ICDs Cut Deaths by 20%

Aug. 20, 2007 -- ICDs in patients with heart failure cut death rates by 20%. But most patients never actually get a therapeutic jolt from their heart-shock implants, a new report finds.

Implantable cardioverter defibrillators -- ICDs -- are lifesavers for people at high risk of sudden cardiac death. But the sophisticated devices aren't without risk. Is the benefit really worth it?

Yes, find Justin A. Ezekowitz, MB, BCh, and colleagues at the University of Edmonton, Alberta, Canada. The researchers analyzed data from all major clinical trials and observational studies of ICDs.

Having heart failure can put you at risk for a dangerous abnormal heart rhythm. An ICD monitors the heart rhythm and shocks the heart when necessary to get it back to a safe rhyth m.

The bottom line: For a person with heart failure getting an ICD, the device cuts the overall risk of death by 20%.

However, no more than one in three patients with an ICD ever gets a therapeutic shock from the device. This, Ezekowitz and colleagues note, means that researchers must do a better job of identifying patients who truly benefit from getting the implant.

The reason is that getting an ICD carries some risks:

• Just over one in 100 patients dies during ICD implant surgery.
• For every 100 years of use, clinical trials suggest, ICDs give 19 inappropriate shocks. Such shocks may increase, rather than decrease, a patient's risk of death.
• Complications can occur after implantation, such as infection at the implantation site and device malfunction.

"Most patients currently implanted with an ICD never receive a therapeutic discharge but are exposed to the risks of ICDs outlined in our report," Ezekowitz and colleagues observe.

The researchers report their findings in the Aug. 21 issue of Annals of Internal Medicine.