Good news on atrial fibrillation
In May, 2001, at the North America Pacing and Electrophysiology Society (NASPE) Scientific Sessions in Boston, several investigators reported on advances in the treatment of the most stubborn of arrhythmias atrial fibrillation. (Click here for a quick review of atrial fibrillation.)
Expected increase in atrial fibrillation much higher than previously
Data were reported from the AnTicoagulation and Risk
Factors in Atrial Fibrillation (ATRIA) study, suggesting that the number of
people who will develop atrial fibrillation over the next several decades is
much higher than previously thought.
The study examined a large database from Kaiser Permanente
of Northern California that includes almost 2 million individuals.
They found that the prevalence of atrial fibrillation among that
population is nearly 1%. Further, the prevalence of atrial fibrillation increases
dramatically with age, such that only 1 in 1000 people under age 55 has atrial
fibrillation, but nearly 1 of 10 over the age of 80 has the arrhythmia.
Given the rapid aging of the population over the next 40 years, the
incidence of atrial fibrillation (based on these data) is likely to be 2 ½
times as high as previously thought. It
is now predicted that 5.6 million Americans will have atrial fibrillation by
Why is this important, and why is it good?
This startling prediction is important because it indicates that the
public health burden due to atrial fibrillation over the next few decades will
be much higher than has been thought.
It is good, because companies trying to develop
effective therapy for this difficult-to-treat arrhythmia will see a even bigger
pot of gold at the end of the rainbow. We
can expect the biomedical industry to redouble their efforts to find safe and
effective treatments. This new
impetus will guarantee that many more research dollars will be poured into the
effort to find an answer to atrial fibrillation.
Dual-site atrial pacing helps prevent recurrence of atrial fibrillation
For several years, investigators have postulated that a
pacemaker that paces the atria from two locations instead of one (which is the
standard) may help prevent recurrences of atrial fibrillation.
A multi-center trial called Dual Site Atrial Pacing for Prevention of
Atrial Fibrillation (DAPPAF) was designed to test this hypothesis. (Click here
for a quick review of pacemakers.)
Data from DAPPAF presented at the NASPE meetings show that
dual-site atrial pacing significantly reduced the number of episodes of atrial
fibrillation. Dual-site pacing also
resulted in more efficient atrial function, as measured by echocardiography.
Dual-site atrial pacing requires placing two atrial leads
instead of one, and dual-site atrial pacemakers are not generally available at
present. However, based on the data
reported from the DAPPAF study, it is likely that manufacturers will begin
including the capacity to perform dual-site atrial pacing in future pacemakers.
Dynamic Atrial Overdrive pacing reduces atrial fibrillation
In a study sponsored by St. Jude Medical, Inc., a new
pacing algorithm (a "pacing algorithm" is the software scheme used to
determine the timing of pacing) called Dynamic Atrial Overdrive (DAO)
reduced the number of episodes of atrial fibrillation.
The DAO scheme is designed to maintain more-or-less
uninterrupted atrial pacing, while maintaining an optimal heart rate.
DAO monitors the patients own atrial rate, and paces just slightly
faster than that intrinsic heart rate.
Investigators reported a significant decrease in the
incidence of atrial fibrillation when DAO pacing was used, and patients reported
a significant improvement in social functioning with DAO pacing.
4) Catheter ablation of atrial fibrillation moves another step forward
Atrial fibrillation has proven relatively resistant to being cured by radiofrequency ablation. This is because in atrial fibrillation - in distinction to many other arrhythmias - there is generally not a small, localized area within the heart that, if ablated, will result in a cure of the arrhythmia.
During the 1990s it was learned that atrial fibrillation can be stopped by creating a series of linear surgical scars in the atrial muscle, in an open heart operation called the Maze procedure. Since then, the Holy Grail of atrial fibrillation has been to figure out how to duplicate the effects of the Maze procedure without needing to do a major surgical operation, using radiofrequency catheter ablation. Several techniques have been tried, with only spotty success.
At the NASPE sessions, Dr. Neal Kay from the University of Alabama, Birmingham, reported on a new approach to the catheter ablation of atrial fibrillation. Dr. Kays group found that by creating four linear catheter lesions in the atria, combined with lesions to encircle the openings of the pulmonary veins in the left atrium, they were able to control atrial fibrillation in 13 of 16 patients. This result is preliminary, and the patients still require antiarrhythmic medication (which were not effective prior to the ablation procedure,) but Dr. Kays results represent an extremely promising step in the quest to find a reproducible method for ablating atrial fibrillation. It is likely that within a few years, techniques based on the work of Dr. Kay and his group lead to a much more effective and much more reliable method for ablating atrial fibrillation.
The Bottom LineAtrial fibrillation remains difficult to treat in many cases. However, the medical-industrial complex sees a huge payoff to the company that comes up with a widely-applicable, safe and effective treatment for this arrhythmia, and work is proceeding rapidly on many fronts. At virtually every cardiology meeting, the results of some of these efforts are reported. Studies presented at the recent NASPE meeting indicate that newer pacing techniques may soon become a standard method of reducing the number of episodes of atrial fibrillation in patients who have this arrhythmia and who also need permanent pacemakers. And for the first time, clear and tangible progress is being made toward a radiofrequency ablation "cure" for atrial fibrillation. The new information reported here reflects only some of the avenues that are being explored in the treatment of this difficult arrhythmia. Within just a few years, several new therapeutic options will be widely available for patients with atrial fibrillation.
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