Cardiology experts at Johns Hopkins have issued
interim guidelines for physicians on how best to treat low
levels of HDL cholesterol, the so-called good cholesterol,
which helps keep arteries clear from the buildup of LDL
cholesterol, the so-called bad cholesterol. More than 54
million Americans are estimated to need higher levels of
HDL, according to the American Heart Association.
In an article published in The New England Journal
of Medicine online Sept. 22, the Johns Hopkins
researchers report that existing strategies to prevent
heart disease have not addressed the best means to raise
HDL cholesterol and instead have focused heavily on
lowering LDL cholesterol, which leads to plaque formation
and narrowing of the arteries that can cause heart
attack.
"We have reached a turning point in the prevention of
coronary heart disease, from an emphasis during the last 15
years on lowering LDL cholesterol levels to an emphasis in
the next decade on raising levels of HDL cholesterol," said
article lead author and cardiologist Roger Blumenthal, an
associate professor and director of the Ciccarone
Preventive Cardiology Center at the School of Medicine and
its
Heart Institute.
Existing guidelines from the U.S. National Institutes
of Health and its National Cholesterol Education Program
primarily emphasize lowering LDL cholesterol to control
blood lipid levels without considering the alternative of
raising HDL cholesterol as the primary or even secondary
goal, Blumenthal said.
However, Blumenthal said, every single milligram per
deciliter increase in HDL cholesterol lowers a person's
risk of suffering a fatal heart attack by about 3 percent;
low levels of HDL cholesterol are known to increase overall
risk of dying from heart disease and, specifically, to
increase risk of arteries narrowing again after angioplasty
surgery to clear them. Low levels of HDL cholesterol, he
said, are defined as less than 40 milligrams per deciliter
of blood in men and 50 milligrams per deciliter in
women.
In the NEJM report, Blumenthal and a fellow expert,
nurse practitioner Dominique Ashen, an assistant professor
at the School of Nursing, provide a comprehensive review
and summary of the 50 most significant research studies on
how best to manage people's HDL cholesterol levels through
modification of lifestyle risk factors for developing heart
disease and use of drug therapy.
In addition, the researchers support their summary
findings with a concise table listing heart medications
with guidelines about how and when the drugs — niacin,
fibrates and statins, or various combinations — can be used
to raise HDL cholesterol levels. Also provided in the table
are details on the drugs' chemical properties, or mechanism
of action, and possible side effects.
However, Blumenthal and Ashen pointed out that
research to date has not yet clearly distinguished which
reductions in risk from heart disease are due to drug gains
in HDL levels or other direct effects on the arteries.
"That has been responsible for delaying revisions to
national guidelines on HDL cholesterol," Blumenthal
said.
Using a recent patient case study from Johns Hopkins
involving a 41-year-old man with low levels of HDL
cholesterol (28 milligrams per deciliter), the researchers
reviewed how over a period of three years his HDL levels
were raised to above normal by modifying his lifestyle risk
factors. These modifications included making sure the
patient engaged in regular exercise, ceased smoking,
assumed control over his weight as measured by body mass
index, limited alcohol intake and monitored dietary fat
intake. The patient lost nearly 50 pounds while undergoing
treatment.
To raise HDL cholesterol levels, the researchers
recommend a regular exercise program of brisk aerobic
exercise for 30 minutes several times per week, if not
every day.
Quitting smoking, they said, provides an average
increase in HDL levels of 4 milligrams per deciliter. Aids
such as drug therapy, nicotine replacement products and
counseling can help patients quit.
Weight control is also highlighted as critical to
raising HDL levels, with the researchers noting that every
kilogram of weight lost raises a patient's HDL levels by an
average 0.35 milligrams per deciliter. A reasonable weight
loss goal for overweight or obese patients, they suggest,
is one pound per week, with a target body mass index of
less than 25.
Mild to moderate consumption of alcohol, no more than
one to two drinks per day, they said, has been shown to be
beneficial in raising HDL levels by an average of 4
milligrams per deciliter, irrespective of type of alcohol
consumed. But the researchers cautioned that the potential
risks here may outweigh the benefits in people with liver
or addiction problems.
For dietary control, the researchers recommend a diet
low in saturated fat and rich in the polyunsaturated fatty
acids found in foods such as oils (olive, canola, soy and
flaxseed), nuts (almonds, peanuts, walnuts and pecans),
cold-water fish (salmon and mackerel) and shellfish.
Consumption of carbohydrates, they say, should be
restricted because high glycemic products, such as
processed cereals and breads, are associated with lower HDL
levels.
In the report, the researchers cite niacin, also
called nicotinic acid or vitamin B3, as the most effective
medication for raising HDL cholesterol, leading to
increases of 20 percent to 35 percent. Fibrate therapy is
also effective, they said, producing an average increase of
10 percent to 25 percent. Statins are the least effective
of the three drug classes, used primarily to reduce LDL
cholesterol, raising HDL levels by 2 percent to 15 percent.
When used in combination, low-dose statins and high-dose
niacin have been shown to produce benefits of 21 percent to
26 percent.
"Our report offers people interim guidelines on how
best to manage HDL cholesterol levels while awaiting the
results of national clinical trials, which could prove more
definitive," said Ashen, who was lead author of the
article. "These guidelines also offer a good description of
the problem posed by low levels of HDL cholesterol, along
with details on how HDL cholesterol metabolism works in the
body with LDL cholesterol.
The guidelines, she said, "should help physicians and
nurses to manage their patients' blood lipid levels,
including HDL cholesterol, with drug therapies currently
available, and should help prepare them to manage future
therapies, expected to be developed within the next five
years, that focus on raising HDL-cholesterol levels."
Funding support for the researchers was provided by
the Maryland Athletic Club & Wellness Center Charitable
Foundation.