Some heart patients
vulnerable to mental stress
GAINESVILLE, Fla. Newswise — - The
fear of public speaking might cause some people to do more than just
break out in a cold sweat and battle stomach-churning butterflies -
it could prove to have consequences for their heart health.
University of Florida
cardiologists have identified a group of heart disease patients who
appear especially vulnerable to the physical effects of mental
Chronic anxiety, depression or
anger are widely recognized as raising the risk of heart attack,
hospitalization or sudden death in patients whose hearts suffer
dangerous decreases in blood flow during exercise testing. Even
something as simple as public speaking, doing mental arithmetic or
recounting an argument with a loved one can trigger a problem.
But until now, patients who trod
the treadmill without experiencing chest pain or restricted blood
flow had never been similarly scrutinized when it came to mental
stress. Yet what goes on in their heads could have consequences for
their hearts as well, UF researchers write in today's (March 7)
issue of the Journal of the American College of Cardiology.
of the heart patients they studied developed temporary changes in
heart rhythm or restricted blood flow when they were asked to
role-play a difficult interpersonal situation, even though their
hearts responded normally to exercise.
"Recently our group and some other
investigators have started to expand the population of patients that
we're looking at to try to explore what happens when mental stress
is applied," said David S. Sheps, M.D., a professor and associate
chairman of cardiovascular medicine at UF's College of Medicine and
the Malcom Randall Veterans Affairs Medical Center. "We believe the
phenomenon of mental stress-induced reductions in blood flow to the
heart is much more common than has been previously recognized."
In general, studies have shown
that as many as two-thirds of patients with coronary artery disease
who experience exercise-related reductions in blood flow to the
heart respond similarly to mental stress. These bouts often produce
no symptoms of chest pain and are rarely detectable on a standard
electrocardiogram. Yet last year UF researchers found that these
patients have a threefold greater risk of dying - as large a risk
factor as cigarette smoking or high cholesterol. Other studies have
linked stress experienced after mass disasters or natural
catastrophes with a rise in heart attacks and sudden death.
Psychological stress can leave the
heart more prone to developing arrhythmias or electrical instability
and the blood more prone to clotting. Stress appears to raise heart
rate and rapidly hike blood pressure, increasing the heart's need
for oxygen-rich blood, Sheps said. Yet less oxygen is supplied, in
part because coronary arteries constrict, impeding blood flow.
Doctors are concerned that this reaction to stress in the laboratory
is simply a snapshot of how patients respond to the stress of life
day in and day out.
In the current study, funded by
the National Institutes of Health and Bristol-Myers Squibb, UF
researchers studied 21 men and women with documented heart disease
who had no signs of reduced blood flow during exercise on the
standard exercise treadmill test or on nuclear perfusion scans of
the heart. Participants were given two minutes to prepare to deliver
a four-minute speech about a hypothetical stressful situation. Blood
pressure and electrocardiographic measurements were taken every
minute during the speech and for 10 minutes afterward. About half an
hour after the speech, participants underwent heart imaging scans
that reflected blood flow to the heart during the stressful
"These are patients who for
example might have had a severe lesion or a narrowing of one of the
coronary arteries and may have had a stent inserted; they're tested
after that and found to have no decreased blood flow with the
standard type of exercise testing," Sheps said. "However, we found
that about 30 percent of them had evidence of decreased blood flow
with the mental stressor."
In general, 20 percent to 30
percent of all patients cardiologists see could respond in a similar
fashion, Sheps estimated. Simply warning patients to avoid stress
because it's bad for them is not enough, he added.
"All of us are leading more and
more stressful lives, and it's hard to avoid it," he said. "We as
physicians need to find better ways to treat this phenomenon to
avoid having patients develop this type of response to an increased
UF researchers are now conducting
a related study involving more than 300 patients. They are
interested in replicating the findings and determining whether these
patients are more likely to suffer a heart attack, be hospitalized
or die from cardiac complications, Sheps added.
Why does mental stress restrict
blood flow in some patients even when exercise fails to have the
same effect? The effects of mental stress could predominantly affect
the heart's smaller vessels, causing them to spasm and temporarily
limiting blood flow, he speculated. In contrast, exercise tends to
affect the heart's larger vessels.
The findings suggest patients who
experience reductions in blood flow detectable when they are
experiencing mental stress but not during standard exercise
radionuclide testing may have a worse form of heart disease than
expected, cautioned David S. Krantz, Ph.D., chairman and a professor
of medical and clinical psychology at the Uniformed Services
University in Bethesda, Md.
"This patient group warrants
further study since they may have functionally more severe coronary
artery disease," he said.