|
Drugs,
devices take on heart failure
News conference: 8:15–9 a.m., EST, Monday, March
18
(ATLANTA)—Advances in both pharmacology and technology
are improving the treatment of heart failure.
A
pair of large, randomized international trials presented at
the American College of Cardiology 51st Annual Scientific
Session in Atlanta, March 17–20, 2002, should decide
whether a new class of artery-dilating drugs has a future
as added therapy in patients with heart failure who are already
on standard medications.
The
two, identically designed ENABLE trials, one conducted in
North America and the other in Europe, “represents the
definitive trial of ‘endothelin antagonism,’ a novel
neurohormonal approach to the treatment of congestive heart
failure,” according to Dr. Milton Packer, of Columbia
Presbyterian Medical Center in New York City. “ENABLE”
stands for ENdothelin Antagonist Bosentan for Lowering cardiac
Events in heart failure.
In
the two trials, patients on conventional medications for moderate-to-severe
heart failure were randomly assigned also to receive either
a dummy placebo pill or bosentan, an oral endothelin-receptor
antagonist. The drug seemed to help such patients in early
small studies.
Some
artery-dilating medications improve symptoms of heart failure
by expanding blood vessels, which eases the heart’s blood-pumping
workload. If treatment with bosentan is found to lower patients’
risk of death or of hospitalization due to their illness,
it could “change the way physicians treat congestive
heart failure,” said Dr. Packer.
Dr.
Packer is scheduled to announce the results of ENABLE 1 and
ENABLE 2 here on Tuesday, March 19, at 8:48 a.m. during the
Late-Breaking Clinical Trials II (#412) session.
An
alternative approach, cardiac resynchronization therapy, helps
the heart’s main pumping chambers contract in proper
cadence. It has been shown to aid certain heart failure patients
by improving exercise endurance and enhancing well-being.
Now, further analysis of data from the Multicenter InSync
Clinical Evaluation (MIRACLE) suggests that resynchronization
therapy also reduces the need for hospitalization and may
improve survival. Separate research on the body’s physiological
response to cardiac resynchronization offers insight into
why this therapy is beneficial, while another study shows
that upgrading from a conventional pacemaker to a resynchronization
pacemaker is warranted.
Gauging
the effect of resynchronization therapy on hospitalization
and death was an important objective of the MIRACLE study.
To do this, researchers evaluated more than 450 patients with
moderate-to-severe heart failure and an abnormal delay in
the conduction of electrical impulses in the heart. In half
the patients, they activated the resynchronization device—a
special type of pacemaker that governs the beating of both
the right and left ventricles—and in the other half,
left it inactive (William T. Abraham, #839-2). Over six months,
they observed that patients whose resynchronization pacemakers
had been activated were about 40 percent less likely to be
hospitalized or to die when compared to the control group,
a statistically significant difference. (Original presentation
on March 18, 4:15–4:30 p.m.)
One
of the ways cardiac resynchronization may work to improve
the health of heart failure patients is by reducing the levels
of harmful chemicals released by the body in response to injury
or stress. In a small study from the University of Florence
in Italy (Michael R. Hill, #1017-119), researchers
observed a significant correlation between reductions in certain
forms of tumor necrosis factor and improvements in the volume
of blood the heart was able to pump with each contraction,
as well as in the quality of life. (Original presentation
on March 17, at a 10–11 a.m. poster session.)
Whether
the benefits of cardiac resynchronization warrant upgrading
to the new device in patients who already have a conventional
pacemaker was the subject of a study from University Hospital
in Rennes, France (Jean-Claude Daubert, #815-3). Researchers
found that implanting a resynchronization pacemaker was worthwhile,
producing similar improvements in heart function, exercise
capacity, and symptoms when compared to patients who did not
already have a pacemaker. (Original presentation on March
18 at 11:30–11:45 a.m.)
Moderator:
Dr. Sharon Hunt, Stanford University Medical Center, Palo
Alto, Calif.
Complexity of atrial fibrillation drives research innovation
News conference: 11–11:45 a.m., EST, Monday, March 18
(ATLANTA)—Atrial
fibrillation is the most common cardiac arrhythmia—and
surely the most vexing. In fact, it so frequently defies attempts
to restore a normal rhythm that many cardiologists wonder
whether it’s worthwhile trying, preferring instead to
prescribe a menu of medications to slow the heart rate to
a tolerable speed and prevent stroke. The debate over which
is the superior approach—rhythm control or rate control—is
the focus of two potentially groundbreaking studies being
reported at the American College of Cardiology 51st Annual
Scientific Session in Atlanta, March 17–20, 2002. Separate
studies examine catheter-based approaches to eliminating the
source of the arrhythmia with radiofrequency energy and a
novel device that, when implanted in the heart, may cut the
risk of stroke by preventing blood clots from forming.
One
of the largest-ever comparisons of two methods for managing
patients with atrial fibrillation, an abnormal rhythm of the
heart’s smaller upper chambers, could change the way
physicians treat an increasingly common health problem.
Normally
the two upper heart chambers, the atria, efficiently pump
blood into the two larger chambers, the ventricles. But atrial
fibrillation impairs ventricular filling because the atrial
muscle cells don’t contract in synchrony, which can sometimes
lead
to potentially fatal ventricular rhythms. Atrial fibrillation
can also promote formation of clots that can trigger strokes.
Physicians can use drugs to restore proper atrial rhythm (rhythm
control) or, instead, to control the ventricular heart rate
(rate control). But neither method has been shown to be safer
or more effective than the other. That could change.
In
the Atrial Fibrillation Follow-up Investigation of Rhythm
Management (AFFIRM), more than 4,000 elderly patients with
atrial fibrillation who were at high-risk for stroke or death
were randomly managed with either rhythm control or rate control.
All patients received blood thinners to lower the risk of
stroke, which is standard therapy.
“AFFIRM
is the largest trial of its kind ever conducted, and the first
to use death as a primary outcome measure,” said Dr.
D. George Wyse, of the University of Calgary in Alberta, Canada.
Dr. Wyse is scheduled to present its results Monday, March
18, at 9:15 a.m. at the American College of Cardiology 51st
Annual Scientific Session.
Patients
with atrial fibrillation can be treated with either shocks
or medications to restore normal atrial beats. But physicians
may alternatively choose to restore adequate blood flow with
drugs that regulate contractions of the heart’s lower
chambers, the ventricles. Now a study has directly compared
these methods—electrical shocks as needed to restore
normal heart rhythm or drug therapy to control the rate of
ventricular beats—to determine whether one or the other
might serve patients better.
Normally
the atria rhythmically and efficiently fill the ventricles
with blood. But this process is impaired by atrial fibrillation,
in which the atrial muscle cells contract in an uncoordinated
way. Without effective treatment, the disorder can lead to
the formation of clots that can cause strokes, or, occasionally,
trigger abnormal ventricular rhythms that could become fatal.
The
RACE study is the first study to compare electric-shock rhythm
control and ventricular rate control only in patients with
persistent atrial fibrillation—excluding patients with
the less serious intermittent form of the rhythm abnormality,
according to Dr. Isabelle C. Van Gelder, a lead investigator
with the study. All patients in the RACE (Rate Control vs.
Electrical Cardioversion for Persistent Atrial Fibrillation)
study were given blood-thinning medications to help prevent
stroke, observed Dr. Van Gelder,
of the Interuniversity Cardiology Institute of The Netherlands,
Utrecht.
RACE
principal investigator Dr. Harry J. Crijns, of the University
Hospital Maastricht in The Netherlands, is slated to disclose
the trial’s findings Monday, March 18, at 9:30 a.m. at
the American College of Cardiology 51st Annual Scientific
Session.
An
alternative approach to treating atrial fibrillation targets
the abnormal tissue that sparks the arrhythmia. After threading
an electrode-tipped catheter into the heart, the electrophysiologist
delivers radiofrequency energy to the offending site, which
often is located in the opening of the pulmonary veins. The
resulting scar is intended to eliminate the abnormal electrical
impulses or block their spread through the upper chambers
of the heart.
Researchers
from the University of Pennsylvania Health System in Philadelphia
set out to determine which of these two options was best:
localized destruction of arrhythmia triggers in the pulmonary
vein or isolation of the vessel with a ring of scar tissue
(Francis E. Marchlinski, #885-6). They found that isolation
of the pulmonary vein produced the best immediate results,
eliminating atrial fibrillation in nearly all patients. After
two months, however, the procedure lost some of its effectiveness,
with about one in five patients again experiencing the arrhythmia.
(Original presentation on March 20, 9:45–10 a.m.)
Whether
pulmonary vein isolation should be considered in patients
with atrial fibrillation complicated by impaired heart function
was the subject of a preliminary study from the Cleveland
Clinic Foundation (Alejandro Perez-Lugones, #885-3). The investigators
concluded that it was equally as safe and effective in a group
of patients with a left ventricular ejection fraction averaging
less than 40 percent as in those with normal heart function.
(Original presentation on March 20, 9–9:15 a.m.)
Moderator:
Anne B. Curtis, MD, FACC, University of Florida, Gainesville,
Fla.
Studies
on heart disease and diabetes mix caution with hope
News conference: 12–12:45 p.m., EST, Monday, March
18
(ATLANTA)—Diabetes
is often said to be a form of heart disease, so terrible is
its toll on the cardiovascular system. Studies being presented
at the American College of Cardiology 51st Annual Scientific
Session in Atlanta, March 17–20, 2002, highlight this
increased cardiovascular risk but also offer hope that advances
in prevention and medical therapy can improve the health and
survival of patients with diabetes. In addition, results of
a national patient survey commissioned by the American Diabetes
Association (ADA) and the ACC will be presented.
Certain
medications used for treating type 2 diabetes place patients
at greater risk for heart failure, according to a study from
Policy Analysis in Brookline, Mass. (Thomas Delea, #858-3).
The medications belong to the glitazone family and are known
by the trade names Rezulin, Avandia, and Actos (troglitazone,
rosiglitazone, and pioglitazone, respectively). The study,
which drew its data from health insurance claims, compared
clinical outcomes in more than 8,000 people with type 2 diabetes
who were treated with a glitazone and more than 41,000 who
were not. Researchers found that, over a follow-up of nearly
nine months, the risk of developing heart failure was increased
by more than half in patients taking a glitazone, even after
the data were adjusted for differences in the clinical history
and average age of patients in the two groups. (Original presentation
on March 19, 11–11:50 a.m.)
People
with diabetes who experience unstable angina or a type of
heart attack known as non–ST segment elevation myocardial
infarction (NSTEMI) are far more likely to die than people
without diabetes, a new study has shown (Marco Roffi, #840-4).
Researchers at the Cleveland Clinic Foundation in Ohio and
Duke Clinical Research Institute, Durham, North Carolina,
pooled data from four large studies on the treatment of acute
coronary syndromes that together enrolled more than 5,400
patients with diabetes. They found that diabetes increased
the risk of dying within 30 days by more than half. (Original
presentation on March 19, 9:15–9:30 a.m.)
Diabetic
patients are also at higher risk than other patients after
another type of heart attack, known as ST-elevation myocardial
infarction. Whether advances in therapy have improved that
picture over time was the subject of a study from the Cleveland
Clinic Foundation in Ohio (Hitinder S. Gurm, #1074-33). Investigators
compared the outcomes of 92,000 diabetic patients enrolled
in three sequential heart attack trials. They found that diabetic
patients were consistently more likely than other patients
to die in the hospital or within the following month, but
that the increased use of beta blockers and angiotensin-converting-enzyme
inhibitors in the most recent trial improved survival. (Original
presentation on March 18 at a 10–11 a.m. poster session.)
While
most diabetics are well aware of the disease’s complications
such as blindness and amputation, results of a survey commissioned
by the ADA and the ACC demonstrate that patients remain uninformed
of diabetes’ more life-threatening complications, heart
disease and stroke—the leading causes of death for the
16 million diabetic Americans. Dr. John Buse, of the ADA,
will address the specific findings of the survey that were
released in mid-February during a news conference with U.S.
Department of Health and Human Services Secretary Tommy Thompson.
Moderator:
Dr. Robert Rosenson, Northwestern University Medical School,
Chicago
The
American College of Cardiology, a 28,000-member nonprofit
professional medical society and teaching institution, is
dedicated to fostering optimal cardiovascular care and disease
prevention through professional education, promotion of research,
leadership in development of standards and guidelines, and
the formulation of health care policy.
|
