Implantable Defibrillators:  Magnitude of Benefit Questioned   By Paula Rasich Reviewed by Elizabeth Klodas, MD, FACC September 30, 2008--Each year, thousands of people with heart disease get implantable cardioverter defibrillators (ICDs), small devices which can shock a potentially deadly heart rhythm back to normal.

Over the past decade ICDs have become much more widely used to reduce the risk of sudden cardiac death in heart failure patients, heart attack survivors and others who are at increased risk for fatal arrhythmias.  Although these devices are life-saving, they can be associated with complications and are extremely expensive, making it critical that, for patients who receive them, benefit clearly outweighs risk. 

After reviewing 12 major defibrillator trials going back 10 years, and weighing the risks against the benefits, Roderick Tung, MD, a clinical instructor of electrophysiology at UCLA in Los Angeles and colleagues came to the conclusion that the benefits of ICD therapy may have been overestimated.

Defibrillator therapy has been used as a kind of safety net to protect against sudden cardiac death, but doctors now have other options. “Medical therapy [beta blockers and ACE inhibitors] that we use today is much better and has been shown to prevent mortality in patients after [heart attack] and heart failure,” says Dr. Tung. “Patients in the landmark clinical trials several years ago did not always receive these medications and therefore, the true magnitude of benefit from defibrillator therapy was likely overestimated.”

In this review, researchers point to evidence showing that implantable defibrillators have a downside. For instance, they can send shocks when you don’t need them (in up to 25% of patients), increasing the risk of anxiety and depression.

In addition, the devices are placed under the skin just below the collarbone and a thin wire (lead) connects the generator to the heart. Sometimes the lead breaks and needs to be replaced. In one study, 15% of leads failed during a 13-year follow up period.  And although rare, the possibility of device malfunction exists.

There is additional concern that implanted heart devices can cause infections and other side effects. In another study, patients randomized to receive ICD therapy had a higher incidence of death from non-arrhythmic causes.

“A defibrillator does provide a safety net, but you also have to accept all the up front complications of surgery and potential quality of life issues,” says Dr. Tung. “Up to 80% of patients receiving a defibrillator will never have it go off, but they still incur all the risks associated with the device.”

This study is published in the September 30, 2008 issue of the Journal of the American College of Cardiology.

Editor’s comment:  The findings of this study do not indicate that ICDs should not be used.  Rather, the authors point out that the benefits of ICD implantation may not be as high as previously thought.  Fatal rhythm abnormalities remain a real risk in certain patients with heart disease, and all patients who are being considered for ICD implantation should discuss the pros and cons of various treatment options with their cardiologists.

Sources:

Tung R et al. A Critical Appraisal of Implantable Cardioverter-Defibrillator Therapy for the Prevention of Sudden Cardiac Death. Journal of the American College of Cardiology, 2008. 

Roderick Tung, MD, Clinical Instructor of Electrophysiology at UCLA, Los Angeles, California.