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Senior Citizen Health & Medicine
Women, Black Men Much Less Likely Than White Men to
Get Life-Saving ICDs
Implantable cardioverter defibrillators shock
heart back into rhythm
 Oct. 2, 2007 - Among senior citizen Medicare
patients, men are two to three times more likely than women to receive
an implantable cardioverter defibrillator designed to shock a heart that
is beating irregularly and put it back in normal rhythm to prevent
sudden cardiac death. And, among people of all ages, fewer than 40
percent of potentially eligible patients hospitalized for heart failure
receive ICDs, and women and black patients are significantly less likely
than white men to receive them. These two studies are reported today in
the Journal of the American Medical Association (JAMA).
Sudden cardiac death is a leading cause of death in
the United States. Overall, the risk of sudden cardiac death increases
with age and is higher in men than in women, although the sex difference
narrows and eventually disappears after age 85 years.
Earlier research has shown the effectiveness of
implantable cardioverter defibrillators (ICDs) in preventing sudden
cardiac death, and Medicare coverage of ICDs has expanded, but many
eligible patients still do not receive them.
Medicare Patient Study
Data for this study came from a five percent
national sample of files from the U.S. Centers for Medicare & Medicaid
Services for the period 1991 through 2005. Lesley H. Curtis, Ph.D., of
Duke University School of Medicine, Durham, N.C., and colleagues
examined the differences between men and women in the receipt of ICDs
for the primary and secondary prevention of sudden cardiac death.
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For People Who Have Survived Sudden Cardiac Arrest
People who have already had Sudden Cardiac Arrest
(SCA) are at high risk of having it again. For these people, research
shows that an implantable cardioverter defibrillator (ICD) reduces the
chances of dying from a second SCA.
An ICD is surgically implanted under the skin. It
continually monitors the heartbeat and delivers a shock to the heart
when it detects a dangerous rhythm. The shocks can be painful, like a
kick in the chest. Medicines can be given to try to reduce how often the
person experiences the irregular heartbeats that trigger the device to
deliver a shock.
See Photo at Top of Page
The illustration shows the location of an
implantable cardioverter defibrillator in the upper chest. The
electrodes are inserted into the heart through a vein.
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More at National Heart, Lung and Blood Institute
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Implantable Cardioverter Defibrillator (American
Heart Association)
An implantable cardioverter defibrillator is used
in patients at risk for recurrent, sustained ventricular tachycardia or
fibrillation.
The device is connected to leads positioned inside
the heart or on its surface. These leads are used to deliver electrical
shocks, sense the cardiac rhythm and sometimes pace the heart, as
needed.
The various leads are tunnelled to a pulse generator, which is
implanted in a pouch beneath the skin of the chest or abdomen. These
generators are typically a little larger than a wallet and have
electronics that automatically monitor and treat heart rhythms
recognized as abnormal. Newer devices are smaller and have simpler lead
systems. They can be installed through blood vessels, eliminating the
need for open chest surgery.
When an implantable cardioverter defibrillator
detects ventricular tachycardia or fibrillation, it shocks the heart to
restore the normal rhythm. New devices also provide overdrive pacing to
electrically convert a sustained ventricular tachycardia, and "backup"
pacing if bradycardia occurs. They also offer a host of other
sophisticated functions (such as storage of detected arrhythmic events
and the ability to do "noninvasive" electrophysiologic testing).
Implantable cardioverter defibrillators have been
very useful in preventing sudden death in patients with known, sustained
ventricular tachycardia or fibrillation. Studies are now being done to
find out how best to use them and whether they may have a role in
preventing cardiac arrest in high-risk patients who haven't had, but are
at risk for, life-threatening ventricular arrhythmias.
According to the American Heart Association Heart
and Stroke Statistical Update, in 1998 (the most recent statistics
available) there were 26,000 ICD procedures.
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More information at American Heart Association
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Patients in the study were age 65 years or older
with Medicare fee-for-service coverage and diagnosed with a heart attack
from 1999 through 2005.
The primary prevention group (136,421 patients -
65,917 men and 70,504 women) had either heart failure or cardiomyopathy
(a disorder of the heart muscle).
The secondary prevention group (99,663 patients -
52,252 men and 47,411 women) had cardiac arrest or ventricular
tachycardia (a cardiac arrhythmia).
In the 2005 primary prevention group, 32.3 per
1,000 men and 8.6 per 1,000 women received ICD therapy within 1 year of
entering the study.
Men in this group were about 3.2 times more likely
than women to receive an ICD. Among men and women alive at 180 days
after group entry, the risk of death in the subsequent year was not
significantly lower among those who received ICD therapy.
In the 2005 secondary prevention group, 102.2 per
1,000 men and 38.4 per 1,000 women received ICD therapy. After
controlling for various factors, men in this group were about 2.4 times
more likely than women to receive ICD therapy.
Among men and women alive
at 30 days after entry in this group, the risk of death in the
subsequent year was 35 percent lower among patients who received ICD
therapy.
"In this longitudinal analysis of Medicare
beneficiaries at high risk for sudden cardiac death, we found
significant sex differences in the use of ICD therapy from 1999 through
2005, the authors conclude.
Our findings in this cohort of elderly patients
differ from an earlier study that suggested a narrowing of the gap
between men and women, and they highlight the need for an improved
understanding of sex differences in patterns of care."
Lack of ICD Use Among All Ages: Women, Black Men
It has been well established that ICDs reduce the
risk of death for those suffering from irregular heart beats. About half
of all deaths from heart failure are sudden events thought to be
attributable primarily to these lethal arrhythmias.
This second study by Adrian F. Hernandez, M.D., M.H.S., of
Duke University School of Medicine, Durham, N.C., and others examined
the overall use of ICD therapy in patients with heart failure who were
at risk for sudden cardiac death.
It found that for some reason these life-saving
devices are not being used as often as possible, particularly in women
and black men.
Among patients in this study that were eligible for
ICD therapy, 4,615 (35.4 percent) had ICD therapy at discharge. ICDs
were used in 375 of 1,329 eligible black women (28.2 percent), 754 of
2,531 white women (29.8 percent), 660 of 1,977 black men (33.4 percent),
and 2,356 of 5,403 white men (43.6 percent).
After adjustment for patient characteristics and
hospital factors, compared with white men, the odds of ICD use were: 27
percent lower for black men; 38 percent lower for white women; and 44
percent lower for black women.
The analysis included 13,034 patients admitted with
heart failure and left ventricular ejection fraction of 30 percent or
less (a measure of how well the left ventricle of the heart pumps with
each contraction). Patients were treated between January 2005 and June
2007 at 217 hospitals participating in a quality improvement program.
"There are several potential factors that may
explain the disparities observed in this study. System inequities may
exist in the identification of eligible patients and delivery of ICD
therapy. Physicians may consider certain subgroups more prominently due
to a large number of white men in clinical trials. Patients may also
differ in preferences for ICD therapy across sex and race subgroups
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the authors write.
"Further research is needed to understand the
reasons for the disparities at the patient, physician, and hospital
levels. Programs for awareness and promotion of evidence-based use of
medical devices in heart failure are needed overall and for the
important subgroups studied here. Publicly reported measures regarding
ICD therapy should be considered
Editorial: Disparities in Use of ICDs
In an accompanying editorial, Rita F. Redberg,
M.D., M.Sc., of the University of California-San Francisco Division of
Cardiology, comments on studies regarding the use of ICDs.
"...the multibillion-dollar question is: Are too
few ICDs for primary prevention being implanted in women (and
minorities) or are too many ICDs being implanted in (white) men? The
important clinical and policy question may be not why women and black
Medicare beneficiaries are less likely to get an ICD, but which Medicare
beneficiaries will benefit from ICD at all?
To answer this question, studies must look beyond
reporting only process measures, such as implantation rates, and must
include clinical outcomes, such as survival and quality of life after
ICD implantation for primary and secondary prevention. By reporting the
first outcomes data for ICD in the Medicare population, the study by
Curtis et al should stimulate national dialogue on this crucial
question."
"Thus, in addition to their findings regarding
disparities in ICD use, the studies by Curtis et al and Hernandez et al
raise, perhaps inadvertently, a more serious concern. Their reports are
important, but only first steps in understanding how to optimize
delivery of cardiovascular health care in the United States.
Their work highlights the importance of outcomes
data for new therapies such as ICDs, reported according to sex and
race/ethnicity subgroups, to determine if all patients are benefiting
from health care advances."
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