A comparison of techniques
for repairing potentially lethal abdominal aortic aneurysms
(AAA) casts serious doubt on most provinces' policies
on dealing with AAA. Abdominal aneurysms kill more Canadians
than ovarian cancer, brain cancer, or AIDS. The mortality
rate could be reduced by two-thirds in the first month
by using a new, less invasive technique rather than the
traditional open surgery (OSR) approach, according to
a study published in the August 31 issue of The Lancet.
The study recruited 1,082 AAA patients
aged 60 or older, of whom over 90% were men, from 41
different hospitals. Mean aneurysm diameter was a menacing
6.5 cm, a size that generally implies death within 12
months. Subjects were randomized into either OSR or
endovascular aneurysm repair (EVAR), in which a device
called an endograft is delivered to the site of the
aneurysm by a catheter system inserted via the artery
in the groin.
Thirty-day mortality in the EVAR
group was 1.7%, compared to 4.7% in the OSR group. However,
9.8% of EVAR patients required secondary interventions
compared to 5.8% of OSR patients. But then, if something
goes wrong during open abdominal surgery, a second try
may not be an option - since the patient is quite likely
to be beyond help.
Lead researcher Dr Roger Greenhalgh
of London's Imperial College believes, however, that
30 days' followup is not enough to compare two procedures.
His team will release longer-term mortality rates next
year. The graft implanted by open surgery can generally
be trusted to last over 20 years, long enough to see
out the lifespan of most AAA patients. There is, as
yet, no way of knowing if EVAR can match that, especially
since the technique has been refined considerably since
its inception in 1991. Longterm results from early efforts
might mislead us about the future prospects of today's
EVAR patients.The authors argue that "these early results
with EVAR, applied to large aneurysms in patients judged
fit for open repair, provide justification for continued
use of this technique in controlled or trial settings."
However, they acknowledge, "the early promise of endovascular
repair cannot be guaranteed and might not endure in
the longterm. The 30-day mortality results are a licence
to continue scientific evaluation of EVAR, but not to
change clinical practice."
Currently, the overwhelming majority
of Canadians opt for OSR for aneurysms. This is partially
due to a 2002 report by the Ontario Ministry of Health
that found that "no definitive conclusion regarding
the longterm effectiveness or cost-effectiveness of
EVAR can be drawn." It also reported higher cost for
EVAR than for OSR because of the pricey devices. Nonetheless,
the latest research in The Lancet suggests that
EVAR deserves a better chance to prove itself.
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