The University of Iowa
The University of Iowa News Services Home News Releases UI in the News Subscribe to UI News Contact Us


Joint Office for Planning, Marketing and Communications
8788 John Pappajohn Pavilion
Iowa City IA 52242
(319) 356-3945

Release: March 21, 2002

UI researchers part of national implantable defibrillator study

University of Iowa Heart Care researchers participated in a landmark national study that found that patients left with weakened hearts following a heart attack who receive an implantable cardioverter defibrillator (ICD) are 30 percent more likely to still be alive two years later than patients without ICDs.

The research study was called the Multi-center Autonomic Defibrillator Implantation Trial, or MADIT II. Some1,232 patients were enrolled at 76 advanced heart centers nationwide over a four-year period. All of the patients had survived heart attacks that caused moderate left ventricular dysfunction, meaning that their hearts' ability to pump blood was reduced. One group was randomly assigned to receive an ICD, the other group received the best available conventional therapy.

After two years, the patients who had ICDs were almost one-third more likely to still be living than patients in the other group. That pattern continued through the next four years. The dramatic results led the study's independent data and safety monitoring board to stop the study earlier than planned.

"The MADIT II trial will revolutionize the way we care for such patients following a heart attack," said UI professor of internal medicine Brian Olshansky, M.D., a specialist in electrophysiology with UI Heart Care and an investigator involved with the study. "It's very exciting to know that we can so significantly improve survival with this advanced technology."

An ICD helps restore a normal heart rhythm in three ways, including anti-tachycardia pacing, or delivering a series of small electrical impulses to restore a normal heart rate and rhythm; cardioversion, or delivering a low-energy electrical shock at the same time to restore a normal heart rhythm; and defibrillation, which is the delivery of a high energy shock to the heart muscle to restore a normal rhythm. Vice President Dick Cheney is currently benefiting from an ICD.

More people – about 250,000 – die every year in the United States from serious, fast heart rhythms than from any other cause. ICDs have the ability to rescue patients from these heart rhythms.

"We already knew that ICDs worked very well in other patient populations, such as children with a high risk for sudden cardiac death," Olshansky said. "Now we have clear proof that patients who have a heart attack that leaves them with a heart that doesn’t pump blood properly will also live longer if they too receive an ICD."

An ICD is about the size of a pager. The device is implanted under the skin of the upper torso, with wires that carry electrical energy to the heart. The ICD constantly monitors the heart's rhythm. When it detects a very fast, abnormal heart rhythm, it delivers the appropriate electrical energy to the heart muscle to cause the heart to beat in a normal rhythm again.    

University of Iowa Health Care describes the partnership between the Roy J. and Lucille A. Carver College of Medicine at the UI and the UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide. Visit UI Health Care online at