Dr John Mandrola practices cardiac electrophysiology in Louisville, KY. He finished training at Indiana University in 1996. His practice encompasses catheter ablation, including an eight-year experience with AF ablation, device implantation, and consultative EP. Outside of the EP lab, Dr Mandrola's two hobbies include competitive cycling and writing. He has maintained a medical, fitness, and cycling blog, Dr John M, for the past two years.
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ESC 2012: Surgical AF ablation at the time of cardiac surgery. . . . Should we fix it while in there?Aug 28, 2012 08:38 EDT
"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.)
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.
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.