An Effective Hybrid Ablation Procedure Performed Completely in the EP Lab

In the March 2014 issue of EP Lab Digest,¹ Jason S. Sperling, MD and Jonathan S. Steinberg, MD provided a review of a hybrid procedural approach performed completely in their EP lab. In this update, Dr. Steinberg discusses how the technique has evolved since then. 

In patients whose atrial fibrillation (AF) has become highly symptomatic, catheter ablation has become a potent therapy for the restoration and maintenance of normal sinus rhythm, and is recognized as an effective and safe alternative to chronic medical therapy. Indeed, randomized clinical trials provide testimony to the superiority of ablation compared to antiarrhythmic drugs, with much greater rates of complete AF suppression as well as an acceptable safety record.

The cornerstone strategy of ablation is based on the solid current understanding that most (but not all) AF is triggered from muscle fibers within the pulmonary veins (PVs), and hence, PV isolation (PVI) is the primary technical approach. PVI can achieve a complete response or substantially reduce the AF burden in many patients with AF. The best responses are typically seen in patients with normal or only mildly dilated left atria, and in patients whose AF is paroxysmal. While a single PVI treatment is successful in many such patients, repeat ablation procedures may be necessary in others who have experienced PV re-connection after an initial attempt or attempts at ablation. It is also well established that for patients in whom AF is persistent, standard catheter ablation is less likely to be successful. This has generated interest in more extensive ablation strategies to restore sinus rhythm. 

In many labs, when PVI is not successful (even in primary procedures), there are those who believe that much more extensive ablation can be beneficial. However, there are definitive data to refute this premise, and the most commonly used adjunctive procedures (such as complex fractionated atrial electrograms [CFAE] lesions, linear left atrial ablation) have not shown increment in efficacy. In addition, there is an important incidence of proarrhythmia resulting from these lesion sets, notably left atrial flutters, which can be difficult to manage medically and may necessitate repeated complex ablation for eradication. 

Focal Impulse and Rotor Modulation (FIRM), which had been promoted as a novel approach for all forms of AF, was associated with poor clinical outcomes in several observational series, and no benefit in a recent large-scale randomized clinical trial. Experience with left atrial appendage isolation, another strategy commonly advocated, suggests that stroke risk may increase even during chronic anticoagulant therapy.

Unfortunately, the need for repeat ablation procedures in the setting of AF is very troublesome to patients. The inconsistency, unpredictability, and breakthrough despite long periods of arrhythmia quiescence are frustrating to patients and clinicians alike. What is greatly needed and desired would be a reliable and predictable approach that could anticipate good success, even after prior ablation efforts. Unfortunately, short of major cardiac surgery, this goal has been elusive. 

Based on 7 years of clinical activity, we believe we now have an intervention that can provide reliability and reproducibility in the AF settings that currently present major therapeutic challenges. These include: (1) patients who have had 2 or more prior ablations but continue to experience AF with or without medical therapy; and (2) patients with longstanding persistent AF (for >1 year).

Our approach is based on the premise that AF substrate is critical once common triggers are eliminated by PVI. Although the exact mechanisms are not known, it is becoming evident that after the PVs, the next most important anatomic site that contributes to maintenance of AF is the posterior wall of the left atrium, the large region between the PVs (or pulmonary vein myocardium). The PVs and posterior wall are structures that have embryologically similar origins and similar electrophysiologic traits. The approach that we have implemented is differentiated from others in that we create a confluent posterior wall isolation not by outlining a perimeter, but instead by “coloring in” the box, an approach we believe may be more effective. In addition, our approach is facilitated by small subxiphoid access sites for the pericardial space, and is accomplished entirely in the electrophysiology laboratory, not in an operating room. In true collaborative spirit, a heart surgeon who specializes in AF uses a videoscope to enter the pericardial space (in the current iteration, no longer requiring transdiaphragmatic passage through the upper abdominal cavity) that leads directly to the posterior wall of the left atrium. A vacuum-assisted radiofrequency energy device is used to “color in” the accessible portions of the posterior wall, leading to a dense lesion set (Figure 1). The confluence of lesions achieved by direct epicardial ablation cannot be easily or consistently achieved with catheters on the endocardial surface, and the latter would also expose risky energy delivery to the esophagus. 

The second portion of the procedure is performed transvenously by members of our EP team, and is designed to complement the surgical portion. This may involve redo or primary PVI, or whatever is needed to eliminate existing organized atrial arrhythmias. Very critically, the posterior wall electrical activity is carefully mapped using high-density electroanatomic recordings. We have routinely found that this approach identifies minor, but genuine, residual connections to the body of the left atrium that were missed by the epicardial component of the procedure. As most of these reside at the superior edge of the posterior wall lesion set, and based on our analyses of individual patient anatomy, we believe that the anterior rotation of the left atrium and the adjacent pericardial reflection prevent the surgical ablation tool from reaching all desired aspects of the target zone. Hence, the endocardial consolidation of the lesion set is absolutely crucial.

The procedure has now been performed in a large series of patients at our lab. The hospital stay has generally been 2 nights, with a relatively rapid recovery. The complication rate has been very low. The procedure is reimbursed by insurance carriers. 

What has been most dramatic is the clinical response. The careful tracking of prospective outcomes in this series indicates that more than 70% of these patients have fully responded, eliminating all AF and need for antiarrhythmic drug therapy. The series includes patients with 2-5 prior ablation procedures and also those with longstanding persistent AF, making the results even more exceptional.

We thus believe we now have the “go to” procedure that we have long sought for patients who did not respond to initial ablation or have the most challenging substrate. The procedure is not excessively invasive, it has an excellent safety record, and is based on sound physiologic principles. It is now accomplishable because of optimized ablation tools, combined complementary endocardial and epicardial approaches, and successful hybridization of cardiac surgery and electrophysiology services. 

Disclosure: The authors have no conflicts of interest to report regarding the content herein. Outside the submitted work, Dr. Steinberg reports he is a consultant with AtriCure, Inc.  

1. Sperling JS, Steinberg JS. New Hope for Patients Who Have Failed Catheter Ablation: Effective Hybrid Procedure Performed Completely in the EP Lab. EP Lab Digest. March 2014. Available at https://www.hmpgloballearningnetwork.com/site/eplab/articles/New-Hope-Patients-Who-Have-Failed-Catheter-Ablation-Effective-Hybrid-Procedure-Performed-Co