Irregular Heartbeats, Sudden Death Shocked by Device
Feb. 9, 2000 (Indianapolis) -- A genetic disease that causes the walls of
the heart to become enlarged, called hypertrophic cardiomyopathy (HC), has been
associated with a risk of sudden death due to unhealthy heart rhythms, called
Using medications to prevent arrhythmias is limited by a lack of evidence
about their effectiveness and the side effects of long-term use. Results of a
study on the use of implantable cardioverter-defibrillators (ICDs), reported in
the Feb. 10 edition of The New England Journal of Medicine, suggests the
devices can play an important role in preventing sudden death in these
patients. ICDs are essentially a smaller, automatic version of the
defibrillator that is used in ambulances and emergency rooms to "shock"
"Until now, there had never been a large series of patients with this
disease who were studied to see if an ICD could sense and terminate potentially
lethal heart rhythms," says Barry J. Maron, MD, director of cardiovascular
research at the Minneapolis Heart Institute Foundation, in an interview with
WebMD. "If it could, we also wanted to know if it would be life-saving in a
significant number of persons."
One hundred twenty-eight patients were enrolled in the trial at 19 centers
in the U.S. and Italy. ICDs were implanted in the chests of patients ranging
from 8 to 82 years old. The researchers followed them for about three years and
kept track of how often the defibrillator fired and whether it did so
They found that the ICD had identified an arrhythmia and shocked the heart
back into a normal rhythm in almost 25% of the patients.
However, "a patient with HC should not assume they are automatically a
candidate for an ICD," says Maron. "It is not a treatment for the
disease itself and should only be given to those who are at high risk for
sudden death. In addition, ICD is not without adverse consequences of its own
such as inappropriate discharges and infection."
David P. Rardon, MD, clinical electrophysiologist with the Indiana Heart
Institute in Indianapolis, agrees.
"Even based on this article, whether a patient should have a
defibrillator is not an easy question to answer," he says. "There are
some patients whose risk of dying from HC is small. The hardest part today is
deciding where a patient fits."
"I think that the study shows those with certain symptoms and risk
factors should have an ICD," Randy A. Lieberman, MD, director of
electrophysiology at Wayne State University/Detroit Medical Center, tells
WebMD. "However, this group did not address whether those who are [have no
symptoms] should also be treated. Another study would be needed before we can
answer the questions of this group."
- People with hypertrophic cardiomyopathy have enlarged hearts and often are
at risk of dying from an unhealthy heart rhythm, called arrhythmia.
- During a study, doctors found an implanted electronic device, called a
defibrillator, detected and stopped potentially harmful arrhythmias with a
shock to the heart in almost 25% of patients.
- Observers note that doctors still have to determine which patients with
this type of heart disease would do well with this therapy.