Angioplasty and Stenting
from the Wrist Safe and Effective: The RIVAL Trial
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April
8, 2011 --
The first large-scale trial comparing angioplasty performed via
the wrist (transradial) with the procedure
done from the leg (femoral)
was presented at this week's annual
meeting
of the American College of Cardiology. Dubbed "RIVAL" (RadIal
Vs. FemorAL Access for Coronary Intervention Study) the
trial enrolled 7,021 patients from 158 hospitals in 32
countries. These were patients with Acute Coronary Syndrome
(ACS) who were experiencing unstable angina or a heart
attack (either NSTEMI or STEMI) -- and who were going to be
treated with
angioplasty
and/or stents
The question for the RIVAL study: Is
radial access superior to femoral?
Background
Although radial is used more
than half the time in many countries around the world,
only 5-7% of cases in the United States are done
this way, even though cardiologists who perform diagnostic
catheterizations, angioplasty and stenting from the radial approach
report much
lower bleeding complications, much increased patient comfort and
quicker
recovery.
So the results of RIVAL were much anticipated
by the U.S. cardiologists gathered this week in New Orleans. In
fact,
Dr. Ralph Brindis, president of the American College of Cardiology,
stated before the meeting that the adoption of transradial access
may be "at
a tipping point".
Results
The RIVAL study looked at patient outcomes 30
days after the procedure; the primary endpoint to
be measured was a composite of
death, heart
attack,
stroke or
non-CABG
major
bleeding.
Although a number of previous studies have shown that the transradial
approach virtually eliminates access-site bleeding complications,
the results
of
RIVAL did not prove superiority of either the wrist or leg approach.
There was no statistically significant difference in the
composite:
about 4 out of 100 patients suffered one
or more
events, whether
they were in the radial or femoral group (3.7% in the radial
group and 4.0% in the femoral).
Although there was no "winner", in fact both approaches
were winners, in that the events were low in frequency. Furthermore
the wrist approach has now been shown to be as safe and effective
as the much more widely-utilized leg/groin access site, countering
any remaining arguments against its widespread use.
Increased Vascular Complications with Femoral Approach
However,
there was a big difference in major vascular complications, an "additional
secondary endpoint" defined
as: pseudoaneurysms needing closure, large hematoma (as judged by
investigator),
arteriovenous
fistula,
or an ischemic limb needing
surgery. And, while these were not part of the primary endpoint composite,
such complications are not small problems; they affect the
patient, length of stay and
recovery,
and
they most definitely
increase
hospitalization
costs. In the transradial group, major vascular complications were
1.4%, while in the femoral they were more than 2 1/2 times greater
at 3.7%. A major vascular complication needing surgical repair can
be a very expensive complication, and a debilitating one for the
patient.
Two of the most posted to topics on Angioplasty.Org's
Patient Forum have to do with complications from femoral
catheter-based procedures and femoral
vascular closure devices. Over 1,300 posts
delineate the various types of problems encountered in the real world
by patients: from minor bruising and soreness to vascular injury
requiring surgery or persistent nerve trauma which permanently has
limited running, bicycling, even walking -- even a few stories of
retroperitoneal hemorrhages, not discovered in-hospital (as they
often are not), which resulted in death. To be sure, these femoral
complications are still small in percentage, but can be devastating
to patients.
Advantage for Transradial Seen in STEMI Patients
Other
differences were also seen, for example, in patients who were treated
for the
most
serious
type
of
heart attack:
an ST Elevated Myocardial Infarction (STEMI). Here the primary endpoint
showed a lower
event rate for the radial technique vs. the femoral
(3.1% vs 5.2%). One reason may be that STEMI patients are given
much higher doses of antithrombotic drugs during the procedure to
keep their blood from clotting,
thus raising the risk for bleeding complications at the
access site. Radial showed a clear advantage for STEMI patients.
Low Event Rates and Selection of Operators
May Have Affected Results
As has been the case in several recent interventional cardiology trials,
unexpectedly low event rates overall may have muddled the comparisons.
Even though the investigators increased the sample size from 4,000
to 7,000 in 2009, when it became clear that event rates were lower
than originally planned for, they wrote:
"RIVAL was underpowered to conclusively rule out moderate
but important differences in the primary outcome. On the basis
of the reported event rate of 4%, a sample of size of 17,000
patients would be needed to have 80% power to detect a 20% relative
risk reduction in the primary outcome." |
Another concern
expressed by some was that the bar for radial operators was
too low
-- those
chosen
to
take
part
in RIVAL had to have done at least 50 radial procedures in
the previous year, considered by most "radialists" to be
a very low volume. Most experienced radial operators feel that just
to get past the initial learning curve takes about 100 cases. A
cardiologist who practices "Radial
First" uses
the radial approach as the default for all cases and therefore
would normally have a much higher annual volume. As expected, the
study
showed better outcomes at centers with high radial
case
volume.
Perhaps,
if only
the most
experienced
radial
operators
were measured against the most experienced femoral operators, the
outcomes might have favored radial even more.
Even though the final conclusion of the RIVAL study
did not show superiority of one approach,
the RIVAL investigators, led by Dr. Sanjit Jolly of McMaster University's
Population
Health Research Institute in Hamilton, Ontario, concluded
that:
Dr. Sanjit
Jolly |
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"Radial and
femoral approaches are both safe and effective for PCI....
In patients with ACS undergoing
coronary angiography, radial access did not reduce the
primary outcome of death, myocardial infarction, stroke,
or non-CABG-related
major bleeding compared with femoral access.
"However, radial
access significantly reduced vascular access complications
compared with femoral access, with similar PCI success
rates, and was more commonly preferred by patients for
subsequent
procedures." |
So the question remains whether the RIVAL
trial results will push the adoption of transradial access past
Dr. Brindis' "tipping point." There has been a groundswell
of interest in the transradial approach over the past couple of years
and every
major interventional meeting now hosts a transradial training component.
Other organizations, companies and most recently, the Society for Cardiovascular
Angiography and Interventions (SCAI), also have started scheduling
one or two day training courses in radial access. SCAI, in fact, issued
a statement on the outcomes of the RIVAL Trial earlier
this week. Still, moving the entire subspecialty of interventional
cardiology from 5% to a "tipping point" will take commitment
on the part of cardiologists who want to learn this technique, and
will most
likely be driven by patient preference.
The RIVAL study was published
online in The Lancet,
simultaneously with its presentation at the ACC meeting.
About The Radial Access Center on Angioplasty.Org
To assist in educating the professional and patient population in the U.S.
about the this technique, Angioplasty.Org created the "Radial
Access Center for Transradial Approach" in 2007, a special
section devoted to information and news about the transradial technique,
for both patients and physicians. The Radial Center features interviews with
leading practitioners of the radial technique, such as Drs. Jeffrey Popma,
Sunil Rao, Mauricio Cohen, John Coppola, Shigeru Saito and Jennifer Tremmel.
For interventional cardiologists and cath lab staff,
Angioplasty.Org also maintains a
listing of upcoming training courses in the transradial approach.
For patients, there is a unique "Radial
Hospital Locator" that lists U.S. centers
practicing radial angiography. As Dr. Howard Cohen of Lenox
Hill Hospital
in New York says of the wrist technique, "Patients really
prefer it. 95% of people who've had it both ways would say
'I'm coming back to you, Dr. Cohen because I like this transradial
a lot better than the other way!'
Reported by Burt Cohen, April 8, 2011
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