Implantable Defibrillators Reduce Death by 23%
01/28/05 Portland, Ore.
Results offer new hope to patients at risk of cardiac arrest, according to study in The New England Journal of Medicine
Implantable cardioverter-defibrillators (ICDs) reduce sudden death by 23 percent in people with congestive heart failure, according to a study appearing in the Jan. 20 issue of The New England Journal of Medicine. Oregon Health & Science University was one of 150 medical centers participating in the nationwide study and the only study site in Oregon.
"By participating in this clinical trial, OHSU provided dozens of heart failure patients with access to ICD technology at little or no cost. Simultaneously, we raised the standard of health care in the state by perfecting our own clinical expertise," said Ray Hershberger, M.D., director of OHSU's heart failure and cardiac transplant program and professor of medicine (cardiology) in the OHSU School of Medicine.
The study also showed that amiodarone, a common anti-arrhythmia drug once considered a gold-standard treatment to prevent sudden cardiac death, has no favorable effect on survival.
"Amiodarone is clearly ineffective for preventing sudden death in heart failure patients," said Hershberger. "For some patients and doctors, this may come as surprising news because the drug is still in common use."
Heart failure is a progressive condition that limits the lower chambers of the heart from pumping sufficient blood to meet the needs of the circulatory system. This causes symptoms such as fatigue, shortness of breath, water retention (edema) and heart rhythm irregularities. Currently, about 3 million people in the United States have this affliction.
While heart failure is a serious disease, thousands of these people live well with the condition. However, some patients are at risk of sudden death from arrhythmia (rapid heart rate) due to the severity of their disease. For patients and physicians alike, this situation is particularly vexing because no one understands what will trigger a life-threatening event. Sudden cardiac arrest (SCA) kills approximately 250,000 people each year in the United States and an estimated 95 percent of those die before reaching a hospital.
"These patients already have a decreased cardiac output and when an arrhythmia occurs, it can quickly snowball," said Deirdre Nauman, R.N., senior research associate at the OHSU Heart Research Center. "Literally, a patient will seem fine one day and the next day an arrhythmia occurs. Death usually results within minutes."
The Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) compared the lifesaving benefits of ICDs, amiodarone and a placebo in 2,521 patients with moderate heart failure and poor heart pumping function who had not experienced a prior episode of sudden cardiac arrest. Over the course of the study (the median time was 45.5 months), a total of 666 patients died: 244 deaths (29 percent) in the placebo group, 240 deaths (28 percent) amiodarone group but only 182 deaths (22 percent) in the group undergoing ICD therapy. The National Heart Lung and Blood Institute of the National Institutes of Health (NIH) sponsored the study.
An ICD is surgically implanted beneath the skin in the upper chest. When a patient?s heart rhythm accelerates, the device delivers an electrical current to stop the otherwise deadly rapid and chaotic heartbeat. Approved for use since the late 1980s, ICDs have been prescribed primarily for the 5 percent of people who had already survived an episode of sudden cardiac arrest. This study indicates this clinical option should be considered for the many patients who have advanced heart failure but no specific history of cardiac arrest.
While not every heart failure patient is a candidate for an ICD, the study indicates that most heart failure patients should be evaluated for the procedure after first receiving optimal conventional medical therapy, such as ace inhibitors and beta blockers, said Hershberger.
"Heart failure is a chronically undertreated condition," said Hershberger. "Nearly half of this patient population is not seeking out or receiving proper care."