A 48-year-old male with highly symptomatic persistent atrial fibrillation (AF) was seen in consultation. He was an amateur hockey player who had undergone three previous ablations for AF (including pulmonary vein isolation and left atrial rotor mapping/ablation) since 2008. Each procedure was associated with a temporary respite from recurrent AF, but the AF always recurred, associated with a decline in quality of life.
Hybrid ablation was suggested and accomplished smoothly. Since the procedure over 18 months ago, this patient has had no recurrence of AF, and is extremely satisfied with an improved quality of life. He has resumed playing ice hockey.
In patients whose AF has become highly symptomatic with a negatively impacted quality of life, catheter ablation has emerged as a potent therapy in the restoration and maintenance of normal sinus rhythm. It 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 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. 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, or even at primary procedures, there are those who believe that much more extensive ablation can be beneficial. As of now, there is no definitive data to support or refute this claim. There is no question that there is some incremental benefit in AF reduction by these additional efforts, but there can be greater procedural complications and a very important incidence of proarrhythmia resulting from these lesion sets, particularly left atrial flutters. These are often very difficult to manage medically and may necessitate repeated complex ablation for eradication, with higher than desired failure and recurrence rates.
Unfortunately, the need to 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 “go to” approach that could reliably predict very high final success, even after prior ablation efforts. Unfortunately, short of major cardiac surgery, this goal was elusive. We have sought such an approach for our own patients, as well as the many patients who have been treated elsewhere and have expressed an interest.
Based on two years of clinical activity, we believe we now have an intervention that can provide very high reliability and reproducibility in the AF settings that currently present major therapeutic challenges. These include: (1) patients who have had 1-2 or more prior ablations but continue to experience AF with or without medical therapy, and (2) longstanding persistent AF (AF for >1 year).
Our approach is based on the premise that AF substrate is critical once common triggers are eliminated by PVI. Though the exact mechanisms are not known, it is becoming obvious that after the PVs, the next most important anatomic site that contributes to AF is the posterior wall of the left atrium, between the PVs. The PVs and posterior wall are structures that derive together embryologically, so the importance of the posterior wall is not surprising. One of the primary reasons that the classical ‘cut and sew’ Maze procedure was historically so effective was the surgical isolation of both the posterior wall of the left atrium as well as the PVs (called the ‘box lesion’). Other surgical approaches have been proposed to carry out the box lesion in a minimally invasive fashion using radiofrequency, microwave and ultrasound. All of these involve approaches through the chest or ribs, and none have been consistently effective. A big part of the problem with creation of a box lesion is that if any part of the perimeter of the box does not maintain a transmural contiguous lesion, the whole box is ruined. The approach that we have developed is differentiated from others in that we create our box not by outlining a perimeter, but instead we ‘color in’ the box, an approach we believe may be more effective. In addition, our confluent posterior left atrial ablation is accomplished without going through the chest or ribs, and is done in the electrophysiology laboratory, not in an operating room. In true collaborative spirit, a heart surgeon who specializes in AF uses a videoscope to go through the abdomen (like a laparoscopic gallbladder procedure) to get across the lower portion of the diaphragm, beyond which 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 an extensive lesion set (Figure 1). The confluence of lesions achieved by direct epicardial ablation cannot be achieved with catheters on the endocardial surface, and the latter would also expose risky energy delivery to the esophagus. In over 30 cases, we have not experienced any major complications. Of course, posterior wall ablation alone is likely to be ineffective if the PVs have not been isolated.
The second portion of the procedure is performed transvenously by members of our EP group and is designed to complement the surgical portion. This may involve redo or primary PVI, mapping of left atrial flutters, Focal Impulse and Rotor Modulation (FIRM), or whatever is needed to eliminate existing atrial arrhythmias. The absence of posterior wall electrical activity is confirmed as well, which has been the norm.
The procedure has now been performed in a large series of patients at our institute. The hospital stay has generally been two 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 well above 90% of these patients have fully responded, eliminating all AF and the need for antiarrhythmic drug therapy. The series includes patients with 1-5 prior ablation procedures and also those with longstanding persistent AF, making the results even more exceptional.
We 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 (e.g., longstanding persistent AF). The procedure is not excessively invasive, has an excellent safety record, and is based on sound physiologic principles. It is now accomplishable because of optimized ablation tools and combined complementary endocardial and epicardial approaches, as well as successful hybridization of cardiac surgery and electrophysiology services.
Disclosure: The authors have no conflicts of interest to report regarding the content herein.