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By Melissa Tennen, HealthAtoZ writer
A device that regulates heart rhythms called an implantable cardiac defibrillator (ICD) significantly reduces the risk of death for people living with heart failure, according to a major study from the National Heart, Lung, and Blood Institute (NHLBI).
The study also showed the implant worked far better than a standard treatment for abnormal rhythms, a drug called amiodarone.
"There is a high incidence of sudden death in people with heart failure and this study shows it can be reduced with the right therapy - the ICD," says Michael E. Cain, M.D., president of the Heart Rhythm Society and director of the cardiovascular division at Washington University School of Medicine in St. Louis. He did not take part in the study. "It's pretty conclusive. In the year 2004, if you have a damaged heart, this is the best thing you can do to reduce the risk of death."
This finding from a federal study called Sudden Cardiac Death in Heart Failure (SCD-HeFT) helps doctors decide how to treat heart failure, which is a chronic and progressive disease. Heart failure means your heart either cannot pump enough blood or pump with enough force for your whole body. Heart failure, which may last for years, can be caused by coronary artery disease, heart attack, high blood pressure, a viral infection or diabetes.
Other studies have shown similar benefits, although this particular research lasted longer. Also, this report is one of the first to show ICDs can help reduce the risk of death for people with heart failure caused by something other than a heart attack.
Device restores rhythm
About 50 percent of people with heart failure who die had what doctors call a sudden cardiac death (SCD), probably from ventricular tachyarrhythmia - rapid heartbeats in the lower part of the heart. SCD means the heart stops and the brain is deprived of oxygen, causing death within minutes. Once started in an abnormal rhythm, the heart cannot recover on its own, which is why ICDs can be lifesavers. They send electric shocks to the heart to help return it to its normal rhythm. SCD is not a heart attack, which is caused by a blockage in the arteries.
About the size of a pager, the ICD is inserted by the doctor under the skin below your collarbone.
The study involved 2,500 people divided into three groups. One group got a placebo, or sugar pill. The second was treated with the antiarrhythmic drug amiodarone. Antiarrhythmic drugs help prevent irregular heartbeats. The third group received ICDs.
Researchers followed the participants for nearly four years. When they enrolled, people in the study had moderate to severe heart failure and were ages 19 to 90 with 77 percent men and 23 percent women.
"The take-home message is this: If you have symptomatic heart failure and your ejection fraction is less than 30 percent, then your survival may be improved with an ICD," says Michael Domanski, M.D., a cardiologist with NHLBI.
Ejection fraction is how much blood is pumped from the heart chamber. Healthy hearts have 50 to 75 percent.
Possible side effects
ICDs can have serious complications, including inflammation of the pericardium, the sac that surrounds the heart; heart attack; congestive heart failure; and post-operative stroke. Serious infections can develop in the area around the device.
Sudden cardiac death is the leading cause of death in the United States, about 300,000 each year. Heart failure affects 5 million Americans.
Here's how you can stay heart healthy.
- Watch your salt intake. Salt causes fluid to build up in the body.
- Get moving. Exercise helps ward off heart disease and diabetes. Talk to your doctor before you start any exercise program.
- If you are overweight, lose weight.
- Eat a low-fat, fiber-rich diet loaded with fruits and vegetables.
- Don't smoke.
- Check your cholesterol, blood pressure and blood sugar levels.
- Get enough sleep.
This article was reviewed and updated June 2007.
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