Studies Examine Effectiveness of Implantable Defibrillators

Found effective to prevent death after heart failure, not effective after a heart attack

TUESDAY, Nov. 17 (HealthDay News) -- Implantable cardioverter-defibrillators (ICDs) are effective in preventing death after heart failure, but are not effective in preventing death early after a heart attack, according to two reviews in the Nov. 24 issue of the Journal of the American College of Cardiology.

In the first review, Joseph D. Mishkin, M.D., from the University of Florida College of Medicine in Gainesville, and colleagues note that ICDs are now the standard of care for the prevention of sudden cardiac death in patients with heart failure. However, both appropriate and inappropriate shocks increase the risk of death, particularly from heart failure.

In the second review, Jeffrey J. Goldberger, M.D., and Rod Passman, M.D., from Northwestern University in Chicago, note that ICDs have not been shown to reduce the risk of sudden death after myocardial infarction (MI) even when implanted early into high-risk patients. Death does not appear to be due to arrhythmia alone, since ICDs are known to be effective in terminating arrhythmias.

"The etiology of this acute MI-sudden cardiac death paradox is unclear, but may be related to the changing nature of the substrate over the several month period after acute MI," Goldberger and Passman conclude. "Further investigation is needed to delineate the actual causes of death in the early post-MI period and which interventions can be implemented to reduce the increased rate of sudden death that is observed."

Authors on both studies reported consulting and financial relationships with pharmaceutical and medical device companies.

Abstract - Mishkin
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Abstract - Goldberger
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