Implantable defibrillators lower risk of
death in older heart patients
21 January 2009
Implantable cardioverter defibrillators (ICDs) can improve survival
in patients with heart damage — even those in their 70s — according to
research reported in Circulation: Cardiovascular Quality and
Implanted ICDs reduced the risk of dying by 30% in patients younger
than 65 years old, 65 to 74, and 75 and older, said Paul Chan, MD, lead
author of the study and assistant professor at the Mid-America Heart
Institute and the University of Missouri in Kansas City.
Patients who have damaged heart muscle that results in diminished
pumping action — called left ventricular systolic dysfunction — are
candidates for ICDs to prevent death from life-threatening arrhythmias.
The tiny devices are implanted under the skin and connected to the heart
muscle by electrodes. An ICD automatically shocks the heart back into
normal rhythm when the ICD detects life-threatening rhythms.
Previous studies of ICDs have been conducted in patients who are
primarily younger than 75, and who have few complications such as
diabetes, chronic obstructive lung disease or a history of stroke.
This primary prevention study recruited 986 consecutive patients who
had diminished left ventricular function — meaning the pumping chamber
of the heart was functioning at no more than 35% of capacity. Patients
were treated from March 2001 though June 2005 and followed through March
Researchers compared outcomes of 500 patients who received ICDs to
those who didn't receive the devices. The median age of patients was 67.
This was about seven years older than participants in an earlier study
that investigated the use of ICDs in patients with heart failure (the
SCD-HeFT trial) and about three years older than participants in a study
that reported on the use of ICDs in patients who had heart attacks (the
Researchers said theirs was one of the first studies to examine
whether the benefits of ICDs from controlled clinical trials apply to
real-world patients. Their study was also the first to examine a
clinically well-characterized primary prevention group with patients of
both ischemic and non-ischemic causes of heart damage with more than
three years of follow-up.
"We sought to determine the effectiveness of ICDs in real-world
patients who are older and have multiple co-existing illnesses," Chan
Overall, 238 deaths occurred — 130 (26.7%) in the non-ICD group and
108 (21.6%) in the ICD group. Of these, 116 were attributed to
arrhythmia — 67 (13.7%) in the non-ICD group and 49 (9.8%) in the ICD
"The ICD reduced all-cause mortality by 30% compared with patients
who didn't receive ICDs," Chan said. "The use of ICDs in general
practice reduced mortality similar to the levels seen in clinical
trials. And, the use of ICDs in older patients and patients with
comorbidities reduced mortality both in relative and absolute terms."
When researchers studied patients age 75 or older, they found that
the level of survival benefit remained intact. But the benefit
diminished when age was combined with multiple disease conditions.
The caveat, Chan said, was that "cost effectiveness estimates for ICD
therapy in this study population depended upon both the degree and the
number of comorbidities." Chan and his colleagues also reported in the
paper cost-effectiveness estimates for the use of ICD therapy by age and
The study was limited because of the relatively few patients in their
80s. "I feel comfortable applying the findings to septuagenarians, but
we continue to have limited data on ICD use among octogenarians," Chan
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