NEW YORK, Dec 15 (Reuters Health) -- Implantable defibrillators -- devices
that shock the heart back into rhythm when it beats irregularly -- reduce the
chances of dying from sudden cardiac arrest, but drugs designed to prevent
irregular beats do not, according to the results of a landmark study.
"When we first started this study 10 years ago, we thought we'd show that
drugs would work to prevent sudden cardiac death in these high-risk patients. It
turns out we were wrong," said Dr. Eric Prystowsky, a study co-author from Beth
Israel Deaconess Medical Center in Boston, Massachusetts, in an interview with
Reuters Health.
In fact, heart disease patients treated with antiarrhythmia drugs (those
intended to prevent irregular heartbeats) fared no better than similar patients
who received no drug therapy at all, according to Dr. Alfred Buxton from Brown
University School of Medicine in Providence, Rhode Island and the other
investigators in the Multicenter Unsustained Tachycardia Trial (MUSTT). Their
report is published in the December 16th issue of The New England Journal of
Medicine.
On the other hand, patients who were treated with a surgically implanted
defibrillator were only one-fourth as likely to die from cardiac arrest or
irregular heartbeat than patients treated with antiarrhythmic drugs, the authors
report. Furthermore, their overall death rate from all causes was less than half
that seen in drug-treated patients.
All 704 patients who participated in this study underwent
electrophysiological (EP) testing, during which the cardiologist succeeded in
reproducing a dangerous irregular heart rhythm and identified which drugs could
prevent the irregular beats, the report indicates. Half the patients received
drug therapy, while half the patients received no drug therapy. Those patients
who continued to have irregular heartbeats on drug therapy could receive a
defibrillator.
The results clearly establish that patients with coronary artery disease
who have a weakened heart that occasionally beats irregularly and whose
irregular beats can be reproduced during EP testing can benefit from a
defibrillator, the investigators conclude.
"Patients like the ones in this study should have EP testing," said
Prystowsky, "and if their tests are positive, they ought to have a defibrillator
(surgically implanted). That approach offers them the best chances of survival."
"Studies haven't formally looked at whether every heart disease patient
should have EP testing," Prystowsky said, "so it's still an open question as to
how many patients could ultimately benefit from (a surgically implanted
defibrillator)."
