Implantable defibrillator cuts heart attack risk of sudden death by 31%

Researchers at Loyola University Health System, Maywood, Ill., and the University of Rochester Medical Center, Rochester, N.Y., found that the previously demonstrated survival benefit of ICDs following a heart attack can last up to 15 years.

The ICD is a small electronic device, implanted in the chest, which shocks the heart back into a healthy rhythm if it detects an abnormal heartbeat. Arrhythmia (irregular heartbeat) is a major cause of death after a heart attack.

“In contrast to earlier studies which found that heart attack patients appeared to be out of danger if they survived at least six to 12 months following a heart attack, this new study shows that mortality risk increases with time,” said co-author Dr. David Wilber, director of cardiology, Loyola University Health System; and director of Loyola’s Cardiovascular Institute.

“Studies in the 1970s and 1980s indicated that patients with severe heart muscle damage had the greatest risk of sudden death in those first six to 12 months,” said Wilber, the George M. Eisenberg professor of cardiovascular sciences, department of medicine, Loyola University Chicago Stritch School of Medicine, Maywood.

“But medical advances in the past 10 years improved patients’ early survival,” Wilber said. “The challenge now is meeting the needs of patients at increased risk for death from arrhythmias and heart failure over the long-term.

“If the heart is not started within six minutes after an episode, survival is low,” said Wilber, noting that it may take longer than six minutes for emergency help to arrive at the scene. “In contrast, an implantable defibrillator provides immediate treatment.”

Researchers at Loyola and University of Rochester Medical Center studied more than 1,100 heart attack patients who had severe heart muscle damage. Participants’ were identified as being at risk for death because the heart muscle pumping action was poor.

These patients had enrolled in the study between three- and 159 months after their heart attack. A total of 699 patients received an ICD; another 460 patients received conventional care.

Wilber and colleagues followed the patients for up to 53 months. The researchers found the mortality rate consistently lower in the ICD-treated group compared to the conventionally treated group.

“We now can identify patients with a high probability of sudden death by a simple test of heart muscle function,” said Wilber. “These people are the ones who should be treated with an implantable defibrillator as a preventive measure.”

Co-authors of the study with Wilber are Dr. Wojciech Zareba, W. Jackson Hall, Mary W. Brown, Dr. Albert C. Lin, Mark L. Andrews, Dr. Martin Burke and Dr. Arthur J. Moss.

Loyola University Health System’s heart program is ranked as the top program in Illinois, according to U.S. News & World Report’s annual survey of more than 6,003 hospitals nationwide.

Loyola's 3,500-square-foot Sally & Jim Dowdle Electrophysiology Laboratories includes two dedicated fluoroscope suites equipped with state-of-the-art multichannel digital recording systems, 3-D mapping systems, intracardiac echocardiography and a laser system.