March 29, 2004
Study shows implantable cardioverter defibrillators key to saving lives from sudden cardiac death
A study recently completed shows that people with heart failure live longer when they receive an implantable cardioverter defibrillator (IDC), a device offered by the Loma Linda International Heart Institute. The results from the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) were released on March 8. It included data from 2,521 patients enrolled in the largest ICD trial ever. The study showed that ICDs reduced death by 23 percent in people with moderate heart failure compared to those who did not receive defibrillators.
"This is a very important study because we now know that implanted defibrillators can save patients who have heart failure without coronary artery disease," says J. Thomas Heywood, MD, director of the Heart Failure Program at Loma Linda University Medical Center.
Implantable cardioverter defibrillators administer electrical shocks to stop ventricular fibrillation (VF)-a lethal condition in which the heart quivers chaotically and pumps little or no blood. They also stop ventricular tachycardia (VT), and less problematic arrhythmias. The shock from an ICD briefly shocks the heart and allows it to quickly resume a normal rhythm. They also collect information for the physician to use in programming the device to the exact needs of the patient. These devices are proven to be 98 percent effective in treating ventricular arrhythmias that can lead to sudden cardiac arrest.
Sudden cardiac arrest is the number one killer of Americans, taking the lives of nearly 450,000 people in the United States each year. An ICD can benefit those who have intermittent ventricular tachycardia, in which the heartbeat suddenly and without warning speeds up to dangerous levels, people who have survived a sudden cardiac arrest, and people who have survived a myocardial infarction (heart attack) and have impaired function in the lower chambers.
SCD-HeFT was a placebo-controlled, three-arm trial examining the use of ICD therapy and anti-arrhythmic drug therapy in patients who have moderate heart failure (New York Heart Association Class II or III), plus impaired pumping function of the left ventricle, the heart's main pumping chamber. One-third of patient enrolled in the study received an ICD provided by Medtronic. Another third received amiodarone, a medication used to manage fast heart rhythms, and one third received a placebo. All patients received optimal conventional heart failure medications when appropriated and tolerated, such as ACE inhibitors, beta-blockers, diuretics, statins, and aspirin. Sponsored by the National Heart Lung and Blood Institute of the NIH, with funding from Medtronic and Wyeth Pharmaceuticals, patient enrollment began in 1997 and continued through 2001.
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