My 2nd Report: More from the 2016 Western AF Symposium
Second in a series By Steve S. Ryan, PhD
This is my second report on The Ninth Annual Western Atrial Fibrillation Symposium held February 26-27, 2016 in Park City, UT. Look for my first report with 9 brief summaries.
Introduction: After having just attended the January 2016 AF Symposium in Orlando, FL, I was surprised at how much new, relevant information was provided (sometimes by the same presenters). In all, there were 53 scheduled presentations of 15 minutes each.
This time I cover 6 brief summaries of technical presentations.
A New Ablation Parameters Concept for an Accurate Lesion Assessment During AF Ablation
Dr Moussa Mansour discussed the Biosense Webster’s Thermocool SmartTouch irrigated tip ablation catheter with force sensing technology and the St. Jude Medical’s TactiCath (Endosense) contact-force sensing ablation catheter. Each provides the operator with force and contact info which both lowers PV reconnection and the need for repeat ablations.
The newer contact force sensing catheters will also integrate not only force and contact info but also duration, power, catheter stability, and temperature to accurately predict lesion depth and quality. In one system, lesion tags will be automated. A (completed) lesion tag will only be displayed if the lesion meets pre-set criteria.
I’d like to put together a ‘Steve’s List’ of EPs using contact force sensing catheters, but I can’t get the information from the manufacturers (Biosense Webster and St. Jude Medical).
Contact force sensing catheters are a huge improvement in RF ablation. You should insist on an EP who uses contact force sensing catheters. Ask your EP office staff if they use contact force sensing catheters. If they don’t know what you are talking about, contact another EP.
Rotors in Human AF: Multicenter Experience
Dr. Gary Tomassoni has been using the FIRM 64 electrode basket mapping catheter to perform ablations. He uses FIRM-guided ablation in conjunction with PVI.
In his experience rotors are stable and are critical to success. He tailors his ablations to the location of the rotors which he uses as the anchors of the procedure. He starts with the right atrium, then moves to the left. In general, termination during the procedure works better than having to electrocardiovert the patient back to normal sinus rhythm.
Anticoagulation During AF Ablation: Multi-Center Experience
When using an open irrigated RF catheter along with warfarin, Dr. Natale’s group reported no stroke/transient ischemic attacks in 2,618 ablation patients even though they had a higher prevalence of nonparoxysmal A-Fib and higher CHADS2 scores. [In previous studies, patients with Persistent/Permanent A-Fib were more likely to develop strokes during RF ablation.] In a smaller study, uninterrupted rivaroxaban (Xarelto) during RF ablation reduced silent cerebral ischemia as detected by dMRI.
In a small study of apixaban (Eliquis) compared to warfarin, there were no strokes/TIAs and no silent cerebral ischemia in the apixaban group.
Dr. Natale concluded that uninterrupted Xarelto and Apixaban seem to provide the same protection as uninterrupted warfarin, though more data and studies need to be done to verify their safety.
He stressed that anticoagulation should be started before the transseptal puncture rather than after. [From the O.R. reports I’ve read, this doesn’t seem to be normal practice.]
Fiber Optical Balloon: Experience and Long-Term Outcome Data
Dr. Edward Gerstenfeld showed video and slides of the CardioFocus Laser Balloon Catheter (not yet approved for use in the US). In addition to the operator being able to see directly where he is ablating through optical fiber, the balloon is compliant and can adapt to the individual contours of the pulmonary vein. 99% of PVs were isolated with the balloon alone.
Results are similar after 1 year to irrigated RF ablation. Over 7,000 ablations using the Laser Fiber Optic Balloon catheter have already been performed in Europe. See my article on Laser Balloon Catheter.
Long Term Follow Up on Patients with Failed Ablation of AF
Dr. David Callans pointed out that patients with a successful A-Fib ablation do better than A-Fib patients without ablation in terms of three-year mortality and stroke. A study of 3,355 patients at 3 centers over four years who had a successful A-Fib ablation, found those patients had very little stroke risk even compared to patients still taking anticoagulants.
Of patients not taking anticoagulants who had a CHADS2 risk score of greater >2, none had an ischemic stroke (A-Fib related stroke). Whereas in the group still taking anticoagulants, 2% had a hemorrhagic stroke vs 0.04% of those not taking anticoagulants.
But what happens to patients with a failed ablation? Dr. Callans asked, are their A-Fib symptoms worse? Are they at increased risk of stroke despite anticoagulation? Are they more likely to die (increased risk of mortality)?
In a 3-year follow-up study of non-paroxysmal A-Fib ablation at the Un. of Pennsylvania, the answers to these questions were not good. In the group that remained in persistent A-Fib (n=62), 20 had at least one repeat ablation. 96% remained on oral anticoagulants [I wonder: why weren’t 100% on anticoagulants?]. But A-Fib symptoms were generally manageable with rate control drugs. During the 3-year follow-up:
• Four had an AV Node Ablation and Pacemaker procedure (usually a measure of last resort; see my article, Ablation or Modification of the Atrioventricular (AV) Node and Implanting a Pacemaker)
• There were three deaths
• There were two strokes and one TIA (Transient Ischemic Attack, i.e., a temporary “mini-stroke”)
• There were two episodes of serious bleeding
Because of the small numbers, it’s hard to draw significant conclusions. But mortality was significantly higher in the group that remained in persistent A-Fib. This increased risk of mortality may be tied to increased comorbidities (i.e., obesity, diabetes, hypertension, sleep apnea, etc.) in this group.
Monitoring AF After Treatment: How Long and How?
Common practice today is to wait to assess the efficacy of catheter ablation for at least three months following catheter ablation—the “blanking period.”
But Dr. Suneet Mittal discussed the importance of monitoring AF burden (the amount of time the patient spends in A-Fib) during the blanking period. Dr. Mittal found that patients with more AF Burden during the blanking period were more likely to have recurrence. 100% of the patients studied with a >15% AF Burden during the blanking period experienced recurrence.
He also found that Intermittent Rhythm Monitoring (IRM) such as by 24-hour Holter monitors is significantly inferior to Continuous Monitoring (CM) by devices such as the Reveal LINQ Insertable monitor which a patient can have inserted under their skin for up to three years. Typical short-term monitoring (IRM) after an ablation may miss a great deal of A-Fib burden and chance of recurrence. But it may not be realistically possible to implant a CM device in all A-Fib patients.
Dr. Mittal recommended that current guidelines be changed to continue monitoring after an ablation. He added that after an ablation patients should be encouraged to take their pulse to monitor for irregularity and asymptomatic A-Fib episodes.
Report 2: Wrap Up Highlights
From the perspective of an A-Fib patient, the most exciting news was about developments to improve Contact Force sensing catheters. (They are already a huge improvement in RF catheter ablation). In addition to providing the EP with force and contact info, the new catheters will integrate duration, power, catheter stability and temperature to improve ablation quality.
The Laser Fiber Optic Balloon catheter seems also to have great potential. But we just don’t know if it will ever be approved for use in the U.S.
Dr. Callans pointed out that patients with a successful A-Fib ablation had very little stroke risk. Where as of those still taking anticoagulants after a successful ablation, 2% had an hemorrhagic stroke. Putting patients on anticoagulants after a successful catheter ablation is both ineffective and dangerous.
Dr. Mittal, and many at the Western Symposium presenters, expressed the increasing awareness that people over 65 need better monitoring than just an annual office ECG. The goal should be for everyone over 65 to have a practical form of continuous monitoring to detect A-Fib before it becomes a problem (i.e., causes a stroke). The challenge is finding a practical, cost-effective way to offer continuous monitoring to everyone over age 65. This is a major public health issue.
If you are on the NOACs Xarelto and Eliquis, Dr. Natale’s data is encouraging news. When having an ablation, you don’t have to switch back to warfarin beforehand. (They couldn’t say that about Pradaxa, see Pradaxa Danger Ablatlion—Switch to Warfarin.)
Also very encouraging, was Dr. Natale’s data that there were no strokes among the 2,618 ablations performed by his groups. This is especially impressive because among their patients, there was a higher prevalence of nonparoxysmal A-Fib and higher CHADS2 scores. (Translation: Their patients had more severe cases of A-Fib and more risk factors for stoke.) Could we be close to dropping ‘stroke’ as a possible complication during an ablation?
Look for my third report in the series in the coming weeks.
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