STS Guidelines Wrong to Call for More Surgical AF Ablation by John Mandrola

I pasted a copy so you do not need to log into Medscape.

The Society of Thoracic Surgeons (STS) recently published an extensive literature review and guideline statement on surgical treatment of atrial fibrillation.[1] The document was clearly written and well referenced. Its problem was the conclusions.

The authors, largely respected and experienced surgeons, call for more surgical ablation of AF. Their take of the literature is that surgical ablation is safe and provides long-term rhythm control; thus, we should do the beneficial procedure on more patients.

I strongly disagree—for three reasons.

Weak Evidence Base

The first problem with their conclusions is the literature itself. It's unconvincing. As an example, consider the evidence base for surgical ablation at the time of mitral-valve surgery. I chose this category because the authors give it a class I, level A recommendation.

Several of the cited trials of surgical ablation vs none are single-center studies with small numbers of patients, often less than 100 patients total. Most of these studies were published a decade ago and included only 1-year follow-up in which AF was assessed by a single ECG or Holter. Interestingly, as the electrophysiology community moves to more aggressive AF monitoring with implantable loop recorders (ILR), the surgical authors write, "[These ILR] systems have their own set of interpretive challenges and infrastructure requirements that may not significantly [affect] practice." To support less aggressive AF monitoring, the surgeons cite a study of 47 patients that found no difference between Holter and ILR recordings.[2] AF monitoring aside, these small studies yielded no useful data on long-term clinical outcomes such as rates of stroke or mortality.

The Cardiothoracic Surgical Trials Network (CTSN) investigators led the largest and most contemporary trial of concomitant surgical AF ablation during mitral-valve surgery.[3] This non–industry-sponsored multicenter randomized controlled trial compared surgical ablation or no ablation in 260 patients with persistent or longstanding-persistent AF. They found no statistical differences in 1-year mortality (6.8% vs 8.7% for the control group, P=NS). At 1 year, more patients in the ablation group were free from AF on a 3-day Holter monitor (63.2% vs 29.4%, P<0.001), but this did not lead to improvement in functional class or other quality-of-life measures. Patients in the ablation group were nearly three times more likely to require a permanent pacemaker (21.5% vs. 8.1% per 100 patient-years, P=0.01).

Surgeons from the Czech Republic reported nearly identical findings in a smaller trial of concomitant surgical ablation vs no ablation.[4] In this study of mixed valvular and coronary operations, ablation resulted in fewer AF episodes at 1 year but no difference in the rates of mortality, stroke, or heart failure. Pacemakers were required in 6% of ablation group vs 1% of the control group (P=0.07).

These studies confirm the results of many smaller studies and propensity-matched observational studies showing that, yes, surgical ablation can reduce the number of AF episodes noted at 1 year, but that does not translate into clinical benefits. Plus, surgical ablation comes at a cost. One cost is that the procedure adds almost $900 in surgeons' billing. (I know this because makers of the ablation tools conveniently post the reimbursement schedule online.) Another cost is a higher rate of pacemaker implantations.

The disconnect between suppression of AF episodes and clinical outcomes isn't surprising. The medical community has not yet decided on the strength of AF episodes as a surrogate marker of clinical outcomes. Witness the lack of temporal relationship between AF episodes and stroke. Many paragraphs in the STS guidelines make the case that having AF is bad and therefore fixing it is good. The problem is that there is no evidence that reducing AF episodes by drugs or ablation changes the disease course or reduces clinical events. Surgeons and electrophysiologists alike have trouble defining "success."

Lack of a Standard Procedure

My take of the surgical literature is that they haven't worked out a standard approach. In a 2010 editorial[5], aptly named "The longstanding, persistent confusion surrounding surgery for atrial fibrillation,"surgical pioneer Dr James Cox (Washington University, St Louis, MO) called the simultaneous introduction of new lesion patterns and new energy sources a violation of a cardinal rule of science. Namely, that all but one variable in an experiment be held constant. Cox wrote that the common practice of incriminating the energy source in surgical ablation failures rather than the lesion pattern was a "result of the influence exerted by industry on the mind-set of surgeons."

Here is my understanding of the complex history of surgical AF ablation: The cut-and-sew Cox-Maze III operation delivers the greatest freedom from AF. The problem is that it takes time (on pump) and expertise. The development of new tools, such as radiofrequency clamps, cryoablation probes, and even microwave energy sources led to the ability to approximate the cut­-and-sew procedure and reduce pump time. Putting new tools in the hands of innovative surgeons, however, has led to heterogeneity in lesion sets and energy sources. Some do right atrial lesions, some don't. Some do pulmonary-vein isolation alone, some do the full Cox-Maze. This hodgepodge of techniques complicates our understanding of the results.

In the CTSN[3] study, for example, the surgical ablation group was split into pulmonary-vein isolation only vs full biatrial Maze. In a group of patients with advanced mitral-valve disease, both techniques performed equally—an observation that surprised the surgical community. In a letter to the New England Journal of Medicine, Dr Cox called this finding "not valid" because the surgical technique was incomplete.[6] Most electrophysiologists would find this equivalence less surprising given the results of the STAR AF II trial. [7]

If surgical leaders can't agree on the best technique(s), what does that entail for translation of this procedure to the broader community where most heart surgery is done?

Surgical Ablation Requires Expertise

Here's a sentence from the STS guideline statement that included five references: "Based on available data, current ablation techniques are safe and should be applied at the time of open atrial procedures, even for high-risk patients." Four of the five referenced studies came from a single expert group of surgeons in the US, while the other came from one expert group in Europe.[8–12] That's the problem. It's hardly controversial to ask whether the safety and efficacy of surgical ablation reported in the literature can be replicated in the real world. The surgical authors did not cite a single contemporary database study supporting the translation of these procedures outside of expert centers.

At the risk of sounding like a neurosurgeon at an anticoagulation symposium, my experience with contemporary surgical ablation is not reassuring. I've done many redo procedures in patients who have had surgical ablation (from multiple centers). I find that the pulmonary veins aren't isolated and the mitral and cavotriscupid isthmus are only partially ablated. Often, there is significant delay of left atrial appendage activation—which suggests misplacement of lines. A basic rule of physiology is that partial ablation in the atria sets the stage for reentry. It's much easier to manage atrial fibrillation than an injured atrial flutter.

In a 2014 editorial, surgical ablation expert Dr Ralph Damiano (Washington University) echoed these concerns.[13] He noted the importance of surgical expertise and institutions' investment and commitment to obtain adequate follow-up. Damiano, a colleague of Dr Cox, also emphasized the importance of doing a full Cox-Maze lesion set. Despite the CTSN study,{3} he believes limited ablation is "less efficacious."

Conclusions

Considering the weak evidence base for surgical ablation (including no evidence of long-term clinical benefit), the lack of a standard approach, and zero published evidence it can be performed successfully outside of expert centers, only one conclusion is possible. We should not encourage more surgical ablation.

What we should encourage is more study of this technique. If I were in charge of healthcare, I'd allow this procedure to be done, but only by surgical groups who publicly report their clinical outcomes. I'd say no reimbursement without data. That would encourage surgeons to 1) record their results and add to our knowledge base, 2) learn to make complete lines, and 3) collaborate with electrophysiologists in the wise selection of patients.

13 Replies

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  • Yes I read this with interest. I'd been trying to find research on long-term safety and efficacy of ablation, and wasn't finding much. Two important points are: (1) More research is needed on long-term safety and efficacy of ablation; and (2) Ablation procedures are still being refined. Surgeons haven't reached some kind of plateau in the procedure - rather, refinements are still being made.

    Conclusion: don't rush into an ablation unless you really need to. If AF is making your life hell, then it's a great option. But don't do it simply to 'tweak' your mainly great life if your AF is manageable :)

    One question not addressed by this article: When is the best time for an ablation? Do we wait and wait until finally we're in permanent AF at which point - oops - we've missed the boat and the procedure has a low success rate?

    How do we know when the time is right?

  • I'm afraid I've three times opted for an ablation to tweak my life when it was OK and my AF was manageable.

    The decision surely depends on one's personal circumstances and I think it's worth considering how peeved one might be and how inconvenient it would be if one were to come to a sudden end in the Cath Lab. How much future - and what sort of future - does one hope for?

    There are no guarantees in life and every day fit, healthy people get up for an ordinary day and don't make it to the evening.

    For myself, apart from the fact that my husband would be disadvantaged in many ways, I'd not feel short changed if I expired suddenly but I own up to having slightly - or perhaps very - warped views.

    I don't quite expect to expire today, but I've always had doubts about being here this time next week. I think myself lucky if I wake up and find everything in working order. 'Live each day as if 'twere thy last' is, I think, not a bad way forward. My husband, who is older than I am, buys himself a 3 year Rail Discount Card. I get a one year one and I think I made a remark a little while ago about buying green bananas being extremely optimistic.

  • No regrets! If it worked for you, then it was the right decision :)

  • Certainly no regrets! I'm much better off. I still get AF though and so far have not accepted the offer of another ablation! I'm currently sitting on the fence.

  • I enjoy reading Dr Mandrola's slant on things. It is always affirming to come across a medic whose research and opinion supports one's own belief. Totally agree with your comments Thomps95 . If one searches far enough it is always possible to find a doctor who agrees with a particular concept of health. We are all different

  • Thanks Engmac, much appreciated. The decision over the ablation option, which is very individual, rests for me on a lot of homework (largely done now) and then after that 'gut feel' which is often overlooked and scorned but does simplify things e.g. I have Lone PAF stable for 3 years on just Flecainide and although my ablation success rate should be near 80%, my first thought when I wake up in the morning is when to reduce the pills not should I speak to my cardio/EP about an ablation.

    If AF came back then its back to the gut for another decision.

  • I don't think this article refers to ablations in general - only to surgical ablations - i.e. ablations on the outside of the heart where the surface is criss-crossed with cuts. This is typically through a small cut - mini-maze or a full blown open chest operation - cox maze.

    90% of ablations are either RF or cryo using a catheter and are carried out by an EP rather than a surgeon. These are not covered by the article above.

    I would not go for a surgical ablation unless it was after a series of failed standard ablations and I was genuinely desperate.

  • Exactly. Catheter ablations are another kettle of fish and even there risks differ depending on the technique. AF is progressive and until now only ablation stops it.

  • Good point :) here is an article comparing surgical and catheter ablation. It sounds like surgical ablation has slightly better outcomes. I would assume the risks of complication are higher in surgical ablation (but the article noted that the risks were "poorly reported" in the existing studies).

    ncbi.nlm.nih.gov/pmc/articl...

  • I agree with Mark - I read this article as surgical ablation and with other complications - NOT -catheter ablations.

    I would also point out that ablation is not a life saving procedure - it is performed for quality of life so to judge by mortality rates is not appropriate. It's like comparing bananas with apples - different fruits.

    People please do not confuse the findings of this report with a catheter ablation which the majority of us and all of us with Lone AF would be offered.

    Surgery by a cardio-thoracic surgeon is a different ball game.

  • If you want read the original statement sts.org/resources-publicati...

  • Thanks to EngMac for taking the trouble to do a critique of this study. However, I am unfamiliar with so many of the technical terms that I couldn't really follow the argument in many places. Does anyone know of a good glossary for this area of knowledge?

    Pat.

  • I hope that Bob does not mind me reposting his excellent explanation of the difference between surgical and catheter ablation, from a couple of years ago. It just seems very relevant to this post.

    BobD

    2 years agoBobD Volunteer

    Catheter ablation is minimally invasive whereas surgical, even the keyhole method is not. There are some good fact sheets on AF A website which explains a lot of the procedures and methods are changing over time. Briefly -----

    Radio Frequency ablation uses electrical energy to create heat to burn small spots inside the heart, usually around the four pulmonary veins which are the areas where rogue impulses are often found. The EP can stimulate the heart's electrical system to trace where these signals may be coming from. RF can also be used to draw lines across the atrium in other places.

    Cryo ablation uses a small balloon which can be inflated in the entrance to the PVs and into which a very cold gas is passed to create freeze burns. The burn and resulting scar is often more complete than with RF and if the PVs are the only places your AF is coming from this method is often successful first time. It cannot , however, deal with other areas for which RF may subsequently be required.

    Laser balloon is different again but basically the provisos of cryo apply.

    Surgical ablation as mentioned is highly invasive even the key hole method which makes the scars on the outside of the heart but as you say there is the possibility to remove the LAA which may allow anticoagulation to be stopped. Trials are being done using both the above and RF internal ablation.

    Internal surgical ablation would normally only be used during other open heart surgery.

    There is no one size fits all I'm afraid and it would be wrong to say that RF is better than Cryo or vice versa as it depends where the signals originate. Personally I would need to be very ill with AF to consider surgical procedures but that is just me.

    Hope that helps

    Bob

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