By Joshua D. Moss, MD

Associate Professor of Clinical Medicine, Cardiac Electrophysiology, Division of Cardiology, University of California, San Francisco

Dr. Moss reports no financial relationships relevant to this field of study.

SYNOPSIS: In patients with long-standing, persistent atrial fibrillation, outcomes with an electrophysiologically guided thoracoscopic surgical ablation procedure were superior to a standard catheter approach.

SOURCE: Haldar SK, Jones DG, Bahrami T, et al. Catheter ablation vs electrophysiologically guided thoracoscopic surgical ablation in long-standing persistent atrial fibrillation: The CASA-AF study. Heart Rhythm 2017;14:1596-1603.

Tools and techniques for catheter ablation of atrial fibrillation (AF) continue to improve, and the procedure consistently outperforms antiarrhythmic drug therapy across many populations. Results are best for patients with paroxysmal AF, in which episodes terminate spontaneously or with intervention within seven days of onset. In the 2017 HRS/EHRA/ECAS/APHRS/SOLAECE Consensus Statement, catheter ablation is a class I recommendation (Level of Evidence A) for treatment of symptomatic, paroxysmal AF in patients refractory to or intolerant of at least one antiarrhythmic medication and a class IIa recommendation prior to drug therapy. Long-standing, persistent AF (LSPAF, defined as continuous AF > 12 months’ duration) is substantially more difficult to control, and single-procedure success rates with catheter ablation often are well below 50%.

Thoracoscopic surgical ablation is a technique for partially reproducing the strategy of the effective open-heart Cox-Maze procedure, but in a less complex, less morbid, minimally invasive way. The authors of CASA-AF recruited 51 patients with LSPAF at one center in the United Kingdom, 25 of whom chose catheter ablation and 26 of whom chose surgical ablation. Relatively extensive catheter ablation was performed in all patients in the first group: pulmonary vein isolation (PVI), plus creation of left atrial roof and mitral isthmus lines, as well as ablation of left atrial complex fractionated electrograms and any sources of inducible atrial tachycardia. Patients in the surgical ablation group underwent bilateral thoracoscopic access, bilateral epicardial pulmonary vein isolation via a bipolar radiofrequency clamp, posterior wall isolation via superior and inferior lines, and ganglionated plexi ablation. In 13 patients, the left atrial appendage also was excluded and amputated. Post-procedure arrhythmia assessment was performed via seven-day continuous ambulatory monitoring at three, six, nine, and 12 months. If the decision was made to proceed with a second procedure for symptomatic recurrence after a three-month blanking period, then only catheter ablation was performed.

Single-procedure freedom from atrial arrhythmia while off antiarrhythmic drugs was significantly higher in the group undergoing surgical ablation (73% vs. 32%). Multi-procedure success off drugs also was higher (77% vs. 60%) but did not reach statistical significance. The incidence of major complications was higher in the surgical ablation group (27% vs. 8%; P = 0.07), but there was only one serious adverse event: intracerebral hemorrhage in a patient 60 days after catheter ablation, believed to be unrelated to the procedure. The authors concluded that in patients with LSPAF, an electrophysiologically guided thoracoscopic surgical ablation procedure was superior to the standard catheter approach.

COMMENTARY

This is not the first trial comparing catheter ablation with surgical ablation of AF: The authors of the multicenter FAST trial prospectively randomized 124 patients, most with paroxysmal AF and many with prior failed catheter ablation, and showed superior freedom from AF but significantly more adverse events via surgical ablation.1 However, the population in CASA-AF was exclusively patients with long-standing persistent AF in whom maintenance of durable sinus rhythm off antiarrhythmic drug therapy tends to be particularly difficult. The ability to demonstrate significantly superior AF suppression with thoracoscopic surgical ablation despite such a relatively small cohort is notable, although success rates were not significantly different after multiple procedures.

Patients were not randomized (the authors reported that the patients were given clinical information about both options “without bias”), but, ultimately, groups were fairly well-matched. Patients in the surgical group exhibited a statistically longer duration of continuous AF prior to ablation (a median of 24 months vs. 18 months in the catheter ablation group), although this might be expected to disadvantage surgical ablation, arguably making the actual outcomes that much more noteworthy.

Importantly, the authors introduced a meticulous technique for assuring the desired electrophysiological endpoints were achieved in the surgical ablation group beyond the routine testing performed with the surgical ablation tools. An electrophysiologist independent of the cardiac surgeon used a mobile EP mapping system and a multi-electrode catheter introduced through a thoracoscopic port to guide additional ablation in five of the 22 surgical patients tested. These findings suggest that the chances of long-term success with surgical ablation are improved significantly with formal electrophysiological testing during the procedure, as would be routine during catheter ablation. A major barrier to even minimally invasive surgical ablation remains its associated morbidity. Mean length of hospital stay was a week in the surgical ablation group. That was significantly longer than the 4.1-day hospital stay in the catheter ablation group, although it is unclear why hospitalizations were even that long. In routine clinical practice, 24-hour hospitalizations after catheter ablation are commonplace. Additionally, at least one major complication occurred in seven of the 26 surgical ablation patients, including four significant pulmonary vein stenoses. In contrast, the catheter ablation group had one asymptomatic pulmonary vein stenosis managed conservatively and one case of acute pulmonary edema soon after discharge. Minimally invasive surgical ablation may play an increasingly important role in the treatment of persistent AF, and cardiologists and their patients should be aware of this approach. Whether the associated risks are justified by the opportunity to avoid multiple catheter procedures to achieve comparable results will be a major question going forward. Further randomized trials are warranted (and ongoing), and a frank discussion of relative risks and benefits will be, as always, critical.

REFERENCE

  1. Boersma LV, Castella M, van Boven W, et al. Atrial fibrillation catheter ablation versus surgical ablation treatment (FAST): A 2-center randomized clinical trial. Circulation 2012;125:23-30.