Defibrillator Shocks Signal Increased Death Risk, Study Finds

-Bloomberg

09/04/2008- Heart failure patients who get a lifesaving shock from implanted cardiac defibrillators are five times as likely to die in the coming months and years, typically from progression of the disease, researchers said.

The shocks provide an early warning system for patients and doctors, signaling that the underlying heart condition may be worsening, according to the report released today by the New England Journal of Medicine. A second study found that defibrillators temporarily boost psychological well-being, easing concerns that the devices would reduce quality of life.

About 5 million Americans have heart failure, a chronic condition in which the organ isn't able to pump enough blood to fuel the body. Studies show the devices, known as ICDs, significantly prolong lives by shocking a stopped heart back into a normal rhythm. The new findings shed light on how patients fare after they get a jolt from the $30,000 implanted devices sold by Medtronic Inc., Boston Scientific Corp. and St. Jude Medical Inc.

``These patients had their lives saved, and they are now clearly identified as a high-risk population,'' said Jeanne Poole, director of the electrophysiology program at the University of Washington in Seattle, in a telephone interview today. ``We need to think of what else we can do to minimize that patient's risk of death in the near term and try to prolong their lives as much as possible.''

The results come from an analysis of 811 patients in the Sudden Cardiac Death in Heart Failure Trial, including 269 patients who received at least one shock within about 4 years of getting an implanted defibrillator. Those who got a lifesaving shock were 5.7 times more likely to die than those whose devices didn't go off. Patients who got a shock that wasn't needed to revive them, were twice as likely to die, the researchers said.

Abnormal Rhythm

These patients who received inappropriate shocks often had another, nonfatal type of erratic heart rate, such as atrial fibrillation, Poole said. The abnormality was likely responsible for the increased risk of death, rather than damage from the shock, she said. In the study, patients who were both revived by the devices and received unnecessary jolts were most likely to die, with an 11-fold increased risk, the study found.

``There are 200,000 to 300,000 people who die from sudden cardiac arrest each year in this country,'' Poole said. ``We aren't offering defibrillators to enough patients who are at risk. It's a tragic cause of death that can be prevented.''

One reason some patients don't get the devices is because they fear the therapy could avert a quick, painless death and drag out the process. Others worry the devices, which can be seen through the skin, and the shocks they deliver might erode the quality of their life. The second study, an analysis of 2,521 patients also enrolled in the SCD-HeFT trial, eased those concerns, the researchers said.

`Remarkably Stable'

``These patients clearly do have quality survival added by the defibrillator,'' said lead researcher Daniel Mark, director of outcomes research at the Duke Medical Research Institute, in a telephone interview. ``Looking at people in different stages of the disease, there was no evidence toward any trend of people feeling worse. Generally speaking, their quality of life was remarkably stable.''

The $5 billion-a-year market for defibrillators is led by Medtronic, based in Minneapolis; Boston Scientific of Natick, Massachusetts; and St. Paul, Minnesota-based St. Jude Medical. The National Heart, Lung and Blood Institute, along with Medtronic, Wyeth and Knoll Pharmaceuticals, funded the studies.

``Patients like having this sort of insurance policy inside their chests,'' said David Steinhaus, medical director of the cardiac rhythm disease management unit at Medtronic, in a telephone interview. ``People are comfortable having an ICD and it doesn't reduce their quality of life over a long period of time.''

Improved Technology

The study began in 1997 and technology has improved dramatically since then, Steinhaus said. New devices deliver 70 percent fewer shocks, as some abnormal rhythms are corrected in a less draconian way, he said. The devices record heart rhythms, even when the patient feels nothing, and give doctors more information to use in their treatment plans, he said.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

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