The Convergent Atrial Fibrillation Ablation: The Emory Experience

Catheter ablation remains the cornerstone for the treatment of atrial fibrillation (AF). While success rates for paroxysmal AF remain high,¹ success rates for persistent AF remain suboptimal.² Despite technological improvement and refinement in understanding for fibrillatory mechanisms, treatment of persistent AF beyond pulmonary isolation remains elusive.

Persistent AF represents a heterogenous population with unclear mechanisms of AF initiation and maintenance. Within this population, there is considerable variability in left atrial scar burden or fibrosis,³ left atrial enlargement, AF triggers, drivers,⁴ and medical comorbidities. Implications of ablation target vary among this population, which might explain variable outcomes. An individualized treatment strategy is necessary given the spectrum of disease pathology.

Targets beyond the pulmonary veins have been recently studied given their implications in arrhythmogenesis. For instance, the posterior wall has recently gained traction as a critical part of AF treatment. This is suggested by its complex tissue architecture and fibrosis, leading to initiation and maintenance of AF.⁵ While previous studies proved promising,^6,7 others have not.⁸ Beyond its implication in AF, there are significant technical challenges, such as epicardial connections⁹ and proximity to the esophagus, leading to the risk of atrioesophageal fistula formation. This leads to incomplete posterior wall isolation and subsequent reconnection,¹⁰ leading to recurrence or proarrhythmia. Other targets, such as isolation of the left atrial appendage, have shown to improve outcomes in persistent AF,¹¹ but carry a significantly elevated risk of lifelong thromboembolic strokes.¹²

Recently, surgical therapy for persistent AF has become an increasingly utilized strategy for patients with persistent AF. Surgical ablation allows targeting of structures that are limited by endocardial ablation due to lack of durable lesion sets or concern for complications. Various types of surgical strategies make it difficult to compare among procedures, given reported success rates varying from 65-85% among centers. At Emory University, our approach to surgical treatment of persistent AF has been the convergent procedure, which consists of both a surgical and endovascular approach for the treatment of persistent AF. We have performed over 200 convergent procedures over the past several years. The surgical approach is via subxiphoid access, where the surgeon aims to isolate the posterior wall. Next, the endovascular approach is utilized to ensure all surgically targeted structures are ablated and allows for touch-up lesions to ensure durable isolation. In our vast experience, performing a roof line frequently results in complete posterior wall isolation. At our institution, this is done as a same-day procedure, with discharge in 2-3 days. More recently, we incorporated clipping the left atrial appendage during the surgical approach for both rhythm control and stroke prevention.

Emory was a major contributor to the CONVERGE trial,¹³ which randomized 153 patients with persistent AF in a 2:1 fashion to hybrid convergent surgery versus catheter ablation, achieving AF freedom of 67.7% in the convergent arm. David DeLurgio, an Emory electrophysiologist, was the national PI on this trial. Our experience demonstrated that patients (n=113) who underwent hybrid convergent strategy had 53% freedom from AF. Of the patients that had recurrence, 94% of the cohort was free from an arrhythmia burden greater than 5%.

Prior to recommendation, each patient undergoes a thorough evaluation by the electrophysiologist and the cardiac surgeon. Coordination among team members is carried through a designated navigator to facilitate appropriate evaluation and care. During each consultation, both the electrophysiologist and patient undergo a shared decision making process, including the pathophysiology of AF, the various treatment options, and our institutional success rate. Consideration of the convergent procedure is based on patient characteristics, such as previously failed cardiac ablation, large left atrium (LA diameter >5 cm), and need for left atrial clipping (Figure 1).

We present a 65-year-old male with a history of hypertrophic cardiomyopathy and 3-year history of persistent AF with a left atrial diameter of 5.4 cm. Despite multiple cardioversions and antiarrhythmic therapy, the patient remained in symptomatic AF, which had significantly limited his quality of life. Given his history, we proceeded with a convergent procedure with the same-day strategy of surgical and endovascular procedure.

The patient underwent surgical ablation of the posterior wall and left atrial appendage clipping. Afterwards, the patient underwent catheter ablation. Figure 2A shows a posterior anterior projecion of the left atrium after surgical ablation. Regions of healthy atrial tissue (purple) are seen in the left atrium, while areas of scar (gray) are located along the posterior wall and inferior right and left pulmonary veins. Ablation of the roof and pulmonary veins was performed, which allowed the entire posterior wall and 4 pulmonary veins to become electrically isolated, thus preventing a large amount of the atrium from sustaining AF. Furthermore, other portions of the left atrium are left viable. Over the last 3 years since her ablation, the patient has remained free of AF.

Next, we present a 73-year-old male with paroxysmal AF that progressed to persistent AF despite 2 previous AF ablation procecdures and multiple antiarrhythmics and cardioversions. Echocardiogram revealed normal ejection fraction and mildly dilated left atrium (LA diameter 4.7 cm). Given his previously unsuccessful ablation, a hybrid convergent surgical approach was chosen.

Figure 3A shows the left atrial map after surgical ablation using the Orion mapping catheter (Boston Scientific). There is a small area of low-voltage regions in the posterior wall, while the rest of the pulmonary veins are isolated. Ablation lesions at the posterior wall left this completely isolated (Figure 3B). At 8-month follow-up, he has not sustained any further atrial arrhythmias.

The hybrid convergent procedure is a novel technique utilizing both a surgical and endovascular approach to deliver effective and safe treatment for persistent and longstanding persistent AF. This approach allows for individualized treatment in patients with advanced substrate for AF. Our experience in utilizing this novel approach has resulted in improved freedom from AF and arrhythmia burden in patients with difficult to treat AF. This approach requires careful planning along with coordination among arrhythmia team members, and has optimized clinical outcomes.

Disclosure: The authors have no conflicts of interest to report regarding the content herein. Outside the submitted work, Dr. El-Chami reports he is a consultant for Medtronic, Boston Scientific, and BIOTRONIK.