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November 8, 2000
News this month
Study points to lower blood pressure target
In searching for ways to reduce the risk of heart attacks and
strokes among people with high blood pressure, medical researchers
studied 19,000 patients to determine what the target blood pressure
should be. Are there significant health benefits to be gained from
reducing blood pressure below the long-held baseline of 140/90 and
at what point is the benefit highest?
Medical researchers studied 19,000 patients
to determine what the target blood pressure should be.
The Hypertension Optimal Treatment (HOT) Study is one of the largest
intervention trials ever completed in hypertension. It was conducted
from October 1992 to August 1997 and involved 18,790 patients in
26 countries. The study also looked at the effectiveness of aspirin
in helping to control hypertension. Results were published in The
Lancet.
Subjects given three blood pressure targets
Participants in the study were 50 to 80 years old. They had an average
diastolic blood pressure of 105 millimeters (mm) of mercury (Hg)
and an average systolic blood pressure of 170 mm Hg. Forty-seven
percent of the subjects were women. Because of the near equal numbers,
the results of the study can be applied equally to both genders.
Results of the study can be applied
equally to both genders.
Participants were randomly assigned to three groups in which the
target diastolic blood pressure was 90, 85 or 80 mm Hg. About 53
percent of patients were being treated for hypertension prior to
the study. All previous antihypertensive medications were stopped.
To help patients reduce their blood pressure, felodipione, a long-acting
calcium channel blocker, was used. Angiotensin converting enzyme
(ACE) inhibitors and beta-blockers were added to the regimen of
about two-thirds of the subjects to help them attain their diastolic
blood pressure goal. For the aspirin study, 9,399 patients were
randomly assigned 75 mg/day of aspirin, and 9,391 were assigned
a placebo.
A 30 percent reduction in events including
death was observed at a mean diastolic blood pressure of 82.6.
Study findings
The lowest incidence of major cardiovascular events, a 30 percent
reduction in events including death, was observed at a mean diastolic
blood pressure of 82.6 mm Hg. Lowering blood pressure to 70 did
not seem to give much further benefit, but it also did not pose
any additional risk.
The most impressive and dramatic aspect of the study was the effect
on diabetics for whom cardiovascular disease is the major cause
of death. Diabetics in this study had a 2.5 times greater risk of
having an event associated with elevated blood pressure, even with
blood pressure targeted at less than 90 mm Hg, compared with the
general population. Aggressive treatment resulted in a 51 percent
reduction in risk of heart attack and stroke in the group using
80 mm Hg as a target versus the group using 90 mm Hg as a target.
The addition of aspirin reduced major cardiovascular events by
15 percent and heart attacks specifically by 36 percent. 
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Study shows blood pressure control
vitally important
The HOT Study, published in British journal The Lancet,
was not widely reported in the U.S., but it is a very important
study with treatment implications for millions of people. As many
as 50 million Americans have high blood pressure, and the numbers
are expected to increase as the Baby Boomers approach senior status
and as obesity and sedentary lifestyles continue to rise.
"Controlling blood pressure
is one of the best things we can do to protect our health."
High blood pressure or hypertension is called the silent killer
because it often creates no symptoms until the damage is done.
Elevated blood pressure causes the heart to work harder than normal,
making both the heart and arteries more prone to injury.
High blood pressure increases risk of:
- heart attacks
- strokes
- kidney failure
- damage to the eyes
- congestive heart failure
- arteriosclerosis
When high blood pressure exists with obesity, smoking, high blood
cholesterol levels or diabetes, the risk of heart attack or stroke
increases several times.
"Medications. . .are effective
in dramatically lowering blood pressure."
The good news is pharmaceutical companies are developing more
and better medications to treat high blood pressure, so physicians
have more tools to help their patients control high blood pressure.
Although medications were not the focus of the HOT Study, its
results indicate they are effective in dramatically lowering blood
pressure in both men and women from various racial and cultural
backgrounds and across a wide age span.
"There are significant health
benefits to be gained by bringing [blood] pressure. . .[down]
to 138.5/82.6.…"
How low can we go?
Hypertension has been defined as blood pressure of 140/90 or greater,
and our goal has been to help patients get their diastolic pressure
below that baseline. What the HOT study shows us is that there
are significant health benefits to be gained by bringing pressure
below that to 138.5/82.6 mm Hg. Cardiovascular complications were
30 percent less likely to occur in the subjects than in populations
that were six years younger on average than HOT subjects.
The study also disproved one theory that lowering blood pressure
too much might result in worse outcomes for some patientsthose
with severe heart disease or the very elderly. In fact, although
lowering blood pressure further (e.g. 120/70) did not seem to
give further benefit, it also did not pose any additional risk
even in the 3,000 subjects who showed evidence of significant
coronary artery disease.
Many physicians believe its unrealistic to try to achieve
a diastolic blood pressure below 80, but the study shows that
with appropriate medication, blood pressure can be lowered to
this level in the majority of patients.
Extra benefits for diabetics
The benefits are even greater for diabetics. Of the 1,501 patients
with diabetes, those in the 80 mm Hg group had half the risk of
a major stroke or heart attack compared with those in the 90 mm
Hg group. The study also found that 75 mg of aspirin in patients
with well-controlled blood pressure reduced the risk of heart
attack by 36 percent.
What have we learned?
- Lowering blood pressure to below 140/90 will help patients.
- Patients with diabetes should be treated more aggressively,
bringing blood pressure down to less than 80 if possible.
- Aspirin is useful in selected hypertensive patients.
- Calcium channel blockers are generally well tolerated and
effective, but it may be necessary to try a combination of drugs
on some patients to attain significant reductions in blood pressure.
Controlling blood pressure is one of the best things we can do
to protect our health. I advise everyone to have regular blood
pressure checks. Regular exercise and weight control will help,
but if you are diagnosed with high blood pressure, be sure and
talk with your physician about what can be done to reduce it.
Dr. Setaro is an attending cardiologist at Yale-New Haven
Hospital and Yale-New Haven Heart Center, as well as an associate
professor of medicine and director of the Cardiovascular Disease
Prevention Center at the Yale University School of Medicine.
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