While defibrillators look pretty nifty on TV shows, most
of us would place them in the "don't try this at home
kids" category without too much thought. However, "at
home" is just the place defibrillation would do the most
good for congestive heart failure (CHF) patients. Thanks
to a study in the January 20 issue of the New England
Journal of Medicine (NEJM), CHF patients in distress
may soon be able to receive defibrillation immediately
from an implantable cardioverter-defibrillator (ICD) —
a pager-size device implanted in the chest. Recommendation
for their use was sparked by the study's results which
show that ICDs can prevent sudden death — they even
fared significantly better than the anti-arrythmic drug
amiodarone.
SHOCK
TO THE HEART
Sudden cardiac events are the leading cause of death
among CHF patients. ICDs help prevent this by detecting
periods of arrythmia and administering an electrical
shock to get the heart back on track. "The goal was
to treat only rapid, sustained ventricular tachycardia
or ventricular fibrillation," explains lead author Dr
Gust H Bardy of the Seattle Institute for Cardiac Research.
The numbers that came out of this
study show that ICDs not only do what they were designed
to do, they do it well. The Sudden Cardiac Death in
Heart Failure Trial (SCD-HeFT) involved 2,521 patients
with CHF. These patients were split evenly into three
treatment groups — conventional therapy plus amiodarone,
conventional therapy plus placebo, or conventional therapy
plus ICD.
There were only 182 deaths in the
ICD group, 23% fewer than in either of the other two
treatment groups, both of which had more than 240 fatalities.
In fact, amiodarone appears to have no survival benefits,
as the mortality rate of the group taking it was just
as high as that of the placebo group during the four-year
study.
CHEAP
LIFE SAVERS
Not only are ICDs effective, but the single-lead ICD
is also relatively inexpensive. So despite the risk
of complications during the implantation procedure,
which occur in about 10% of patients, Dr Bardy suggests
that "the survival benefit associated with simple, shock-only
ICD therapy outweighs any shortcomings of this approach."
The news that ICD treatment improves
survival will be encouraging for the nearly six million
North Americans with CHF. At present, CHF is the most
common diagnosis in hospital patients aged 65 and older,
and half of all newly diagnosed patients die within
five years of diagnosis. The lucky few who are alive,
like US vice president Dick Cheney, owe their good fortune
to ICDs. But as Dr Bardy claims, this latest research
may "raise the standard of care for many patients with
CHF," allowing more of those six million sufferers into
the fortunate fold.
NEJM
Jan 20, 2005;352:225-37
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