EXECUTIVE SUMMARY

The Society of Thoracic Surgeons has set new guidelines to help surgeons make better decisions regarding surgical strategies for atrial fibrillation.

  • The guidelines find that surgical ablation for atrial fibrillation poses no additional risk at the time of concomitant mitral operations to restore sinus rhythm.
  • Concomitant surgery with closed atrium also shows greater benefit than risk.
  • Stand-alone surgical ablation for atrial fibrillation can be beneficial, depending on the circumstances.

The Society of Thoracic Surgeons (STS) recently issued its 2017 clinical practice guidelines, aiming to improve surgical outcomes for atrial fibrillation (Afib) and reshaping the surgery field’s common practices in dealing with this condition.

“We have new information that wasn’t available for previous guideline statements, and the quality of studies is better,” says James R. Edgerton, MD, FACC, FACS, FHRS, co-director of the Atrial Fibrillation Center for Excellence at The Heart Hospital Baylor Plano, associated with Baylor Healthcare System in Plano, TX. Edgerton is a co-author of the new clinical practice guidelines for Afib.1

The STS guidelines, published in late December 2016, are part of a trend whereby professional medical societies help physicians distill the large quantity of studies and new practices to determine best practices for their own patients.

“Various professional societies increasingly are putting out guidelines to help with clinical care,” Edgerton notes. “In general, medicine is changing as we move into the information age, and there is so much information available to doctors now through the internet and excellent search engines like Google Scholar, MedEd, and Medline.”

For Afib guidelines, STS experts digested 1,000 articles, distilling them down to the best 166 that were used to form the guideline recommendations. Each was analyzed by a team of experts and used to inform a consensus review that led to the 13-page guidelines, Edgerton says.

The guidelines condense an enormous amount of information for surgeons. “Even though I am quite aware of the literature, I can’t keep 166 papers in my head, so this is very helpful for doctors in their day-to-day practice,” he says. “Most surgeons will read the executive summary, which presents the recommendations. In the body of the manuscript, we explain the evidence supporting each guideline statement.”

The estimated 2.7 million Americans who live with Afib have rapid, disorganized electrical signals that cause the atria — upper parts of the heart — to quiver, and the quivering upsets the normal rhythm between the atria and the ventricles — lower parts of the heart. So the ventricles beat fast without a regular rhythm, which can lead to blood clots, heart failure, stroke, and other complications.

Surgical ablation can affect these patients’ long-term outcomes by returning them to normal heart rhythm and reducing stroke risk.

STS experts found in reviewing the literature that, in some situations, the benefits of surgically correcting the Afib far outweigh the risks of the procedure. In other situations, the benefit to the patient may not outweigh the risks; recommendations are given accordingly. The society’s 2017 guidelines summarize 30 years of Afib treatment development into a consensus paper that concludes surgical ablation is effective in reducing Afib and should be offered as a treatment more often than it is.

The creators of the guidelines took a different approach, dividing Afib into three categories and telling surgeons what the best research suggests should be done in each of those categories, Edgerton says.

About 40% of patients are not receiving surgical ablation for Afib when the new guidelines say it would be of benefit, he says.

“It is not being done because surgeons were concerned that the procedure added too much risk or too much time,” Edgerton says. “They think it’s too risky, not effective, too hard, or they don’t agree that it should be done, but the new guidelines give clearer direction derived from recent studies.”

The first clinical ablation procedure for Afib was in 1987 by James Cox, MD, who had researched this method extensively and called it Maze I. Updated methods were called Maze II and, since 1992, Maze III.1

All ablation is based on the fact that electricity cannot jump a scar, Edgerton says.

“We found we can channel electricity in the atrium by strategically placing scars on the atrium, and Jim Cox did that work from 1987 to 1992, making these breakthroughs,” he explains. “He strategically placed scars on the atrium to channel electricity, leaving only one pathway to the lower ventricles.”

The STS recommendations provide guidance on how to assess when the surgical ablation is warranted. Edgerton and the guidelines describe each category, as follows:

  • First category: Surgical ablation for atrial fibrillation poses no additional risk of operative mortality or major morbidity if it is performed at the time of concomitant mitral operations to restore sinus rhythm.1

Edgerton explains what a “concomitant ablation” is: “If we have a patient whose primary indication for going to the operating room is to have coronary bypass surgery or a valve replaced, but the patient also has atrial fibrillation, then the ablation is concomitant to the primary procedure,” Edgerton says.

According to Maze III, surgeons must open the atrium, which means it can be performed more easily when the atrium is already opened for another type of surgery, such as a mitral valve procedure.

“It’s right there in front of you and is relatively easy to do the rest of the Maze,” Edgerton says.

With concomitant operations, the surgeon is opening the atrium anyway, and an increasing amount of literature supports adding surgical ablation at that time, he says.

“Most of the studies we have are on concomitant ablation with an open atrium, and you can see that reflected in the guidelines,” Edgerton says. “The literature supporting this was excellent.”

This is why this particular category of concomitant surgery with open atrium received a Class I, Level A recommendation, meaning that it should be performed because there’s a strong benefit that outweighs the risk, and there is an “A” level of evidence to support that, he says.

  • Second category: Concomitant surgery with closed atrium also shows greater benefit than risk, Edgerton says.

Concomitant Afib ablation at the time of primary nonatriotomy operations includes patients who do not present with surgically significant intracardiac structural disease. These include patients who are undergoing aortic valve replacement (AVR) or coronary artery bypass grafting (CABG), or both.1

Surgical ablation concomitant with AVR or CABG is different from mitral procedures as the left atrium is closed, and so it requires more consideration of risk and surgical approach — whether the surgeon performs left and right atriotomies, or less invasive approaches such as epicardial surgical ablation procedures.1

Surgical ablation in the case of concomitant isolated AVR, isolated CABG, and AVR plus CABG operations to restore sinus rhythm can be performed without additional risk of operative mortality or major morbidity, the guidelines state.1

It’s a Class I, Level B, meaning it shows strong benefit and the evidence is of moderate quality.

“When you get into the weeds of studying the literature, the patients do better if you do the surgical ablation than if you don’t,” Edgerton says.

  • Third category: Stand-alone surgical ablation for Afib can be beneficial, depending on the circumstances.

“In stand-alone procedures, the only reason to go into the operating room is to do the Maze,” Edgerton says. “These situations require more reflection on the patient’s case. You shouldn’t just take a patient who has Afib and take him off to the operating room to fix it without making sure it couldn’t be fixed by easier, less risky means first.”

Patients who might need stand-alone surgical ablation might have failed drug therapy or have failed catheter ablation, he adds. “They have to fail a less risky procedure before it is reasonable for the surgeon to take the patient to the operating room.”

For instance, if the surgical ablation is for symptomatic Afib in the absence of structural heart disease that is refractory to class I/III antiarrhythmic drugs or catheter-based therapy, it is reasonable as a primary stand-alone procedure to restore sinus rhythm. In these cases, it is a Class IIA, Level B randomized, meaning it has moderate benefit versus risk, and the procedure can be useful and effective, and the evidence has moderate quality from one or more randomized, controlled trials or meta-analyses of moderate quality.1

Also, surgical ablation for symptomatic persistent or long-standing Afib in the absence of structural heart disease is reasonable as a stand-alone procedure, using the Cox-Maze III/IV lesion set. This one also is Class IIA, Level B nonrandomized.1

But in the case of symptomatic Afib in the setting of the left atrial enlargement or more than moderate mitral regurgitation by pulmonary vein isolation alone, it is not recommended and is a Class III, meaning it has no benefit, Level C expert opinion.1

The guidelines state that the primary indication for ablation in stand-alone patients is the presence of symptomatic Afib refractory to at least one class I or III antiarrhythmic drug.1

In the guidelines, STS also recommends that these surgical ablation decisions be made by a multidisciplinary heart team assessment with treatment planning and long-term follow-up of Afib patients.

Also, the guidelines’ authors say that when the ablation is conducted as a stand-alone procedure, there is evidence that surgeons should perform the full Cox lesion rather than a small part of it, Edgerton says.

Surgeons who follow the new STS guidelines will be more fully and adequately treating their patients and helping them better improve their outcomes, Edgerton says.

REFERENCE

  1. Badhwar V, Rank JS, Damiano RJ, et al. The Society of Thoracic Surgeons 2017 Clinical Practice Guidelines for the Surgical Treatment of Atrial Fibrillation; Special Report. Ann Thorac Surg 2017;103:329-341.