Implanted defibrillators saving lives

Implanting cardioverter-defibrillators reduces death by 23 percent in people with chronic heart failure, according to a study published Thursday in The New England Journal of Medicine.

Researchers at both University Hospital and LDS Hospital participated in the large national study, sponsored by the National Institutes of Health.

The study found that as many as 600,000 Americans with heart failure could experience sudden cardiac arrest, a condition the defibrillator protects against. It is implanted beneath the skin in the chest and stops potentially chaotic heart rhythms with an electric shock.

The reduction in death with the defibrillator was a "pretty dramatic improvement," said Dr. Edward Gilbert, professor of medicine at the U. "And when they looked at the patients who seemed to derive the greatest benefit, it was the people we would otherwise have characterized as most stable. This expands who really is a candidate for defibrillator therapy."

Such therapy is traditionally reserved for those with sustained arrhythmias that caused unconsciousness, or those who had already survived a "sudden-death" episode, where the heart stops and the person is brought back with CPR or an electric shock.

Heart failure is a progressive, debilitating condition where the lower chambers of the heart can no longer pump enough blood to meet the circulatory system's needs. It is characterized by "impaired vigor of contraction" of the heart's left ventricle, which normally ejects 60 percent of the blood it holds each time it pumps, said Dr. Dale G. Renlund, medical director of LDS Hospital's heart failure program and one of the hospital's principal investigators for the study.

The clinical trial was created because heart specialists had all treated heart failure patients who seemed to be doing very well and then dropped dead unexpectedly from chaotic heart rhythms.

The researchers decided to see if using either a medication used to stabilize heart rhythm or a defibrillator, which delivers an electric shock to interrupt such rhythm, would help.

The 2,521 test subjects were heart failure patients whose left ventricles were ejecting less than 35 percent but who had no other history or symptoms that seemed to require a defibrillator. They were randomly assigned to receive a defibrillator (those in the study were made by Medtronic), a commonly prescribed anti-arrhythmia drug called amiodarone, or a placebo. All of the study participants continued to receive their standard heart-failure care such as Beta blockers, ACE inhibitors and diuretics.