BUFFALO, N.Y. -- Heart failure patients with a condition called
"heart block" derive significant benefit from cardiac
resynchronization therapy (CRT), according to the results of the
Block HF clinical trial, presented today at the American Heart
Association Scientific Sessions 2012 meeting in Los Angeles.
Anne B. Curtis, MD, Charles and Mary Bauer Professor and Chair
of Medicine in the University at Buffalo School of Medicine and
Biomedical Sciences and principal investigator of Block HF,
presented results of the eight-year-long, national, multicenter,
randomized clinical trial sponsored by Medtronic, Inc., which
enrolled more than 900 patients. Curtis discusses the results in
this video at http://youtu.be/agALz_NZDJ8.
"These findings confirm what some clinicians and researchers
have hypothesized for some time -- that heart failure patients with
heart block do better when both sides of the heart are
resynchronized, called biventricular pacing, using a cardiac
resynchronization therapy (CRT) device," she says. "The results of
Block HF may lead to a reassessment of treatment guidelines for
heart failure patients with heart block."
In the trial, 349 patients underwent biventricular pacing with a
CRT device and 342 patients underwent the conventional right
ventricular pacing. Patients who underwent biventricular pacing had
a 26 percent reduction in the combined endpoint of mortality,
heart-failure related urgent care and deterioration in heart
function detected by echocardiography.
There also was a 27 percent relative risk reduction in the
composite endpoint of heart failure urgent care and all-cause
The Block HF trial was designed to address the best way to treat
atrioventricular block (AV block), a partial or complete block in
the main "trunk" of the heart's electrical conduction system.
"AV block prevents electrical impulses from reaching the bottom
chambers of the heart, which then beat very slowly or not at all,"
To treat AV block, many patients are implanted with a standard
pacemaker with leads or pacing wires in the top chamber (right
atrium) and the bottom chamber (right ventricle) of the heart. "But
that fix can lead to other problems," Curtis says, "such as
creating less synchrony between the left and right ventricles of
the heart, making their heart failure symptoms even worse."
Researchers and clinicians have hypothesized that better
outcomes might result from pacing both the left and right
ventricles of the heart, called biventricular pacing, which
involves implanting a cardiac resynchronization therapy device.
"Implanting these devices is more complicated than putting in a
standard pacemaker, something clinicians don't want to put patients
through without clear evidence of a benefit," says Curtis. "Today,
we are announcing that Block HF does show that benefit."
Heart failure affects approximately 6 million people in the U.S.
at a cost of somewhere between $20 and 56 billion/year. Of those,
AV block affects more than 800,000 Americans and more than a
million people worldwide.
Curtis, a UB faculty member since 2010, is one of the world's
leading clinical cardiac electrophysiologists and an expert in
cardiac arrhythmias. Her clinical research has significantly
advanced knowledge of human cardiac electrophysiology and heart
Her research interests include clinical trials in implantable
device therapy for prevention of sudden cardiac death and
management of heart failure, as well as clinical trials in atrial
fibrillation. She has been principal investigator, co-investigator,
sponsor or steering committee member on 85 research studies and
clinical trials and she has written more than 250 peer-reviewed
manuscripts, book chapters, reviews and editorials. She also is
author of a book on cardiac pacing.