Convergent Hybrid Ablation

Disclosure: The author of this video is a consultant and proctor for Atricure—the company that makes the Epi-Sense catheter used in this procedure.

This video focuses on the convergent hybrid ablation procedure, which recently received FDA approval for the treatment of longstanding persistent atrial fibrillation (AF). It covers the rationale for the procedure, the surgical components that make up the procedure, as well as existing related data.

Rationale for the Procedure

AF infection affects 33,000,000 people worldwide. Seventy percent of these patients have persistent or longstanding persistent AF. As a group, patients with persistent or longstanding persistent AF are more difficult to treat. Pulmonary vein isolation has been shown to be an effective treatment of paroxysmal AF; however, outcomes for this treatment in patients with persistent and longstanding persistent AF are not as good. Several studies of patients with persistent and longstanding persistent AF treated with catheter ablation have shown successful outcomes in the one- year range from 35 to 50 percent, and those outcomes often require several procedures to obtain.

As opposed to paroxysmal AF, where triggers come from the pulmonary veins in persistent and longstanding persistent AF, the triggers and drivers often come from elsewhere, most commonly the posterior left atrial wall. The posterior left atrial wall has the highest portion of non-pulmonary vein triggers. It is also the most common site of reentrant AF drivers.

Achieving transmural lesions on the posterior wall with an endocardial approach is challenging for a couple of reasons:

1. There can exist an endo- and epicardial dissociation
2. Because endocardial energy is directed posteriorly (i.e., toward the esophagus) the amount of energy that can be delivered is limited

Additionally, an endocardial approach normally involves treatment with a box lesion from a small catheter with high rates of lesion failure. The convergent hybrid ablation procedure combines both endo- and epicardial ablation to isolate both the pulmonary veins and the posterior wall. The epicardial ablation is performed by the surgeon using the Epi-Sense (EP) catheter with energy directed toward the heart and away from the esophagus. EP will map the left atrium, complete the pulmonary vein isolation, and touch up were needed. The map in this video shows a completed lesion set that covers the posterior wall, along with the pulmonary veins. This posterior wall ablation does not rely upon one line only.

Surgical components

The convergent hybrid ablation procedure begins with a small incision just below the xiphoid process. The incision is carried down to the xiphoid itself, the xiphoid is grasped with a Kocher clamp, and the surrounding tissues are dissected away. A rongeur is then used to remove the xiphoid itself. The incision is continued down to the pericardium. The pericardium is then opened. Once in the pericardial space, a trochar is inserted into the posterior pericardium.

Next, the camera is inserted, and the anatomic landmarks—the IVC, the right inferior and superior pulmonary veins, and the left pulmonary veins—are identified. As is often the case when the trochar is first inserted, it abuts the right ventricle, requiring some readjustment. We first identify the IVC, and then turn the phalange posteriorly, come along the posterior pericardium, and insert the trocar. We then identify the coronary sinus. Next, we identify the right pulmonary veins with adhesions. To the left will be the left pulmonary veins. These are often one anatomic structure at this point.

Once those landmarks are identified, the Epi-Sense catheter is inserted and the ablation is performed. We move as cephalad and as far right as possible The display will show the impedance and power delivered over time. It is typical to make two rows of ablation and cover the posterior left atrial wall moving from right to left. For the first row, we make continuous ablation lines moving from right to left. W e complete the second row in a similar fashion. When completed, inspect the posterior wall, which will show the homogeneous nature of the ablation lines completely covering the left posterior atrial wall. The trochar is now removed, and a Blake drain is inserted. The fascia is then closed with Ethibond interrupted braided suture.

Existing Data

The Converge study was a multicenter prospective randomized study comparing the convergent procedure with standalone catheter ablation. Sixteen US sites and two sites outside the US participated, contributing 153 patients with follow-up of up to twelve months, eighteen months, and annually out to five years. The results of the trial showed that hybrid ablation was superior to catheter ablation at twelve months when stratified for patients off antiarrhythmics, absent new or increased doses of previously failed antiarrhythmics and irrespective of antiarrhythmic use.

This difference continued out to eighteen months, again showing hybrid convergent to be superior both in terms of AF burden reduction, as well as overall freedom from AF with a 20-point absolute difference. Even more pronounced were the differences in the cohort of patients with longstanding persistent AF. At both twelve and eighteen months of convergent hybrid ablation, patients faired significantly better than those receiving catheter ablation alone. This was true when specifically looking at overall freedom from AF, flutter, tachycardia, as well as AF burden reduction.

These conclusions were corroborated with real-world data showing significant benefit to hybrid ablation versus catheter ablation. There was a single-center study of forty-three consecutive patients with longstanding persistent AF treated with hybrid ablation matched with historical catheter ablation controls. Patients in the hybrid ablation arm faired significantly better at twelve and thirty months. Another study by Makati et al., looked at using endocardial cryoablation for pulmonary vein isolation and the hybrid procedure as opposed to RF ablation. They demonstrated freedom from AF of 85 percent at almost fifteen months in patients with persistent AF, and 70 percent at almost seventeen months in patients with longstanding persistent AF.

Results of the Converge trial along with other real-world data led the FDA to approve the Epi-Sense system for the treatment of longstanding persistent AF. The Converge trial demonstrates that a hybrid epicardial and endocardial ablation approach has superior effectiveness compared with endocardial-only ablation. Hybrid ablation is effective and should be considered in patients with persistent and longstanding persistent AF

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