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15th
BOSTON A-FIB SYMPOSIUM, January 14-16, 2010 "Atrial Fibrillation: Mechanisms and New
Directions in Therapy"
The annual
international Boston A-Fib Symposium is one of the most important conferences on
A-Fib in the world. It brings together researchers and doctors who share the
latest information. However, if you haven't read and
understood most of A-Fib.com, it may be difficult reading.
OVERVIEW-HIGHLIGHTS
The overall mood of
the 15th annual Boston A-Fib Symposium seemed to be a sense or feeling of
certainty in making progress and moving forward.
One might describe this Symposium's signature or most
prominent topic of interest as "New Achievements in A-Fib Imaging/Mapping."
4D & 5D IMAGING/MAPPING IN A-FIB
In a
thought provoking and somewhat controversial presentation, Dr. Douglas Packer
described new developments in A-Fib Imaging/Mapping as "4D and 5D Imaging."
Over the last few years, A-Fib doctors and medical companies
have developed very sophisticated Imaging/Mapping systems for doing A-Fib
ablations. For example, in the Satellite Case Transmission presented by
Massachusetts General, Dr. Moussa Mansour watched on a monitor a 3D rotating,
detailed color cartoon image of the patient's heart. He then pushed a button to
open up the end of the heart and look inside.
Rotational Angiography produces even more astounding images.
Instead of cartoon recreations, it shows the patient's actual heart in a 3D,
real time rotation. One can see the heart in every detail and can watch where
the ablation catheter is in the heart. (Seeing this for the first time takes
one's breath away.)
(The author is negotiating with different Imaging/Mapping
companies to make their images of the heart available on A-Fib.com.)
Time is the 4th A-Fib Dimension, according to Dr. Packer.
An example is the CardioFocus Endoscopic laser balloon Ablation System. The
doctor operating the CardioFocus catheter can directly see in color 3D real time
where the CardioFocus laser balloon is positioned in the heart. The operator
also sees tissue change imaging (A-Fib 4D), how the heart tissue is affected
over time as the Near Red Laser Light ablates in overlapping arcs around the
Pulmonary Vein opening. (This system is not yet approved by the FDA for use in
the US.)
The 5th A-Fib dimension would include other parameters
such as integrated temperature sensing imaging probes (and contact force
imaging---how much pressure an ablation catheter applies when ablating heart
tissue).
ATHLETES AND A-FIB
Athletes
and endurance training was the subject of two sessions and a great deal of
discussion. Dr. Stanley Nattel presented studies indicating that high level
physical training doubled the risk of developing A-Fib. In Dr. Nattel's animal
lab experiments, high level exercise training (30+ miles/week) developed A-Fib
by two mechanisms:
1. increasing Vagal tone,
2. producing structural remodeling of the heart---atrial
overload leads to atrial enlargement, increases atrial fibrosis and ventricular
hypertrophy.
Dr. Riccardo Cappato described how A-Fib hurts athletes'
performance and their ability to exercise. It also makes them ineligible for
competitions because they fail pre-qualifying tests (other professions and
avocations such as pilots have this same problem).
Because athletes often can not tolerate antiarrhythmic
drugs and/or refuse to take them, Dr. Cappato and other doctors in a panel
discussion say they recommend Pulmonary Vein Ablation as first line treatment
for athletes. A successful PV ablation restores athletes to full competition
intensity and makes them re-eligible to compete.
Current guidelines state
"catheter
ablation of A-Fib in general should not be considered as first line therapy."
At least one antiarrhythmic med should be tried first. But the guidelines also
state, "in
rare clinical situations, it may be appropriate to perform catheter ablation of
AF as first line therapy." Dr. Eric Prystowsky, who was instrumental in
writing the current A-Fib guidelines, stated that he uses PV Ablation as first
line therapy for athletes because of the above reasons.
ABLATION NOT A PERMANENT "CURE" FOR A-FIB
When counseling patients
with A-Fib, a successful A-Fib ablation is considered the only current hope of a
permanent "cure" for A-Fib (as compared to, for example, Rhythm or Rate control
drugs which tend to lose their effectiveness over time). But a study by Dr.
Francis Marchlinski cast doubt on this hypothesis.
He persuaded patients who had experienced successful PV
ablations and who were A-Fib symptom free, to be re-examined in the EP lab. He
found that some had Regrowth/Reconnection in their ablated vein openings even
though they were A-Fib symptom free. He also examined patients who had
Regrowth/Reconnection and reoccurrence of A-Fib after a successful PV ablation.
He estimated that there is a 5-6% chance of
Regrowth/Reconnection each year, out to five years. He doesn't have data for
beyond five years.
(The author has been A-Fib symptom free for 12 years.
Doctors he spoke to didn't think there was much chance of A-Fib reoccurrence
after 12 years.
However, the author will eliminate the work "cure" from
all A-Fib.com postings and instead use the term "A-Fib symptom free.")
CONTACT FORCE SENSING
A
Mini-Symposium was devoted to the subject of Contact Force Sensing.
When performing an ablation, doctors monitor power, duration,
and temperature; but not how hard the ablation catheter presses on heart tissue.
Insufficient ablation catheter contact can produce lesions that don't work or
that do not penetrate heart tissue, while too much contact or pressure can cause
perforation or damage to adjacent structures like the esophagus.
Dr. Karl-Heinz Kuck described a study using the TactiCath
contact force sensing system which found a high variability of force applied
both between different operators (which one would expect), and during an
ablation by one operator. 12% of ablation burns had a low force contact of under
five grams. (Perhaps this is one of the causes of re-occurrence of A-Fib
after ablation.) 82% of patients had a force of over 100 grams applied at
least once during their ablation. This could potentially cause steam pop,
puncture, and clotting. Dr. Hiroshi Nakagawa explained how Contact Force Sensing
catheters would eliminate the above problems.
Dr. Dipen Shah presented studies which showed that Contact
Force Sensing:
1. Improves lesion effectiveness
2. Reduces ineffective applications
(by indicating insufficient contact force)
3. Reduces collateral damage
4. Improves safety
5. Predicts sites of conduction
recovery
STROKE PREVENTION
A Mini
Symposium was held on Stroke Prevention in A-Fib.
Dr. David Singer described why A-Fib is a major risk factor
for stroke. Because in A-FIb the left atrium doesn't contract to push blood into
the ventricle, clots can easily form especially in the Left Atrial Appendage.
Warfarin (Coumadin) reduces the risk of stroke by 68% and is
safe at the proper levels. Warfarin's risk of producing an hemorrhagic stroke is
only 0.3%/year compared to a normal risk of 0.1%/year. But warfarin is
underused. 40% of people who should be on warfarin don't take it, perhaps
because of its side effects, bleeding risk, and the difficulty in maintaining
proper INR levels.
Aspirin is much less effective, only reducing the risk of
stroke by approximately 21%. Clopidogrel, when taken with aspirin, reduces the
risk of stroke by approximately 28%. But it significantly increases the risk of
major hemorrhage, mostly gastrointestinal.
The good news, both for patients and doctors, is stroke rates
in A-Fib are declining.
DABIGATRON
TO REPLACE WARFARIN?
The RE-LY
study found that dabigatron reduces the risk of stroke by 30% while also
reducing the risk of intracranial bleeding by 30% (dabigatron dose 150 mg). It
also reduces vascular death. Unlike warfarin which needs four days loading to be
effective, dabigatron works right away. It doesn't have to be monitored for INR
levels. (Both doctors and patients are impatiently waiting for FDA approval
for dabigatron, which hopefully will come soon.)
THE WATCHMAN DEVICE TO PREVENT
STROKE
The
Watchman Device works by closing off the Left Atrial Appendage where 90% of
clots/strokes come from. (See
The Watchman Device.)
Dr. Zoltan Turi showed a slide of a man who had a Watchman
Device installed, but died nine months later from other causes. His family
graciously allowed doctors to do an autopsy to examine how the Watchman device
had worked. The Watchman Device was covered over by smooth heart muscle tissue
which looked like any other part of the heart. (The Editor is negotiating to
get a copy of this slide for A-Fib.com.)
Data from the
Watchman
Device study showed that it is safe, effective and easily installed (one
doctor said he installed them in 20 minutes). A surgeon speaking at the
Symposium said he had to remove Watchman Devices (implying that this is a major
problem with the Watchman Device). Acknowledging there was a short learning
curve when first installing
the
Watchman Device, Dr. Turi
said that to date only four have had to be removed.
An FDA
preliminary panel has approved the Watchman Device. But the vote was
close---7-5. All agreed that the Watchman Device worked, but some wanted to see
more than 800 cases. Clinical trials of the Watchman Device have been extended.
FDA AT THE BOSTON A-FIB
SYMPOSIUM
Dr.
Randall Brockman and Dr. Jun Dong from the FDA both expressed the FDA's
willingness to help and encourage the development of effective therapies for
A-Fib. Dr. Brockman pointed out that A-Fib is a major public health issue (some
have called it an epidemic). He also expressed the FDA's interest in developing
an A-Fib Registry (SAFARI). (He was asked why new devices or drugs seem to be
always started in Europe.)
Dr. Dong explained the FDA's Investigational Device Exemption
(IDE) and how it could be used by both industry and physicians. He welcomed
physician-initiated trials and gave the audience his email address and office
phone number.
MEASURING QUALITY OF LIFE IN
A-FIB
Having
A-Fib can be devastating. A-Fib can affect General and Mental Health, as well as
Physical and Social Function.
Some A-Fib symptoms can be described and objectively
quantified by degree and severity: Palpitations, Dyspnea (difficulty breathing),
Chest Pressure and Pain, Dizziness, Presyncope, Syncope (fainting), Exercise
Intolerance and Fatigue.
Other symptoms
are more subjective: such
as Anxiety and Depression.
"Quality of Life" is a subjective phenomenon based on each
person's perception, experience, beliefs, and expectations. What may be
intolerable for one person may not be all that bad for another. Dr. Jeremy
Ruskin is proposing an A-Fib Symptom Classification System that also includes
Quality of Life. Such a system or universally accepted shorthand would
facilitate communication between doctors and patients, and between health care
providers.
CLASS
SYMPTOM SEVERITY
I.
Asymptomatic
II. Mild---having
a mild affect on a patient's qualify of life, mild awareness
of symptoms in Persistent/Permanent A-Fib, rare episodes (less than a
few a year) in Paroxysmal A-Fib
III.
Moderate---having a moderate affect
on quality of life,
moderate
awareness of symptoms on most days in Persistent/Permanent A-Fib,
more common episodes (more than every few months) and/or more
severe symptoms in Paroxysmal A-Fib.
IV. Severe---having
a severe effect on quality of life, very unpleasant
symptoms in Persistent/Permanent A-Fib, frequent and highly
symptomatic episodes in Paroxysmal A-Fib
Syncope (fainting)
Congestive Heart Failure because of A-Fib
DR. JEREMY RUSKIN HONORED
Dr. Jeremy Ruskin from
Massachusetts General Hospital was honored for his 15 years of organizing the
Boston A-Fib Symposium. He was given a
Chelsea clock from Boston
and was enthusiastically applauded for his years of service to the A-Fib
community.
(More to follow)