March 19, 2002 -- It's tragic. A friend or loved one dies suddenly, unexpectedly. We might hear that he or she died of a "massive heart attack." But most commonly, this is not the case.
The common cause of sudden cardiac death, or SCD, is an abnormal heart rhythm called ventricular tachycardia or ventricular fibrillation. This rapid rhythm originates from areas of scarring in the lower chamber of the heart.
During an attack, the heart is unable to pump efficiently. The blood pressure falls. If a normal rhythm is not restored within four to six minutes, the patient may die.
Prompt initiation of CPR can save lives but, sadly, in most communities, only one in 10 victims of SCD ultimately survives.
A high-tech device called an implantable cardioverter-defibrillator, or ICD, has been proven to save lives in selected groups of patients.
This small, battery-powered device is implanted under the skin and connects to a wire threaded through the veins down into the heart. It waits silently, watching the heart rhythm every moment of every day.
If SCD strikes, the device leaps into action, delivering a lifesaving electrical shock directly to the heart. It restores a normal heart rhythm and saves the patient's life.
Evidence of Benefit
Studies have shown the benefit of ICD insertion in high risk patients. In particular, patients who have survived a cardiac arrest or have had short or long bursts of rapid ventricular tachycardia have an improved outcome if ICDs are implanted.
But these patients only account for a small percentage of the estimated 400,000 sudden deaths each year. There must be a better way to identify patients before their cardiac arrest so that this outcome can be avoided.
Investigators of the Multicenter Automatic Defibrillator Implantation Trial, or MADIT, considered that testing the amount of blood that the heart pumps, also known as the ejection fraction, could determine a future SCD.
A normal heart pumps out about 60 percent of its volume with each beat. But after one or more heart attacks, heart muscle is lost and the volume of blood the heart pumps out decreases.
A reduction of this measurement is a known factor predicting decreased long-term survival after a heart attack.
The MADIT II study identified patients with an ejection fraction equal to or below 30 percent. Part of the group received ICDs as preventative treatment and part of the group received no device.
Everyone was treated with other medicines known to improve symptoms and survival after a heart attack. They determined that ICDs decreased the risk of dying by 31 percent.
ICD technology is here and available. Most hospitals in this country have arrhythmia specialists who are trained in the implantation of ICDs.
The ejection fraction is a common test that is performed in everyone who has suffered a heart attack. Based upon the results of the MADIT II trial, physicians can start saving lives today by implanting ICDs in this new group of patients. It seems like everyone is a winner.
Unfortunately, saving lives costs money. Each defibrillator system costs $25,000 to $30,000. Every five to eight years, the battery wears out and a new device needs to be implanted. The MADIT II trial treated 16 patients with defibrillators in order to save one person's life.
With an estimated 600,000 patients who meet the description of patients studied in the MADIT II trial, can we as a society afford this therapy? Clearly the challenge now is not medical, but rather deciding how we choose to spend our health-care dollars.
Ask any patient whose ICD has saved their life. The answer will be very clear.
Dr. David E. Haines is a professor of internal medicine and co-director of cardiac electrophysiology at the University of Virginia Health System.