An important advance in preventing sudden death from a cardiac arrest is the implantable cardioverter-defibrillator, or ICD. Since its development, this technology may have saved the lives of thousands of individuals with severe cardiovascular disease.

Amazingly, a large number of young and middle-aged perfectly healthy individuals are inserting these devices in the hope of preventing death in the event they have a heart attack. Currently there is no evidence that inserting an ICD in normal people should ever be considered; potential side effects, including unnecessary shocks that cause damage to the heart muscle, make this sort of prophylactic therapy truly preposterous.

The ICD is best used for patients with severely weakened cardiac muscles or in those who have already been resuscitated from a cardiac arrest. For these patients, if cardiac arrest occurs, the ICD shocks the heart back into a normal rhythm. The ICD detects cardiac arrest due to a heart rate that is so fast that blood is no longer pumped out of the heart. This is referred to as a ventricular arrhythmia or tachycardia. Without the immediate shock to restore the blood pumping through the heart, unconsciousness occurs in seconds and death occurs within minutes. Ideally, the ICD acts as an immediate "first responder," preventing death and greatly improving the chance of recovery.

A weak heart is evaluated by measuring the heart's ejection fraction, which measures the percentage of blood pumped out of the heart with each beat. For a normal individual, the ejection fraction is about 70 percent. For those with severe heart failure, the ejection fraction can be 40 percent or less. Based on recent guidelines for insertion of an ICD, it is best used in patients who have an ejection fraction less than 35 percent but greater than 25 percent.

It is not surprising that physicians are implanting ICD devices when the potential benefits are not proven. Patients are generally told that they are at risk of having a cardiac arrest from a ventricular arrhythmia and that, if a ventricular arrhythmia occurs, an ICD will probably save their lives. However, it is just not that simple. In many cases, the ICD is implanted in patients over age 80 despite the fact that there is no evidence it will prolong life. It is also used when a patient's heart function is either not impaired enough or too severely damaged to warrant insertion of an ICD.

Despite the fact that a number of research studies have shown that implanting an ICD prolongs life and can prevent sudden death, a recent position paper published in the American Journal of Cardiology states that the benefits of ICD are overblown.

The researchers question whether patients are provided with sufficient information on the potential benefits and risks to make such a serious medical decision. Dr. Roderick Tung, the lead author of the article, states that the research studies done to date are fraught with problems making interpretation of the results difficult. Even in those patients in whom there is a clear indication for an ICD, the prolongation of life averaged no more than 2.6 months, more than 80 percent of patients who receive an ICD never benefit from it, and many receive unnecessary shocks either for no good reason or from a very short insignificant irregularity in the heart rate.

Unnecessary shocks can cause damage to the heart, can lead to further irregular heart rates, and are distressing enough to impair quality of life. And when death does occur, it is usually not from a sudden cardiac arrest but rather from an inexorable decline in heart function, leading to severe shortness of breath, a poor quality of life, and death associated with a great deal of suffering.

While the evidence is controversial, many experts maintain that for select patients the benefit of an ICD is substantial. However, everyone in the medical community understands that much more research must be done. If a cardiologist suggests that you need an ICD, make sure that you understand that this device is not without risks, the benefits are small, and its use must be limited to those patients in whom an indication is clear.

Dr. David Lipschitz is the author of the book "Breaking the Rules of Aging." To find out more about Dr. David Lipschitz and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com. More information is available at www.drdavidhealth.com.

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