now [MitraClip] is evolving. We have lots of highly experienced
centers, but it’s the first generation of the device. Now
we’re starting to see newer devices for both repair and
replacement, but those are very early on.”
One interesting question unanswered in the mitral
arena is whether transcatheter repair will be better,
worse, or equal to transcatheter replacement. Surgically speaking, repair is recommended when possible
to avoid lifelong anticoagulation, prosthesis issues, and
operative risk. But will the same hold true for percutaneous mitral valve interventions?
This issue was discussed by Alec Vahanian, MD,
Bichat Hospital, Paris, France, at the recent CRT 2016
meeting in Washington, DC. In an interview with
CSWN:Interventions, he said that it’s really too early
to draw any firm conclusions as to which will be the
dominant procedure. When it comes to comparing
data, it isn’t even a fair fight: in this corner, mitral
Tricuspid Valve: Wanna-be or Budding Big
repair with the MitraClip device on more than 30,000
Man on Campus?
patients worldwide, with numerous patients available
The tricuspid valve (TV), sometimes referred to as
for at least 5 years of follow-up versus less than 100
“the forgotten valve,” could be the sleeper hit of the
patients treated with transcatheter mitral replacement
transcatheter valve world. Moderate or severe tricuspid
and its limited follow-up.
regurgitation (TR) is estimated to affect 1.6 million
What we can do, said Dr. Vahanian, is draw some
people in the U.S. but fewer than 0.5% of them will
lessons from the surgical field, where mitral valve
undergo surgical tricuspid repair or replacement.
repair and replacement have been shown to be “someFunctional TR is more common and more imporwhat complimentary methods.” However, some lessons
tant than most people think. For example, in TAVR
learned may go in the other direction with the “new
patients, about a quarter have moderate-to-severe TR
kid” perhaps offering insights that the surgical masters
persisting after their aortic intervention, according to
might learn from: that’s because the transcatheter data
Dr. Webb (whom we met earlier).
will be based, as Dr. Vahanian put it, on sound
TABLE Approved Transcatheter Mitral Valve Repair Technologies
scientific evidence,
unlike in the surgical
Device Name (Company)
Therapy Type
Status
field where there are
MitraClip (Abbott Vascular)
Edge-to-edge repair
CE marked and FDA approved
virtually no prospective
NeoChord
(NeoChord
DS1000)
Chordal
repair
CE
marked
randomized data on
this issue and where
CARILLON (Cardiac Dimensions)
Indirect annuloplasty
CE marked
concern persists that
Mitralign Bident (Mitralign)
Direct annuloplasty
CE marked
too many patients are
Cardioband (Valtech)
Direct annuloplasty
CE marked
being sent for replacement instead of repair.
Adapted (and updated) from Testa L, et al.6
July/August 2016