Re-sync the beat to manage ‘heart block’

U. BUFFALO (US) — Heart failure patients with a condition called “heart block” get significant benefit from cardiac resynchronization therapy, according to the results of an eight-year-long clinical trial.

Anne B. Curtis, principal investigator of the Block HF clinical trial, presented results of the national, multicenter, randomized clinical trial yesterday at the American Heart Association Scientific Sessions 2012 meeting in Los Angeles, California.


“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,” says Curtis, chair of medicine in the University at Buffalo School of Medicine and Biomedical Sciences.

“The results of Block HF may lead to a reassessment of treatment guidelines for heart failure patients with heart block.”

In the 900-patient 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 mortality.

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,” explains Curtis.

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 US at a cost of somewhere between $20 and $56 billion per year. Of those, AV block affects more than 800,000 Americans and more than a million people worldwide.

Medtronic, Inc. sponsored the clinical trail.

Source: University at Buffalo