2013 BOSTON ATRIAL FIBRILLATION SYMPOSIUM

Presentations Highlights

by Steve S. Ryan, PhD

Over the three days of the 2013 BAFS, there were 43 presentations, eight Live and Pre-Recorded Case Presentations, and two 2-hour-long panel discussions. The following are my brief summaries of 16 presentations. For my longer articles, see Steve’s In-depth Reports.

List of my highlight reports:

•  Renal Denervation, Dr. Vivek Reddy
• “Difficult Cases in AF Management”
• Lariat II Live Demo, Dr. Moussa Mansour
• Shapes of LAA & Risk of Stroke, Dr. Dhanunjaya Lakkireddy, Dr. Andrea Natale
• Jet Ventilations, Dr. Francis Marchlinski
• Evolution of PVI Guidelines—PVI Now First Line Therapy, Dr. Jeremy Ruskin
• New CryoBalloon Catheter, Dr. Douglas Packer
• A-Fib Produces Fibrosis? Dr. Hans Kottkamp
• Ablation Using Low-Voltage Electrograms, Dr. David Wilber
• Claim that PV Isolation Not Necessary, Dr. Sanjiv Narayan
• Cox Maze IV 1% Complication Rate, Dr. Ralph Damiano, Jr.,
• FDA Discusses “Reduced A-Fib Burden” as Primary End Point, Dr. Jun Dong and Dr. Judith Davis
• Animal Experimental Studies, Dr. Davis
• New Irrigated Tip RF Circular Catheter, Dr. Pierre Jais
• ‘Reverse Remodeling’ Ablation—Medical Breakthrough!, Dr. Pierre Jais
• CryoBalloon Ablation, Dr. Douglas Packer from the Mayo Clinic
• Focus on Stenosis (Inflammation and scarring or occlusion of the PV Opening after Ablation), Dr. Douglas Packer

Renal Denervation

Another notable innovation was Dr. Vivek Reddy’s pre-recorded case presentation on “renal denervation.” It was fascinating to watch as Dr. Reddy threaded a catheter up and across arteries to ablate nerves leading to the kidneys. See “Live Satellite and Pre-Recorded Case Presentations” below. The next day Dr. Reddy gave a talk on Renal Denervation. As many as 30% of people with high blood pressure have uncontrollable hypertension where meds, lifestyle changes, better diet, etc. have no effect. And hypertension accounts for around 1/2 of all A-Fib cases. Renal Denervation (applying RF pulses to the nerves in the vascular wall of the arteries leading to the kidneys) both lowers uncontrolled high blood pressure and reduces A-Fib.

As always at the Symposium, there were some controversial presentations “Is PV Isolation Necessary for Successful Ablation?” and “A-Fib doesn’t produce fibrosis.”

Difficult Cases
The “Difficult Cases in AF Management” session produced an insightful, hotly discussed case which the author repeats nearly in its entirety. A young athlete of 14 developed A-Fib. How does one treat A-Fib in someone so young (the youngest the author has ever heard of)? Opinions were definitely mixed.  See “Difficult Cases in AF Management” below.

Lariat II Live Demo
The satellite and pre-recorded case presentations were wonderful, sometimes jaw-dropping, and worth the price of admission by themselves. Dr. Moussa Mansour demonstrated live how to insert a Lariat II noose-like device over the Left Atrial Appendage (LAA) using a balloon inside the heart to expand the LAA. He then used catheters with magnets inserted from both outside the heart and inside the heart to guide the Lariat II noose over the LAA and tighten it, thereby closing off the LAA and eliminating most threats of an A-Fib stroke.See “Live Satellite and Pre-Recorded Case Presentations” below.

Shapes of LAA & Risk of Stroke
Speaking of the LAA, Dr. Dhanunjaya Lakkireddy described how the LAA can have very different shapes and structure. The shape of one’s LAA may have something to do with the risk of A-Fib stroke. 48% of A-Fib patients have a “Chicken Wing” structure which has less risk of stroke. The other shapes “Cactus”, “Windsock”, and “Cauliflower” carry more risk of stroke.

In another pre-recorded case Dr. Andrea Natale worked on the most difficult case A-Fib doctors usually encounter—an older man in persistent A-Fib and with significant scarring (fibrosis). One technique he showed was ablating around the Left Atrial Appendage which he said was often the key to a successful ablation.

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Jet Ventilation
In the pre-corded case presentations, Dr. Francis Marchlinski demonstrated the use of “Jet Ventilation” during an ablation. Jet Ventilation slows down the heart so that it’s easier to make an ablation.

Evolution of PVI Guidelines—PVI Now First Line Therapy
Dr. Jeremy Ruskin gave a historical perspective on how amazingly fast catheter ablation (Pulmonary Vein Isolation, PVI) has been accepted and gone into widespread use as therapy to make patients A-Fib free. Back in 2001 PVI was barely an afterthought in medical guidelines, while today it’s recognized as first line therapy. See “Amazing Evolution of Catheter Ablation Guidelines” below.

New CryoBalloon Catheter
Dr. Douglas Packer in another pre-recorded case demonstrated the use of the new CryoBalloon catheter with eight jets rather than four to produce better freezing.

A-Fib Produces Fibrosis?
Dr. Hans Kottkamp presented data from his center and others which he said indicated that A-Fib doesn’t always produce fibrosis. But the second speaker after him, Dr. Jose Jalife, showed an experimental study using sheep hearts where inducing A-Fib clearly increased or was associated with an increase in fibrosis. Even the experts don’t always agree. The author has to admit that the scientific sessions on Thursday morning aren’t always the easiest to follow. But Dr. Jalife’s experiments seemed very well designed and conclusive.

Ablation Using Low-Voltage Electrograms
Dr. David Wilber, in a pre-recorded case, showed how he ablated someone who had failed both an ablation and a Thorascopic Maze operation. He primarily used low voltage electrograms.

Claim that PV Isolation Not Necessary
Dr. Sanjiv Narayan, inventor of the FIRM mapping and ablation system, gave one of the most controversial presentations entitled “Is PV Isolation Necessary for Successful Ablation of PAF (Paroxysmal A-Fib Ablation).” If there is one constant among the thousands of EPs doing catheter ablation for A-Fib, nearly all start with ablating the Pulmonary Vein openings (PVs). No one seemed to accept Dr. Narayan’s position. It was like throwing raw meat to a pack of hungry lions (I’m exaggerating here). In the following discussion everyone piled on poor Dr. Narayan. He himself admitted in the discussion session that when he didn’t isolate the PVs, they were still firing A-Fib signals into the heart, though these signals seemed to decrease over time. For a further discussion of the FIRM system, see my 2012 article: ‘FIRM’ (Focal Impulse and Rotor Modulation) for Catheter Ablation of A-Fib by Dr. Narayan of UC San Diego (will open in new browser window).

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Cox Maze IV 1% Complication Rate
Dr. Ralph Damiano, Jr., in the 2 1/2 hour session on Persistent A-Fib, described the evolution of the original Cox Maze operation to today’s Cox Maze IV which now makes a box lesion set of 13 lesions, According to Dr. Damiano, it’s something of a misnomer to call this operation a “Maze”. The big news for patients is the complication rate of the Cox Maze IV has dropped from 11% to 1%. This is a much lower complication rate than most surgical approaches where the “major adverse event” rate approaches 25%. (See Surgical Versus Catheter Ablation―Flawed Study, But Important Results for Patients)

FDA Discusses “Reduced A-Fib Burden” as Primary End Point
The FDA again participated in the Symposium this time bringing two members, Dr. Jun Dong and Dr. Judith Davis. This attendee was surprised when Dr. Dong talked about something A-Fib doctors have long wanted—using a reduced A-Fib burden as a primary end point in clinical studies. (Most clinical studies have as an end point if a patient is A-Fib free, but sometimes a patient isn’t “cured” and isn’t completely A-Fib free but feels much better; i.e. has a “reduced A-Fib burden”.)

Animal Experimental Studies
Dr. Judith Davis offered attendees a new perspective as a Veterinarian who can help researchers design studies involving animals. Dr. Davis recommended animal studies have at least 4-6 animals. She pointed out some of the important anatomical differences in animals that researchers need to be aware of when designing experiments. For example, dogs and pigs are protected from having strokes because they have different intracranial artery structures and extra artery branches than humans.

New Irrigated Tip RF Circular Catheter
In the session on Advances in Catheter Ablation for Paroxysmal A-Fib, Dr. Pierre Jais gave a talk and a pre-recorded case presentation on a promising new Circular and Mapping Ablation Catheter being developed by Biosense Webster (the nMARQ circular and crescent irrigated catheters with Multichannel RF generator and Carto 3 3D mapping system). Previous circular catheters were non-irrigated and seemed to cause more TIAs and strokes. This adjustable catheter seemed to produce circular lesions relatively easily and effectively. According to Dr. Jais it’s better, faster and easier than standard RF point-to-point ablation. It takes him only 12 minutes to isolate all four Pulmonary Veins. The whole Ablation procedure takes less than an hour.

‘Reverse Remodeling’ Ablation—Medical Breakthrough!
Dr. Jais, in the session on Persistent A-Fib, gave a talk on an innovative strategy that seems to be a major medical development in the treatment of A-Fib—’Reverse Remodeling’” Prior to Ablation. One to three months before the ablation, the patient is electrocardioverted and put on dofetilide or class I or III drugs to get them in sinus rhythm before the ablation. The point of this is to reverse the electrical remodeling effect of persistent A-Fib at least temporarily (some of the physical remodeling effects of A-Fib like fibrosis are permanent and can not be reversed). Compared to a control group in persistent A-Fib, persistent patients cardioverted to sinus before the ablation needed less RF delivery and the number of non-PV A-Fib producing spots was reduced. The ECGI slides of patients in both groups were remarkably different with much fewer rotors, focal points, conflicting signals, etc. in the sinus group. 95% terminated to sinus rhythm compared to 77% in the control group. Final success rates were similar (but that’s because the Bordeaux 5-step protocol is very effective in curing Persistent A-Fib in most types of patients). Reverse Remodeling is very important for patients because it seems to make the procedure shorter, easier and creates much less catheter ablation burns on the left atrium. The studies he cited were very powerful. (See ‘Reverse Remodeling Ablation‘ below. )

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CryoBalloon Ablation

The number of EPs performing CryoBalloon ablations is increasing rapidly, even though Medtronics requires they  receive special training first. Over 35,000 CryoBalloon ablations have been performed worldwide at over 400 centers. Of the presenters at this year’s Symposium, Dr. David Wilber of Loyola Un. Medical Center, Chicago co-authored with Dr, Audrius Bredikis a book on Cryo “Cryoablation of Cardiac Arrhythmias” (2011 Saunders/Elsevier hardback $134).

Dr. Douglas Packer of the Mayo Clinic in Minnesota  gave a pre-recorded case presentation on the new CryoBalloon ablation catheter.  The “Even Cool” system, with eight freezing jets instead of four, provides better control and a more even freezing surface. The balloon when cooled actually attaches itself to the moving heart tissue (like if you stuck your tongue on a frozen flagpole), which makes for a more controlled, secure contact . But unlike RF, a cryo contact if misplaced can be allowed to unfreeze and then be moved without any damage to the previously cooled tissue. Whereas in RF ablation, when you make an ablation, it’s permanent. Cryo ablation generates less blood clots than RF ablation and is generally safer for patients. In Dr. Packer’s demo it seemed much faster and easier to make circular CryoBalloon lesions than RF point-by-point ablation. Cryo seemed to cause what I would call a better type of  heart tissue damage than RF. After a CryoBalloon ablation, heart tissue seemed whitened but normal. Heart tissue integrity didn’t seem compromised or weakened.  Whereas RF ablation is like burning your arm. There is a permanent scar, ugly-looking dead, fibrotic tissue, etc.

But CryoBalloon ablation is relatively new. We don’t have much long-term data. However, it’s encouraging and a testimony to its effectiveness to see so many EPs who previously did RF ablation turning to CryoBalloon ablation.

Focus on Stenosis (Inflammation and scarring or occlusion of the PV Opening after Ablation)

Dr. Douglas Packer from the Mayo Clinic, in a presentation on the Risks of A-Fib Ablation, discussed stenosis (a narrowing of blood vessels after A-Fib ablation)—a complication considered to be increasingly uncommon as ablation techniques have improved over the years.  But Mayo, as a nationally recognized A-Fib center, is often sent cases with “exotic” complications. Stenosis is seen more often than one would expect.

Dr. Packer stressed that A-Fib doctors need to be vigilant and should check ablated patients for stenosis after three months. (It usually takes six months for a severe case of stenosis to completely close a vein.) But only around 25% of A-Fib doctors really look for stenosis. If a patient has any significant pulmonary problems, from bronchitis to coughing up blood, complains of shortness of breath, develops pneumonia, etc., suspect stenosis unless proven otherwise. If caught early, angioplasty balloons and stents can often correct for stenosis. But these patients need to be re-checked probably for life, because re-stenosis can occur.

(Added 3/6/13) In good news for patients suffering from stenosis, Dr. Packer added that in Mayo’s experience, in many cases of complete stenosis or blockage, collaterals formed within two years. (Collaterals are new Pulmonary Veins that develop to replace the veins closed off by stenosis.) “The real issue is whether that is good enough to reduce symptoms. It depends largely on what the other vein on that side looks like. If it is also occluded, patients may remain very symptomatic.”

Among other complications, Mayo is also seeing:

• Cases of stiff left atrium, presumably because of excessive scarring of the left atrium.
• MRI studies have revealed Cerebral Micro Embolic events, but they don’t always cause symptoms and often disappear over time.  But they are certainly something everyone wants to avoid causing.
• Phrenic Nerve injury during CryoBalloon ablation usually goes away over time and is less of a problem with experience.
• (Added 3/6/13) Dr. Packer also mentioned “late tamponade” (an accumulation of fluid in the pericardial sac around the heart) probably due to oozing from an ablation or catheter site that recurs when patients are started back on anticoagulants.

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Last updated: Friday, February 13, 2015

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