Study Findings Challenge Current Clinical Practice
Clinical Trial Results Find Late Angioplasty after Heart Attack
Offers No Advantage Over Standard Drug Therapy
CHICAGO, Nov. 14 – About one-third of heart attack patients
do not receive treatment to open blocked arteries within the recommended
12-hour timeframe after a heart attack. Treatment such as angioplasty
or clot-busting drugs may not be given because patients arrive at
the hospital too late. For years it has been thought that late balloon
angioplasty of these patients’ arteries, if they are totally
blocked, is still beneficial and might prevent future heart failure,
another heart attack, or death. However, according to the results
of a large international multi-center clinical trial, stable patients
who had angioplasty plus stenting three to 28 days after a heart
attack did no better than patients on medical therapy (primarily
drug treatment) alone.
The Occluded Artery Trial (OAT) was funded by the National Heart,
Lung, and Blood Institute (NHLBI) of the National Institutes of
Health and is being presented today at a late-breaking clinical
trial session of the American Heart Association’s Scientific
Sessions 2006. The study is also published online on November 14
in the New England Journal of Medicine and in the journal’s
December 7 issue.
“These results challenge the long standing belief that opening
a blocked artery is always good. Instead, the study suggests that
late angioplasty is unnecessary in this circumstance. The good news
is there have been tremendous advances in drug therapy for heart
attack patients. Drug therapy is an important treatment option,”
said NHLBI Director Elizabeth G. Nabel, M.D.
“Our findings indicate that routine late opening of the heart
attack related coronary artery is not appropriate and should be
reserved only for certain patients such as those who are unstable
or continue to have chest pain following a heart attack. These results
should lead to lower rates of unnecessary coronary interventions
in this specific group of stable patients,” said Judith Hochman,
M.D., OAT study chair and Harold Snyder Family Professor of Cardiology,
Clinical Chief of Cardiology and Director of the Cardiovascular
Clinical Research Center, New York University School of Medicine
in New York City.
“In general, there is considerable individual variation in
the need for angioplasty or bypass surgery in patients who have
coronary artery disease.”
Hochman expressed concern about a trend in the OAT study toward
more heart attacks in the angioplasty group. Although the trend
was not statistically significant, she said, it needs to be studied
and the patients followed for a longer time to determine if the
trend continues or whether other trends emerge. According to Hochman,
it is not known whether the increase in heart attacks will lead
to an excess risk of heart failure or death or reduced quality of
life.
The OAT trial sought to determine whether performing balloon angioplasty
in a totally blocked coronary artery related to a heart attack three
to 28 days after the heart attack would benefit stable patients
and reduce the risk of future cardiovascular complications. In angioplasty,
a thin tube with a balloon or other device on the end is first threaded
through a blood vessel in the arm or groin (upper thigh) up to the
site of a narrowing or blockage in a coronary artery. Once in place,
the balloon is then inflated to push the plaque outward against
the wall of the artery, widening the artery and restoring the flow
of blood through it.
In OAT, a total of 2,166 patients in 27 countries were randomly
assigned to routine angioplasty with stenting combined with drug
therapy or to drug therapy alone. Most patients had blockages in
one coronary artery only.
Drug therapy for both groups included aspirin, blood-pressure lowering
ACE inhibitors, beta blockers, cholesterol-lowering therapy, and
clopidogrel, a drug given to patients with stents to prevent blood
clots. Patients assigned to undergo angioplasty were given the procedure
within 24 hours of treatment assignment. Stenting, placing a metal
mesh tube in the artery to keep it open, was recommended for the
patients given angioplasty. The primary endpoint or measured result
of the 5-year study was a composite of death from any cause, another
heart attack, or hospitalization for severe (Class IV) heart failure.
The OAT results found no statistically significant difference in
major cardiovascular events between the two groups over an average
of three years and up to five years. At four years, the rate of
death, heart attack, or serious heart failure was 17.2 percent in
the angioplasty group compared to 15.6 percent of the medical therapy
group. The results were consistent across study sites located in
the United States and in other countries.
The OAT investigators offer a possible explanation for the trend
toward more heart attacks in the angioplasty group. According to
Hochman, when someone has a 100 percent blocked artery, the heart
muscle may still be somewhat protected by small vessels that provide
blood flow from the other coronary arteries. “These vessels
are so small that if an easier blood flow path is reestablished
via angioplasty, they close down, either temporarily or permanently.
If the artery that had the angioplasty re-closes, these small vessels
would not be rapidly available to supply blood to your heart muscle
at the time of your next heart attack,” she said. In addition,
Hochman said that it is possible that some heart muscle damage due
to dislodging of clots and plaque at the time of the angioplasty
procedure counteracts other potential long-term benefits.
Each year, about one million people in the United States have a
heart attack and half of them (515,000) die. About one-half of those
who die do so within 1 hour of the start of symptoms and before
reaching the hospital. About one million angioplasty procedures
are performed in the US each year.
“There’s an important public health lesson to be learned
from the OAT trial results: seek care very early after heart attack
symptoms begin because that’s when there is a great deal of
benefit from angioplasty,” said Alice Mascette, M.D., chief
of NHLBI’s Heart Failure and Arrhythmias Branch and member
of the OAT study steering committee.
“And we should not forget that controlling the risk factors
for heart disease – such as high cholesterol and high blood
pressure - can go a long way toward preventing heart attack in the
first place.”
To interview Dr. Nabel, or study co-authors Dr. Mascette or Dr.
George Sopko of NHLBI, contact the NHLBI Communications Office at
301-496-4236; to interview Dr. Hochman, contact Pamela McDonnell,
Office of Public Affairs, NYU School of Medicine at 212-404-3555.
Part of the National Institutes of Health, the National Heart,
Lung, and Blood Institute (NHLBI) plans, conducts, and supports
research related to the causes, prevention, diagnosis, and treatment
of heart, blood vessel, lung, and blood diseases; and sleep disorders.
The Institute also administers national health education campaigns
on women and heart disease, healthy weight for children, and other
topics. NHLBI press releases and other materials are available online
at: www.nhlbi.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and Centers
and is a component of the U. S. Department of Health and Human Services.
It is the primary federal agency for conducting and supporting basic,
clinical, and translational medical research, and it investigates
the causes, treatments, and cures for both common and rare diseases.
For more information about NIH and its programs, visit http://www.nih.gov.
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