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Modern Ablation Therapies for Atrial Fibrillation: The “Staged” Hybrid Approach
Background
Atrial fibrillation (AF) is a chronic condition. For many patients, rate control is not enough, so more aggressive rhythm control strategies are necessary. This is our core competency. For many symptomatic patients, catheter ablation is recommended as the most effective rhythm-stabilizing therapeutic option. Thus, depending on the situation, an invasive strategy may be possible before initiation of medication if offered at an experienced ablation center. In general, studies show that catheter ablation is more effective than drugs for recurrence prophylaxis in rhythm-stabilizing therapy of AF.
But catheter ablation also has its limits, and redo procedures are often necessary to achieve sufficient symptom relief and rate control. Fragmented care for AF patients poses a big problem as well, as EPs and surgeons are sometimes not used to working together on these complex AF patients, and indications are very seldomly posed together.
In this article, we review modern hybrid therapies for the treatment of atrial fibrillation. We discuss our hybrid approach at the Heart and Rhythm Center, with the focus on patient selection and different approaches to treating these challenging cases. In our opinion, a Heart Team or multidisciplinary team is not necessary in 95% of cases, and only select cases mandate this approach. The following clinical scenarios are the ones under our special focus: redo cases after 2 or 3 failed catheter ablation procedures, patients not amenable to catheter ablation procedures, and special indications such as patients benefitting from the cessation of oral anticoagulation (ie, after left atrial appendage [LAA] closure). As hybrid treatments become more and more attractive, we make the case for our staged hybrid approach.
Current Treatment Strategies for Atrial Fibrillation
Rate Control
In this treatment strategy, AF is accepted as permanent, and drugs and devices are used to stabilize the heart rate. If that is not possible, a pacemaker can be implanted, and in a second stage, the atrioventricular (AV) node can be modulated to achieve perfect rate control — this is called a “pace and ablate” strategy. This should only be considered once all other therapeutic options have been explored, including surgery for AF.
Rhythm Control
The rhythm control approach refers to the use of medications, cardioversion, ablation, and/or surgery to get the heart back into and to maintain normal sinus rhythm.
In catheter ablation of atrial fibrillation, pulmonary vein isolation (PVI) is the primary endpoint. Cryoablation is our method of choice for first-time procedures. In the redo setting, PVs are checked and lesions are completed using radiofrequency and advanced 3D mapping. Additional lesions are applied when warranted. Ablation of atypical atrial flutter is one principal indication for redo procedures after surgical ablation. Advantages of catheter ablation include the availability of advanced mapping (Figures 1 and 2), reliable PVI (especially with the cryoballoon), and use of a percutaneous endocardial approach. One major limitation is the lack of lesion transmurality in anatomically critical regions.
Surgical ablation, mainly performed thoracoscopically, is a minimally invasive surgical procedure executed by cardiac surgeons. The procedure is accomplished with the patient under general anesthesia. A camera and instruments are inserted through small incisions on the chest wall, and then the same ablations are performed on the epicardial surface of the heart. This is an anatomical procedure during which PVI and a complete isolation of the posterior left atrium are performed, and the left atrial appendage is safely and effectively occluded. For LAA occlusion, we use either the AtriClip device (AtriCure, Inc.)1 or a stapler. Endpoints are documentation of epicardial entrance and exit block of both PVs and the posterior wall box, in addition to transesophageal echocardiographic (TEE)-assisted closure of the LAA. Advantages of surgical ablation are effective ablation and LAA occlusion. Limitations are that the procedure is invasive, no mapping is performed, and it is only performed on the epicardial surface of the atrium (Table 1, Figure 3).
Heart Team Approach – Hybrid Strategies
Collaboration between an electrophysiologist and a specialized cardiac surgeon offers a significant expansion of the treatment options for patients with complex AF. This is a new and innovative alliance based on a therapeutic hybrid approach. For patients with complex forms of AF, a hybrid strategy combines the best of surgery by offering epicardial targets for focused ablation and LAA occlusion and EP procedures, allowing for 3D mapping and endocardial ablation in places not amenable to surgery.
A catheter-first approach is more frequently used. Paroxysmal AF can be eliminated in over 90% of cases after one or two procedures, depending on the type of AF and patient conditions. When additional risk factors (eg, long duration of AF, enlarged AF, hypertension, etc.) are present such that the outcome may be suboptimal, a surgery-first approach can be implemented according to the guidelines.2
A surgery-first strategy is often limited to cases of long-standing persistent AF. Strictly oriented to anatomical structures, the surgeon attempts to isolate the posterior left atrium, including the pulmonary veins, and performs LAA occlusion to eliminate the need for anticoagulation after the procedure. In the few cases in which a cardiac arrhythmia recurs after rhythm surgery, the electrophysiologist will utilize 3D mapping and ablation to reassess the situation and, if necessary, “re-treat” (in rare cases of PV/box reconnection) or eliminate the arrhythmia (extrapulmonary triggers).
A hybrid approach as proposed by Gelsomino and La Meir is composed of simultaneous endocardial and epicardial techniques in one clinical setting on the same day.3 In our opinion, this does not allow effects of one or the other treatment strategy to develop completely. We believe in staggering the procedures to better understand the effect of each approach and then not only complete the lesion set, but also verify PV isolation and lines of block, and possibly do some touchup when necessary. This allows us to potentiate the procedural outcome.
At the Heart and Rhythm Center, this consists of up to 2 interventions. Whether surgical or non-surgical intervention is performed first depends on the individual situation. Often, the originally planned second interventions are no longer necessary. Our outpatient clinic generates the patient flow. Patients are addressed by specialists, GPs, or self-referral after initial triage. It is approximately 70% to 30% for catheter vs surgical ablation for these selected patients. Similar to the recently published long-term follow-up of the FAST trial,4 a significant number of patients cross over to the other treatment group. About 40% go from catheter to surgical ablation, and 10% vice versa — in line with the most recent data.5
Both measures are basic components of AF therapy and result in a high degree of freedom from AF, but also freedom from symptoms and freedom from medications such as oral anticoagulants when the left atrial appendage is surgically eliminated. Recent studies show that combining both procedures can significantly improve outcomes for rhythm control in these complex patients.6
Case Presentation
A 67-year-old female with long-standing persistent AF (CHA2DS2-VASc score 2, EHRA 3, and symptoms for 8 years) presented as a self-referral from abroad. She had heard about the Heart and Rhythm Center from a friend. Her cardiologist in Spain had told her she should live with the atrial fibrillation and continue with blood thinners. Due to chronic fatigue and shortness of breath, she wanted a second opinion and traveled to Switzerland for a further workup. She had hip surgery 15 years ago and has experienced atrial fibrillation ever since. For 4 weeks, she has complained of increased dyspnea on exertion and more frequent palpitations at night. A cardiac workup revealed a structurally normal heart, with only a dilated left atrium (55 mm transversal diameter) on transthoracic echocardiography. A 21-day Holter demonstrated continuous atrial fibrillation with good frequency control. Coronary CT showed a very low coronary calcium score. Stress ECG was normal. We interpreted her symptoms as coming from the atrial fibrillation and suggested the following treatment regimens: (1) Rate control with medications and attempted symptom control; or (2) Rhythm control with a hybrid ablation procedure (staged).
To move forward, we decided to first do a DC cardioversion with amiodarone support to assess whether symptomatic relief would be experienced. Indeed, the patient felt much better after 2 weeks. Thus, she wanted to plan the rhythm control strategy as soon as possible. After complete workup, we performed the surgical ablation procedure. This was composed of complete posterior box isolation including bilateral pulmonary vein isolation with a bipolar ablation device. Finally, the left atrial appendage was resected with a stapler device. At the end of the procedure, we documented bidirectional pulmonary vein isolation with epicardial measurements (Cardioblate MAPS Device, Medtronic) as well as complete isolation of the posterior left atrium. The procedure lasted 70 minutes, and the patient went home on day 4. After 4 weeks, a sudden onset of an atypical atrial flutter was treated by DC cardioversion. When this returned after 2 more weeks, the patient wanted to undergo the second step of the procedure. During this procedure, complete isolation of the pulmonary veins was demonstrated. An atrial tachycardia (AT)originating from the superior posterolateral aspect of the right atrium was induced, precisely mapped using CARTO (Biosense Webster, Inc., a Johnson & Johnson company), and successfully ablated.
At 12-month follow-up, there was no AF or AT on a 3-week Holter ECG. She was no longer experiencing symptoms and was off medications.
Discussion
While there are several ways to perform a hybrid procedure, we advocate for a “staged” hybrid concept, meaning that electrophysiological and surgical interventions are performed separately and only when necessary. This has led to an avoidance of needless ablations and has also increased long-term safety for patients without reducing effectiveness. The focus is on treating the patient as effectively and as noninvasively as possible. We believe this approach helps patients become more amenable to rhythm control who might not have been candidates before.
Great attention is focused on careful patient selection and multidisciplinary discussion of an individual, patient-centered approach. The core of our Heart Team consists of an interventional EP specialist and a cardiac “rhythm” surgeon, and closely involving referring physicians, cardiologists, and other medical specialists.
