15th BOSTON AF 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 and 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.)
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:
- increasing Vagal tone,
- 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 cannot 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.
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:
- Improves lesion effectiveness
- Reduces ineffective applications (by indicating insufficient contact force)
- Reduces collateral damage
- Improves safety
- Predicts sites of conduction recovery
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.
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 to 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 symptomsare 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.
|II.||Mild||Having a mild effect 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 affected 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.
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Last updated: Wednesday, September 2, 2015