Published November 7, 2012
Heart failure patients with heart block benefit significantly from cardiac resynchronization therapy (CRT), according to the results of an eight-year national clinical trial led by principal investigator Anne B. Curtis, MD.
Curtis, the Charles and Mary Bauer Professor and Chair of Medicine, presented findings from the multicenter, randomized BLOCK HF trial Nov. 6, during the American Heart Association’s Scientific Sessions 2012 meeting in Los Angeles.
According to Curtis, the trial confirms what clinicians and researchers have long hypothesized:
Heart failure patients with heart block fare better when both sides of their heart are resynchronized.
This procedure, known as biventricular pacing, involves
implanting a CRT device.
“The results of BLOCK HF may lead to a reassessment
of treatment guidelines for heart failure patients with heart
block,” Curtis says.
During the trial, sponsored by Medtronic, 342 patients underwent conventional right ventricular pacing and 349 underwent biventricular pacing with a CRT device.
Patients in the second group had a 26 percent reduction in the combined endpoint of mortality, heart-failure related urgent care and deterioration in heart function detected by echocardiography, Curtis notes.
The trial also showed a 27 percent relative risk reduction in
the composite endpoint of heart failure urgent care and all-cause
The BLOCK HF trial, which enrolled more than 900 patients, was
designed to address the best way to treat atrioventricular block, a
partial or complete block in the main “trunk” of the
heart’s electrical conduction system that affects more than
800,000 Americans and more than a million people worldwide.
“AV block prevents electrical impulses from reaching the bottom chambers of the heart, which then beat very slowly or not at all,” explains Curtis.
To treat it, many patients are implanted with a standard pacemaker with leads or pacing wires in the heart’s right atrium and right ventricle.
“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.”
Biventricular pacing with a CRT device, however, is more
complicated than implanting a standard pacemaker, making it a
procedure “clinicians don’t want to put patients
through without clear evidence of a benefit,” Curtis
“Today,” she adds, “we are showing that Block
HF does show that benefit.”
One of the world's leading clinical cardiac electrophysiologists
and an expert in cardiac arrhythmias, Curtis 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 authored a book on cardiac pacing.