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Persistent Atrial Fibrillation With Successful Convergent Ablation
EP LAB DIGEST. 2023;23(4):21-23.
Atrial fibrillation (AF) is the most common cardiac arrhythmia managed in clinical practice, affecting approximately 33.5 million people.1 AF is characterized by rapid, disorganized excitation of the atria that leads to an increased risk for cerebrovascular events, tachycardia-mediated cardiomyopathy, dementia, and mortality.2 There are 4 pillars of treatment for AF: anticoagulation for thromboembolic prevention, rate control, rhythm control, and lifestyle changes. The decision for rhythm control is shared between the patient and provider, with rhythm strategies consisting of direct current cardioversion (DCCV), antiarrhythmic drugs (AAD), and varying ablative techniques.
Pulmonary vein isolation (PVI) through catheter ablation is considered one of the most effective treatment strategies for paroxysmal AF. In contrast, PVI for persistent AF (PsAF) has demonstrated suboptimal success rates, particularly with long-standing persistent AF. This is thought to be due to PsAF having multiple extrapulmonary vein drivers and substrates involving the posterior wall (PW), including focal ectopic triggers, rotors, and complex fractionated atrial electrograms. It is challenging to add additional lesions to PVI through catheter ablation to address these drivers and substrates, which led to hybrid convergent ablation. Following the CONVERGE trial in 2020, convergent ablation showed superior effectiveness compared to catheter ablation for the treatment of PsAF.3
Briefly, convergent ablation combines minimally invasive endoscopic surgical epicardial ablation with endocardial catheter ablation in 2 separate stages.3 This has the benefit of reducing the risk of esophageal and phrenic nerve injury, and allows direct left atrium (LA) visualization while being less invasive than the Cox-maze procedure.3,4 The epicardial ablation stage can be performed via a small incision without the need for sternotomy or cardiopulmonary bypass. This stage also allows for the targeting of epicardial fat and ganglionic plexi, which may be helping to sustain PsAF.4
A tailored, patient-centered approach is required to identify the underlying mechanism of PsAF. Presented here is an interesting case of PsAF and the successful restoration of sinus rhythm with convergent ablation.
Case Presentation
A 70-year-old man with a well-known history of long-standing PsAF presented to the clinic. In 2015, the patient was diagnosed with AF after he presented to his primary care provider with a sore throat and was ultimately found to be in AF on electrocardiogram (ECG). This led to a referral to our practice. The patient was asymptomatic and was started on metoprolol for rate control. At the time, he had a CHADS2 score of 1 for hypertension. Anticoagulation was recommended, but the patient ultimately declined. In 2016, the patient began oral anticoagulation with apixaban. The patient remained asymptomatic in PsAF until 2019, when he presented with a decrease in exercise tolerance. An echocardiogram revealed no evidence of LA enlargement. Because he had been in AF for 4 years, a hybrid convergent ablation was discussed with the patient. He opted to consider the decision further and report back at a later time. He progressively became more symptomatic with PsAF and was seen by our cardiothoracic (CT) surgeon in 2020. The patient remained hesitant to move forward with the procedure until February 2022, when he was ready to proceed. He was reevaluated by our CT surgeon in April 2022. Forty-eight hours prior to the procedure, he was scheduled for preoperative studies, including a computed tomography angiography of the chest and a transesophageal echocardiogram (TEE).
The patient underwent the epicardial component of his hybrid convergent ablation in May 2022. The patient was brought to the operating room (OR) and placed under general anesthesia. A TEE was performed that showed no evidence of LA thrombus. A subxiphoid pericardial window approach was used. A series of 15 lesions were created between the left and right PVs and the pericardial reflection. Next, 2 lesions were created on the right atrial free wall and 2 lesions were created in the coronary sinus (CS) area. Subsequently, a left atrial appendage (LAA) clip was applied, with proper positioning shown by TEE. Then, the ligament of Marshall (LOM) was completely divided. Finally, successful DCCV at 200J was performed and the patient left the OR in normal sinus rhythm.
On postoperative day one, he developed bradycardia into the 30s complicated by syncope. The patient converted back into AF. He was started on amiodarone and had a repeat electrical cardioversion. This was initially successful; however, the patient then developed significant bradycardia/junctional rhythm requiring atropine. The patient subsequently developed atrial flutter (AFL). Prior to discharge, the patient received a dual-chamber pacemaker. Upon discharge, the patient was restarted on amiodarone and metoprolol, with the second stage of hybrid convergent ablation scheduled in 6 weeks.
The patient underwent the endocardial component of his hybrid convergent ablation in July 2022. He was brought into the electrophysiology lab and placed under general anesthesia. A TEE was performed that revealed adequate occlusion of the LAA with no thrombus. While pacing the LA from the CS decapolar catheter, a 3-dimensional (3D) geometric shell and electroanatomic voltage map using the Carto system (Biosense Webster, Inc, a Johnson & Johnson company) was created with the decapolar mapping and ablation catheter involving the LA, PVs, and LAA.
Ablation lesions were delivered sequentially in a point-by-point fashion at 50 W with a goal ablation index of 400 on the PW and 500 on the anterior wall until LA-PV disconnection was achieved. A right antral ablation was performed by coming up the anterior wall and then connecting to the roof. This was then repeated for the left by coming up the coumadin ridge on the LAA side to complete the circumferential lesion set around the left veins. The PW was silent with the exception of some small signal in the upper PW. This area was ablated at the end of the case to eliminate all signals and PW isolation was confirmed with high-output pacing at all points.
Three different AFLs were seen and ablated during the procedure. The first was roof-dependent flutter rotating around the left superior PV through the carina of the left veins. The second was mitral flutter, which was ablated with an anterior mitral line (Videos 1 and 2). The third was cavotricuspid isthmus (CTI)-dependent flutter with a CTI line. Additionally, there were some fractionated signals in the Marshall bundle area at the base of the appendage inferiorly, so theses were ablated as well.
Video 1
Video 1. Mitral flutter.
Video 2
Video 2. Postprocedural voltage map with the final lesion set.
The patient was seen in the clinic for follow-up in August 2022 and November 2022. At both visits, the patient had no AF recurrence post ablation. At the November visit, apixaban and amiodarone were discontinued, with 1-year follow-up planned for July 2023.
Discussion
This case illustrates the successful ablation of long-standing PsAF (>5 years) with convergent ablation. The case highlights the complexity of ablation in patients with long-standing PsAF given the need to map and ablate 3 different AFLs, as well as the benefit of additional substrate ablation beyond PVI including PW isolation, LAA clipping/ablation, and interruption in the LOM. The combined epicardial and endocardial approach allows for more complete ablation of the AF substrate as well as non-PV triggers.
Following the ablation, the patient has remained without recurrence, as documented on his most recent device interrogation in December 2022 (Figure). He was on AAD therapy with amiodarone, which was discontinued 4 months postablation at a follow-up office visit due to no recurrence. If the patient experiences notable recurrent AF, repeat ablation vs AAD will be considered. Thus far, the results of this case have supported the results of the CONVERGE trial with significant reduction in AF burden. The patient will be monitored for recurrence of AF with device interrogations every 3 months, and is scheduled for follow-up at 1-year postablation.
Regarding safety concerns with this procedure, following the results of the CONVERGE trial, 2.9% (3/102 patients) reported events within 7 days postprocedure and 5.9% (5/102 patients) reported events after day 7 through 30 days.3 The primary safety rate was driven by late pericardial effusion, given the delayed inflammatory response to pericardiotomy and ablation. In the case, the patient experienced severe bradycardia following the epicardial stage, resulting in pacemaker implantation. However, despite pacemaker placement, the patient experienced a significant improvement in his exercise capacity and quality of life.
Conclusion
The addition of the epicardial ablation with this hybrid process results in reduced endocardial ablation time and improved efficacy with transmural and durable lesions. This innovative procedure allows for increased freedom from AF, as well as the benefit of decreased procedural risks to the periesophageal branches of the vagus nerve or atrioesophageal fistula.3-5 The addition of surgical division of the LOM and clipping/ablation of the LAA targets substrate and triggers that are difficult to manage with endocardial ablation alone. For patients with long-standing PsAF, this remains our procedure of choice.
Along with the high-quality evidence from the CONVERGE trial, we hope this case demonstrates an example of the efficacy and supports transmural PW ablation, in addition to PVI, as an ideal strategy for treating advanced AF.3
Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. They have no conflicts of interest to report regarding the content herein.
References
1. Li J, Gao M, Zhang M, et al. Treatment of atrial fibrillation: a comprehensive review and practice guide. Cardiovasc J Afr. 2020;31(3):153-158. doi:10.5830/CVJA-2019-064
2. Westerman S, Wenger N. Gender differences in atrial fibrillation: a review of epidemiology, management, and outcomes. Curr Cardiol Rev. 2019;15(2):136-144. doi:10.2174/1573403X15666181205110624
3. DeLurgio DB, Ferguson E, Gill J, et al. Convergence of epicardial and endocardial RF ablation for the treatment of symptomatic persistent AF (CONVERGE trial): rationale and design. Am Heart J. 2020;224:182-191. doi:10.1016/j.ahj.2020.02.016
4. Mannakkara NN, Porter B, Child N, et al. Convergent ablation for persistent atrial fibrillation: outcomes from a single-centre real-world experience. Eur J Cardiothorac Surg. 2022;63(1):ezac515. doi:10.1093/ejcts/ezac515
5. Wats K, Kiser A, Makati K, et al. The convergent atrial fibrillation ablation procedure: evolution of a multidisciplinary approach to atrial fibrillation management. Arrhythm Electrophysiol Rev. 2020;9(2):88-96. doi:10.15420/aer.2019.20
