ESC 2012: Surgical AF ablation at the time of cardiac surgery. . . . Should we fix it while in there?

"While you are in there, go ahead and fix the atrial fib too."

This is the thinking behind adding surgical ablation when patients with AF are referred for cardiac surgery for another reason, such as valve repair/replacement, coronary bypass, or both.

When a patient goes to heart surgery, an opportunity presents itself. They are under anesthesia; the chest is open and the atria exposed. Why not try to get the AF, too? The concept is appealing and widely practiced in the real world, with cardiac surgeons using a variety of tools and strategies to accomplish "surgical AF ablation."

But is this approach wise? In which patients? Is it safe? What are the outcomes?

We simply don't know.

And this is why systematic studies of surgical ablation of AF come as welcome additions to the evidence base. Plus, there's a burden of proof when adding aggression to already-aggressive procedures. Doing [extra] runs counter to the less-is-more philosophy. The harder we look at preemptive therapeutics, the more we learn that less intervention is better. (Think not adding extra ablation to standard pulmonary vein isolation [PVI], not placing stents for asymptomatic coronary lesions, and not using intra-aortic ballon pumps in acute MI.)

The PRAGUE-12 trial, released today at the European Society of Cardiology 2012 Congress, compared cardiac surgery with and without left atrial surgical ablation. It was a three-center Eastern European trial that randomized 117 patients to surgery plus left atrial ablation and 107 patients to surgery alone. The primary efficacy outcome was the presence of sinus rhythm, measured with a single 24-hour Holter monitor, at one year. Safety outcomes included a composite of death, MI, stroke, or renal failure. The surgical procedure was left to the operator, but cryoablation was done in 97% of cases. Ablation was delivered epicardially or endocardially based on whether the left atrium was opened during the surgical procedure.

And the results . . .

Add-on surgical ablation increased the likelihood of sinus rhythm at one year—60% vs 35%. Surprisingly, the improvement was driven entirely by success in patients with long-standing persistent AF. Surgical ablation had no effect in patients with paroxysmal and persistent AF. Safety end points were similar in each group. (For a nice recap, see Michael O'Riordan's report on theheart.org.)

Some thoughts:

Starting with the positive: There were indeed some noteworthy aspects of the trial. It was the largest study of surgical ablation yet; it had a simple design; it encompassed a real-world cohort of true all-comers for cardiac surgery; and the two groups were comparable at baseline and in follow-up. What's more, it asked the right question: should we recommend surgical ablation to AF patients who are to have cardiac surgery?

The many limitations of this study leave us wondering about so much.

I'm confused as to why patients with paroxysmal and persistent AF did not benefit. How can this be? The authors speculate that it's due to sparse monitoring. That doesn't make sense because—for intermittent AF—less intense monitoring would make it more likely to see a benefit. As pointed out in the editorial, the lack of benefit in less-than-end-stage AF may have related to incomplete PVI—the same problem seen in catheter ablation. But unlike in catheter ablation, where total PVI is confirmed, surgical ablationists do not know whether they have created PVI.

Incomplete lines of block may also explain this study's effect on long-standing persistent AF. With just one recording attempt at AF, isn't it possible that surgical ablation simply converted long-standing persistent AF to paroxysmal AF? In this recent trial of surgical ablation—done in a very experienced center—left atrial surgical lines were incomplete 23% of the time. It's an important matter, as the presence or absence of any AF impacts anticoagulation decisions.

Another important question about surgical ablation is whether it reduces left atrial mechanical function. Think about it—after appendage removal, plus PVI, plus a mitral isthmus line, plus a LA roofline, what is left to contract? In this recent 150-patient study of surgical maze procedures, loss of atrial contractile function increased the risk of stroke fivefold. Of course, one could argue that if a patient remains in AF, they will have no mechanical function. That's true, but what about patients with earlier-stage AF that might be treated later with less extensive catheter-based approaches, which have now greatly progressed in both efficacy and safety?

Then there's the intriguing concept of left-atrial-appendage (LAA) excision as a means for stroke prevention. Also pointed out in an accompanying editorial, all patients in the ablation arm had LAA excision, yet the stroke risk was not lower. This finding lends credence to one blogger's opinion on LAA occlusion.

So what should we recommend to patients with AF who are to undergo heart surgery?

Before today, the evidence favoring concomitant surgical AF ablation was dubious. "Now we have a systematic prospective randomized trial that suggests no benefit in paroxysmal and persistent AF," wrote Drs Gerhard Hindricks and Christopher Piorkowski, from Leipzeig Germany.

So . . . what else could one conclude but . . .

Although every AF patient is different, and therefore a specific shared decison is necessary, I'd say in most cases of non–end-stage AF, it's probably best to "not fix it while you are in there."

Indeed, less may still be more.

JMM

References:

Budera P, Straka Z, Osmancik P, et al. Comparison of cardiac surgery with left atrial surgical ablation vs. cardiac surgery without atrial ablation in patients with coronary and/or valvular heart disease plus atrial fibrillation: final results of the PRAGUE-12 randomized multicentre study. Eur Heart J 2012:10.1093/eurheartj/ehs290.

Hindricks G, Piorkowski C. Surgical ablation of atrial fibrillation after the PRAGUE-12 study: More questions than answers. Eur Heart J 2012:10.1093/eurheartj/ehs294.

Conflicts: I make a living performing catheter ablation of AF.

Your comments

	ESC 2012: Surgical AF ablation at the time of cardiac surgery. . . . Should we fix it while in there?
	# 1 of 2	August 29, 2012 08:54 (EDT)
	Steve Clinch	61 yr old cv surgeon who did the triple bypass cycling ride 3years ago in Colorado-went into AFib post.Went back toDr  Kizer in North Carolina for an Ex-maze  procedure and has been in sinus  since.No evidence of valvular or coronary disease .If I needed open heart surgery would recommend atrial ablation with a stapler.Steve Clinch M.D. FACS
	# 2 of 2	September 10, 2012 01:50 (EDT)
	AL G	John's comments are good ones.  He points out a number of the problems with surgical Atrial Appendage closure(AA).  There are more. 1) increases cross clamp time and time on the  pump.  The result is a greater likelihood of milld brain damage(pump head syndrome). This is a widely occuring but almost forgotten complication of on pump surgical procedures. 2) Hormones that tell the patient they are becoming dehydrated are produced in the AA, as well as other locations. The result is that the patient will not realize he is becoming dehydrated until he is more dehydrated than he should be for good health.  The patient will have to remember to drink water regularly. It is  just like having to take medications 3 or more times per day.  We all know how poor the compliance rate is for meds that are taken more than 2 times a day. 3) The AA only accounts for about half of the clots, so it reduces, but does eliminate the need for blood thinners. 3) A significant %  of closures are not complete(20 to 35% in the studies I have seen).  This could cause an increase in clot formation rather than a decrease. 4) AA closure may leave rotors or other electrical circuits in the remnant AA but too far out to allow treatment by non surgical ablation. This is a bigger problem in closure of AA than excision of the AA, where bleeding complications are more likely.  5) ablating areas that are not contributing to  afib initiation results in an unnecessary decrease in atrial contraction.  Patients  with significantly decreased contractility have up to a 5 fold increase in strokes as well as altered hemodynamics with unknown consequences. 6) Longer procedure times increase the likelihood of other surgical complications like bleeding heart cell damage or death, increase in afib occurance, etc. 7)  Cryo ablation of the AA has inadequate success rates. 8) The Watchman device is even more problematic for a host of reasons well explained elsewhere. It is a really dumb device.  9) AA closure has a minor effect on hemodynamics but we have no idea whether that is a positive or a negative. 10) AA removal increases the chances for serious bleeding during or after the procedure.  11) It doesn't make sense to me that there would be an improvement in permanent a fib but not in more mild occurances.  The lack of at least 3  7 day monitoring to determine outcomes  makes any result far less believable. 12)  It is my view that surgical procedures, followed by an ablation 2 to 6 months, if necessry, will result in lower risk of complications and a higher success rate than surgical ablation in the majority of patients. I have no conflicts of interest and have no dogs in this fight over who gets the fees for ablation.

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