Pulsed Field Ablation for Pulmonary Vein Isolation in Atrial Fibrillation

[www.practiceupdate.com]

Not sure if you’re link is working for everyone but here’s a similar link.

[www.ncbi.nlm.nih.gov]

Looks broadly promising - particularly from a safety profile viewpoint - overall, but not sure about this bit (from the full article):
“Secondary endpoints
Of 62 patients scheduled for remapping, 52 (84%) actually presented for this invasive PV reassessment at a median of 84 days following the index procedure. With successive refinements to the waveforms, the proportion of patients (and PVs) with durable electrical isolation progressively improved from 18% of patients (45% of PVs) with the initial waveform (monophasic) to 100% of patients (100% of PVs) with the most optimized waveform (biphasic-3) (Figure 3). The remapping procedures were performed without complications. ”
Please correct me but does the above mean that only 18% of patients had successful PV isolation 3 months after the index procedure?? If so, looks very much like 2 goes are required - and more so than is the case with RFA?.



Edited 1 time(s). Last edit at 07/25/2019 04:19PM by mwcf.

Quote
mwcf
Please correct me but does the above mean that only 18% of patients had successful PV isolation 3 months after the index procedure?? If so, looks very much like 2 goes are required - and more so than is the case with RFA?.

No, that section is really badly worded. I had to go find the full text and read it to understand what they meant. What they're talking about there is that they broke the study into groups that received different types of waveforms. There was monophasic and three flavors of biphasic. The monophasic approach yielded only an 18% success rate, but the biphasic 3 approach yielded a 100% success rate. Yes, 100%.

That kind of success rate combined with the near total lack of complications (a single pericardial effusion in the whole study), the speed (avg. 92 minutes), the lack of need for general anesthesia, and the lack of risk to the esophagus and phrenic nerve makes this nothing short of huge. The afibbers out there who are considering ablation but haven't done it yet should seriously consider holding off until they can find a center that offers this.

After reading the entire study it appears that the hundred percent comes after the second visit where any breaks in or incomplete PV isolations were isolated with standard RF frequency catheter.

So all participants had two complete procedures. The second consisting of remapping and PVI repair if needed. I didn’t see anywhere where they stated how many PVI isolations needed to be re-done during the follow up procedure.



Edited 1 time(s). Last edit at 07/25/2019 10:08PM by rocketritch.

Quote
Carey

That kind of success rate combined with the near total lack of complications (a single pericardial effusion in the whole study), the speed (avg. 92 minutes), the lack of need for general anesthesia, and the lack of risk to the esophagus and phrenic nerve makes this nothing short of huge. The afibbers out there who are considering ablation but haven't done it yet should seriously consider holding off until they can find a center that offers this.

So anyone know if Natale is using this? Also, if so would he be combining it with the usual RF technique to ablate areas other than the PVs?

Quote
rocketritch
So all participants had two complete procedures. The second consisting of remapping and PVI repair if needed. I didn’t see anywhere where they stated how many PVI isolations needed to be re-done during the follow up procedure.

True. I wish they had broken out the number that needed RF touch up. I assumed some or even most didn't, but even if they all did, a 100% success rate with two procedures is unprecedented. If numbers like that hold up to further trials, this is going to be a game changer.

Why does it not require anesthesia?

Thanks Carey and rocketritch for your input.

I'm still a bitt confused and in some ways underwhelmed. And as someone who will more than likely require a touch-up procedure at some point, I really want to buy into this PFA stuff!

From the full text:

"With successive waveform refinement, durability at 3 months improved from 18% to 100% of patients with all PVs isolated."

To me the term 'successive wafeform refinement' sounds like PFA rather than RFA (and the abstract mentions nothing about RFA being used the second time around)....Now maybe this bit IS key and I'm just not getting it yet, but but then in "Follow-up':

"Patients were planned for repeat invasive electrophysiological mapping at 75 days (PEFCAT) or 90 days (IMPULSE) after the index ablation procedure. During this repeat procedure, the LA-PVs were assessed for PV reconnection using a multielectrode catheter. If electrically reconnected, a standard irrigated radiofrequency ablation catheter (Thermocool, Biosense Webster) was used to ablate the point of PV reconnection."

Why did they use RFA for the second procedures? I'm still baffled as to whether all or just some second procedures were done with RF - I mean why the first quote above from the abstract talking about 'successive wafeform refinement'? Or is what is being said here that 100% PVI WAS achieved in some patients with 'successive waveform refinement' with the first PFA procedure alone, and it being those patients who didn't benefit from the 'successive waveform refinement' during their first procedure that required the RF touch-up? And what's the deal with PEFCAT at 75 days vs IMPULSE at 90 days? Why not just use one or the other??

I'd still be a lot happier if both the index and touch-up procedures had been done with PAF. As for freedom from AF success rates at 12m, let's also remember here that 80-odd percent isn't any better than success rates at many top centres with one RFA index procedure (for youngish paroxysmal-only AFrs as was the patient cohort for the subject article).

Now I want to be as enthusiastic about PFA as the next person but I must say overall that I'd be way more impressed if BOTH the first and second touch-up procedures had been done with PFA. The undoubted safety profile of PFA is by the fact that so many patients still needed good old RFA touch-up procedures to finish the job off.

But that said and even in the worst case - and given that the vast majority of overall ablating over two procedures (i.e. index and touch-up) is done during the first index procedure, then on the positive side using PFA for the index procedure still obviously a big step forward safety-wise.

Timescales-wise, when I chatted with Prof Jais (co-author of the subject article) at Bordeaux last August after my RFA PVI, he didn't think that PFA would be widely available for another 4 years i.e. 3 years from now. (EDIT: Prof Jais was very excited/animated/enthusiastic about PFA and he's actively involved in its development and was/is a co-author of this paper we're talking about.)

It would be great to get Natale's take on all of this in terms of what he thinks of it and, if he's a fan, when he thinks it will be widely available for index PVIs for AF. Maybe Shannon can get Natale's take in this regard at some point in the not-too-distant future.



Edited 1 time(s). Last edit at 07/26/2019 06:59AM by mwcf.

Another article about it.

"Safety is the biggest benefit of PFA and the "results of this first in human study are very impressive to say the least," commented John Day, MD, of Intermountain Medical Center Heart Institute in Salt Lake City, Utah.

If further studies support these findings, PFA could "disrupt the Afib ablation market" as it shortens procedure times and decreases the need for redo procedures. "I could easily see this technology replacing radiofrequency and cryo energy sources for the treatment of Afib," he speculated."



[www.medpagetoday.com]

[www.innovationsincrm.com]

Not as recent as the other links, but here is another Article with Webcast Videos from Heart Rhythm 2019

If Natale was doing this Shannon would have been talking about it.

I asked my EP about this last month, and he thought it was a ways off from being available, unless I got in on a Study.



Edited 1 time(s). Last edit at 07/26/2019 06:55AM by The Anti-Fib.

Quote
mwcf
Why did they use RFA for the second procedures?

Because they have RF catheters that can do single burns with accuracy to close a small gap, but the PF catheters can't do that (yet).

The paper isn't written well. It's rather confusing and leaves out some important details, but the take away is that once they settled on using the biphasic 3 waveform they achieved 100% success. I don't believe any single patient received more than one type of waveform.

Quote
Carey

The paper isn't written well. It's rather confusing and leaves out some important details, but the take away is that once they settled on using the biphasic 3 waveform they achieved 100% success. I don't believe any single patient received more than one type of waveform.

That’s an understatement? I’m curious as to why they wrote this as they did. Or if this was just a rough draft as this wouldn’t be acceptable for someone looking for FDA approval.



Edited 1 time(s). Last edit at 07/26/2019 05:06PM by rocketritch.

Quote
Carey

Why did they use RFA for the second procedures?

Because they have RF catheters that can do single burns with accuracy to close a small gap, but the PF catheters can't do that (yet).

The paper isn't written well. It's rather confusing and leaves out some important details, but the take away is that once they settled on using the biphasic 3 waveform they achieved 100% success. I don't believe any single patient received more than one type of waveform.

Carey,

Thanks for clarifying re using RF for the second procedures.

In your second sentence, do you mean that the first procedures using the biphasic 3 waveform maintained 100% PV isolation with no need for a second procedure??

Mike and Anti-Fib l, I’ll write more tomorrow, Saturday, regarding PFA and Electroporation ... and yes, Dr Natale is very familiar with it all and has been actively investigating electroporation or some time now, via Medtronics design for PFA, as well as working with BioSense Webster and Abbott on their respective designs for PFA systems.

Its a very exciting development long term and yet I'm looking forward to discussing more about the tech, and in the meantime please keep in mind it is very early still in this entire development process and in spite of the very promising initial findings, there is still a lot more work ahead.

Have been laid up regarding typing and repetitive use of my hands in recent months. And in the last two weeks I’ve started the first phase of a two part process to hopefully restore long term hand function by the end of the process with the guidance of a highly respected hand surgeon. Hence my relative absence from the forum over the last 6 plus months.

Nevertheless, I’ve still been very much engaged by phone with a constant source of forum Afibbers who are at that place in their AFIB history that they urgently want to be rid of all atrial arrhythmia, and as Ive done for years now, I've been discussing their options and assisting them in that process by phone.

Ive also been in close contact with Carey frequently who has been a huge help to me and, indeed, to the whole forum which is very much appreciated. Just as I very much appreciate all the dedicated support so many of you regulars have contributed to our wonderful online AFIB resource!

Will make an effort to review my take on this very cool new PFA technology during this coming weekend, while also pumping the brakes just a little bit on folks perhaps getting a bit too far in front of their ski’s on the topic. It is very promising, indeed, but it’s not just around the corner either.

Will save the rest for this weekend when I am due to get my Macbook Pro computer back from Apple after the last 10 days with zero computer due to a sudden black screen failure on a just less than one yr old machine ... when it rains it sometimes pours, eh?! :-)

Cheers!
Shannon

P.S. The article linked to in this tread on PFA leaves a good deal to be desired in clarity and accuracy, as Carey and others noted.

The following is a good quote about the study Follow-Up: “During follow up of the two non-randomized trials referenced: (PEFCAT: with a repeat invasive EP mapping study at 75 days after index ABL) and (IMPULSE: a similar repeat invasive EP mapping study at 90 days after index ABL). During this repeat procedure, the LA-PVs were assessed for PV reconnection using a multi-electrode catheter. If any PVs were reconnected, a standard irrigated Thermocool RF catheter was used to ablate the point of PV reconnection. A voltage amplitude map was again created.”



Edited 2 time(s). Last edit at 07/27/2019 04:57PM by Shannon.

The main benefit of PFA Mike is, indeed, the safety aspect. There is some degree of potential efficacy benefit for PVI. particularly with less experienced ablation EPs ... but not so much of an ‘efficacy’ advantage for highly experienced elite level operators. More this weekend.

Shannon



Edited 1 time(s). Last edit at 07/27/2019 04:59PM by Shannon.

Thanks Shannon and hoping the hands respond well soon.

And yes that article was/is indeed very difficult to get to grips with and I still haven't! But that said, I do now increasingly appreciate that safety - and particularly in the hands of less experienced operators - is the main advance intrinsic to PFA. I'd very much still like to interpret the article whereby the first PFA procedure using biphasic waveform 3 achieved 100% PV Isolation at 3 months follow-up!!

Looking forward to your further response on this exciting area of advancement in due course. Not least some clarification on that article which also had Carey scratching his head somewhat I think and he's quicker and more exacting on the uptake than most!

Cheers,

Mike

Not sure if this is a stupid question: does the PFA ablation address sources of afib outside the pulmonary veins or just the PVs?

Yes Callydex,

This preliminary approach to Pulse Field Ablation is limited to only doing a PVI ... so far. No doubt, as the technology matures, the developing companies will expand the catheter designs and overall supportive systems to allow more flexible ablation for more challenging cases of AFIB like so many of us on Afibbers forum have either required, or are waiting to have a more comprehensive ablation to address more complex and more advanced forms of atrial arrhythmia.

At this point and while very encouraging, there have only been a very few human studies on PFA and most of the research to-date has been on animals. I thus strongly suggest that while its perfectly understandable to be excited about the genuine major potential of PFA in the coming years ... unless you are needing only a PVI alone for a relatively early stage paroxysmal case over the next three years or so, I urge anyone who is fed up with living with a progressive form of AFIB to not cancel any planned or projected ablation set within the coming year or so.

This recommendation is primarily meant for those who follow our Afibbers Forum's strong advice to only choose the most experienced maestro level EP to be in charge of one's expert ablation process .. regardless of the type of energy source used in that process.

I do not want to see folks get so excited over the unquestionably very powerful potential of PFA, that they understandably might jump the gun a bit and assume that PFA development will all mature very quickly and for all degrees of AFIB ablation difficulty. Such an assumption could pose a very big risk, in my view, for their already progressive AFIB may well get much worse in the next few years while waiting for PFA to finally hit the prime time!

And all the while, such folks who are already in line for an expert ablation to get rid of the beast for good, might well go on to develop persistent or LSPAF during such an uncertain waiting period.

Plus, assuming our readers will insist on making a very discriminating choice for an elite EP to begin with, while there are still some significant safety benefits for PFA ablation, such top level RF maestros already offer extremely safe ablations, as is. Plus, they offer ablations whose long term efficacy in freeing patients from all atrial arrhythmia we can already truly vouch for.

If full PFA technical maturity were, say, 6 months to even perhaps just a year away, maybe that might tip the scales towards a stronger argument for waiting.

However, I witnessed a fair number of Afibbers get very excited from the initial enthusiasm promoted by the FIRM mapping and ablation champions. And, indeed, some of these folks I spoke to at length ignored our plea's to not jump the gun and they canceled ablations they had set up in the hope that FIRM would prove to be the ultimate 'one and done' procedure ... we all know now how that turned out!

Now, I want to be clear, too, that PFA is far more exciting and solid in concept than was FIRM mapping. FIRM was speculation on 'where to ablate' while PFA is based on the far more solid "How to ablate". Especially since the fundamentals of PFA deal with DC energy and Electroporation ... both of which are far better known and understood than were the speculative concepts around 'rotor' mapping and ablation.

Nevertheless, with the very limited PFA research so far, we only have seen 120 days of actual follow-up in a relatively small group of humans, and with a number of important caveats listed in the "Study Limitations" section of the latest exciting and impressive study.

https://doi.org/10.1016/j.jacc.2019.04.021

When choosing among less experienced clinical EPs who typically only offer a PVI alone when their patients ask for it, in that scenario, a stronger argument can be made for early stage paroxysmal Afibbers who are currently in no hurry at all to get rid of their AFIB while waiting for PFA to mature, due to the somewhat added safety risks from less experienced operators.

However, if anyone in our group is seriously planning on rolling the dice by compromising on a modestly experienced ablation EP, they would be embarking on the wrong footing in any event in my view.

I do feel very confident that Electroporation will become the primary energy source for most future ablations, but there is still a good ways to go before we know for sure that there are not any 'gotchas' that only more in-depth and larger volume research might reveal.

And being optimistically cautious and let the validation of PFA ablation come to us, has been the main theme I heard over and over at HRS Scientific Sessions in San Francisco this past May, rather than letting our enthusiasm perhaps put the cart before the horse which would be so easy to do for such a cool technology! This was the prime recommendation I heard repeatedly at HRS Scientific Sessions regarding letting this tech prove itself over the coming few years and only then roll out the red carpet once PFA is very well matured.

A few other points in speaking with Dr Natale last night ... As noted, he is very much involved in the early research of PFA, working in conjunction with Medtronics, Biosense Webster's and Abbott's respective designs for PFA technology.

1. It was also noted that general anesthesia will still be preferred for most ablations, and even with a good many different PFA waveforms used as an energy source. Apparently, only one or two specific Biphasic PFA waveforms allow for use of conscious sedation with Propofol but without GA (general anesthesia). Most other known Biphasic waveforms .. and certainly, without question, all Mono-phasic PFA waveforms ... will require GA still.

2. For the fore-see-able future, the current technology and catheters for PFA are suitable only for PVI alone. The current PFA basket and flower shaped catheters are designedf to fit within the PV antrum's 'funnel-like' neck area of each PV and thus is not yet suitable for focal ablation nor for posterior wall isolation, nor LAA Iso etc. etc.

3. Keep in mind too, that PFA's prime benefit is in it's inherent enhanced safety. However, just using a PFA energy source will not inherently turn an average ablationist into a maestro expert! The EP still will need to know what, where and how to ablate.

4. We also still need to confirm the very promising preliminary research referenced in the link above, via much larger human trials comparing PFA directly to well-vetted thermal ablation techniques must be done over the coming years.

5. We still need far more work in validating the efficacy of numerous BiPhasic waveforms used for various areas of the two atria and confirming truly long term durable isolation is, indeed, maintained over time with PFA. So far, the longest follow-up in humans is just 3 months.

All that being said, this is all truly promising technology and I do feel that with a good deal more patience and hard work, PFA holds tremendous promise to help usher in a new era of shorter and extremely safe ablations. The good news, too, is that much of the inherent safety of PFA will be there almost regardless of the operator!

There is a lot more to the story, so stay tuned as we bring you more updates as they occur.

Cheers!
Shannon



Edited 1 time(s). Last edit at 07/28/2019 03:28AM by Shannon.

Thanks for the clarifications !

Cheers Shannon.

From the link you provided (and that I read very carefully this time):

“PFA’s qualitative safety edge also has meaningful implications for the durability of electrical PV isolation—arguably the most meaningful endpoint in AF ablation procedures—given that the primary mechanism of recurrence following ablation is electrical PV reconnection. Because multiple PFA lesions could be placed per vein without paying a safety penalty, as the PFA waveform was optimized to the final refinement (i.e. biphasic 3 - my words), the durability of isolation (i.e. at circa 3 months - my words) in this subset of 18 patients improved to per vein and per patient rates of 100%. For comparison, no thermal ablation technology has been able to demonstrate such a low rate of PV reconnection; indeed, the published rates of durable isolation on a per-vein and per-patient basis have ranged from 51% to 93% and 21% to 79%, respectively.”

And all with a hugely superior safety profile. Definitely a game-changer to me. Fingers crossed there are no unforeseen hiccups (and lets remember here that electroporosis has been around for quite a long time in other medical arenas) and that it’s available as first-line AF ablation in 3 or 4 years max.

(EDIT: when I met with Prof Jais (a co-author of the subject paper) last August, I asked him whether one could have a PFA ablation after one had had an AF reoccurrence after a prior RF ablation and he said absolutely no problem.)



Edited 1 time(s). Last edit at 07/28/2019 02:56PM by mwcf.

A bit more on Farapulse PFA:

“FARAPULSE Receives FDA Breakthrough Designation for its Endocardial Pulsed Field Ablation System”

[www.prnewswire.com]



Edited 1 time(s). Last edit at 07/28/2019 04:37AM by mwcf.

The question I have Mike, is what if your recurrence is from a focal trigger such as an atypical left flutter ... or even a CTI flutter source within the right atria far away from the PVs??

It would be very hard to tell beforehand just where your recurrence is originating from, but I suppose he could always just switch back to RF in that case since the only PFA catheter, so far, offered by Farapulse (the PFA company that the Bordeaux team is supporting and that at least Prof. Jais, if not others at Bordeaux too, have bought stock in. To the best of my knowledge, Farapulse only has either a ‘basket’ or ‘flower’ shaped catheter that is strictly meant for use within the ‘funnel’ part of a Pulmonary vein antrum.

Perhaps he meant conceptually it could be done or he may have been assuming your recurrence is from a leak in one of the four PV’s.

The odds are less that in a case like yours with a highly experienced operator like Dr Jais, that you would have had a PV reconnection at all. it can certainly happen, even with an elite operator, but I rarely ever see a direct PV reconnection from a highly skilled maestro with all the legions of ablation reports I’ve read.

Such PV reconnections are common with less experienced clinical EPs doing ablations on the side, in addition to doing a wide range of other EP procedures, but most elite operators have, by now, got a durable PV isolation down pat where a finding of a PV reconnection in a follow up ablation of a patient they did the index ablation on is more of an exception than the rule.

Cheers!
Shannon



Edited 1 time(s). Last edit at 07/29/2019 10:47AM by Shannon.

Hi Shannon,

Thanks for the further input.

When I asked Prof Jais whether or not one could have PFA after a RFA I was thinking mainly conceptually (I’d only had my ablation the previous day) but also for any later possible - albeit (hopefully) unlikely - reconnection of the PVs as it’s clear that - for now at least - PV isolation is ‘all’ PFA can do.

Cheers,

Mike