Abnormal Heart Rhythm May Be
Predicted By Risk Score
Weighing a combination of risk factors could
help doctors predict which patients are the most
likely to develop atrial fibrillation, says a study
reported in the medical journal The Lancet.
September 2009
Abnormal Heart Rhythm May
Be Predicted By Risk Score
An Increase In AF Prompts
Probe
A Closer Look At Risk Factors
Risk Factors Can Be
Predictive
Promise for Preventing AF
Someday
The Clinical Impact Remains
Uncertain
Researchers have developed a risk score that
might one day help prevent what has become
the most common type of abnormal heart
rhythm in the US, affecting about 2.2 million
people.
Learning More about Heart
Rhythm
Online Resources
An Increase In AF Prompts Probe
Atrial fibrillation, or AF, is a condition that
causes the upper chambers of the heart to beat
erratically, which hinders the heart's ability to
pump blood. It can increase the risk of stroke,
heart failure, and dementia. According to the
American Heart Association, AF can be controlled
with medication or surgical procedures, but
there is no way to keep it from developing so
far.
"We know a lot about the prevention of many
different types of vascular disease, but there
has been very little attention paid to preventing
AF," says lead researcher Dr. Emelia Benjamin,
at Boston University School of Medicine.
But attention might be warranted, since the
condition is on the increase in the US. By 2050,
almost 16 million Americans will have AF, says
Dr. Benjamin. This dramatic increase is partly
due to people living longer and developing
diseases associated with aging. In addition,
people with heart disease are also living longer.
Learning More about
Heart Rhythm
One of the most common
abnormal heart rhythms is
premature ventricular
beats, or PVCs.
PVCs occur when the
ventricles beat sooner than
they should.
This means that the
ventricle is contracting and
pumping out blood before
the atrium above it has
completely pumped its
blood volume into the
ventricle.
Most of the time, PVCs are
harmless. In fact, almost
everyone has them at one
time or another.
A Closer Look at Risk Factors
"The risk factors for AF are known, but they
tend to be looked at one at a time, and there
has been no way of predicting an individual's
risk for the disease, says Dr. Benjamin."
"We developed a risk score for new-onset AF
that would work in a doctor's office, or a person
could use it to figure out their risk of AF," she
explains.
The risk factors for AF include older age, being
male, being overweight, hypertension, having a
heart murmur, and a history of heart failure.
"These have previously been described, but not
put together in a risk score," she notes.
Risk Factors Can Be Predictive
For the study, Dr. Benjamin's team, which
included Dr. Renate Schnabel from the
Johannes Gutenberg-University in Mainz,
Germany, collected data on 4,764 people who
participated in the Framingham Heart Study.
These individuals were ages 45 to 95 and did
not have AF. The selection of people for the
study was made from examinations done
between June 1968 and September 1987.
Over 10 years of follow-up, 10 percent of the
people developed AF. The strongest factors that
predicted the risk of developing AF were age,
sex, weight, high blood pressure, being treated
for high blood pressure, heart murmur, and
heart failure.
In addition, researchers found that the time
between the P and R waves (PR interval), as
seen on an electrocardiogram, was also a
significant predictor of AF. The risks associated
with AF were also found to vary with age. For
example, those over 65 were more than 15
times more likely to develop AF than people
under 65, the researchers note.
Promise for Preventing AF Someday
However, if PVCs occur too
frequently (more than
several times per minute),
the heart is unable to
pump an adequate volume
of blood to the body, which
can cause symptoms such
as weakness, fatigue,
palpitations, or low blood
pressure.
Other types of rhythm
problems can have similar
effects.
Problems may occur when
the heart beats too fast,
too slow, or with an
irregular rhythm.
But whether the heart is
beating too fast, too slow,
or too irregularly, the
effects are often the same
as one or more of those
described above. Some
additional examples of
rhythm problems include:
atrial fibrillation - occurs
when the atria beat
irregularly and too fast
ventricular fibrillation occurs when the ventricles
beat irregularly and too
fast
bradycardia - occurs when
the heart beats too slow
tachycardia - occurs when
the heart beats too fast
heart block - occurs when
the electrical signal is
delayed or blocked after
leaving the SA node. There
are several types of heart
blocks, and each one has a
distinctive
This risk score may help physicians and patients
determine the risk for AF, says Dr. Benjamin.
More important, this risk score might help
doctors develop a way to prevent the condition.
"Before you can prevent something, you have to
know how to predict it," explains Dr. Benjamin.
This risk score will be useful first to help
patients understand their risk, second to
provide information for clinical trials, and third
to evaluate other ways of predicting AF.
Dr. David Brieger, at the University of Sydney in
Australia and author of an accompanying
journal comment, says this study could be a
first step in finding a way to prevent AF.
"It may be possible to identify strategies,
pharmacologic and others such as lifestyle, to
prevent the onset of atrial fibrillation in highrisk patients," says Dr. Brieger.
Atrial fibrillation is a potentially disabling
condition that is increasing in frequency and
placing an increased burden on health care
resources, says Dr. Brieger.
"Preventing this condition would have immense
value. Identifying patients at high risk of
developing the condition is an important initial
step in this process," he adds.
The Clinical Impact Remains Uncertain
Dr. Gregg C. Fonarow, at the University of
California, Los Angeles, says it is not clear how
this risk score would change clinical practice.
"While helpful from a research standpoint, the
potential clinical utility of this risk score requires
validation in other populations and further
study," says Dr. Fonarow.
"It remains untested whether detection of
increased risk of AF will result in any change in
care or improve clinical outcomes."
Always consult your physician for more
information.
electrocardiogram (ECG)
tracing.
Some dysrhythmias,
however, occur only
intermittently, and cannot
be seen on a routine ECG
or on a more sophisticated
type of ECG, such as a
signal-averaged ECG or a
Holter monitor procedure
(a prolonged recording of
the heart rhythm over 24
hours or longer).
If the physician suspects a
problem with the heart's
conduction system and
cannot adequately
diagnose the problem with
other tests or procedures,
then he/she may also
decide that an
electrophysiology study is
appropriate.
An electrophysiology
study(EP) is a more
invasive test used to
provoke arrhythmia in
order to identify the cause
and location of an
abnormal electrical
impulse.
Always consult your
physician for more
information.
Online Resources
(Our Organization is not
responsible for the content
of Internet sites.)
American Heart
Association
Heart Rhythm
Foundation
Heart Rhythm Society
National Heart, Lung,
and Blood Institute
(NHLBI)
The Heart Truth
Campaign
The Lancet Development of a risk
score for atrial
fibrillation (Framingham
Heart Study): a
community-based
cohort study