Atrial Fibrillation and Heart Failure: Utilization of Hybrid Ablation Therapy to Improve Patient Outcomes

Case Vignette

A 62-year-old male with a history of long-standing persistent atrial fibrillation (AF), coronary artery disease (CAD) with myocardial infarction status post percutaneous coronary intervention in 2020, hypertension, combined diastolic and systolic heart failure, diabetes mellitus, chronic kidney disease, dyslipidemia, and obstructive sleep apnea treated with continuous positive airway pressure presented to the AF clinic with a 2-year history of rate-controlled AF on metoprolol. He began having more progressive dyspnea and demonstrated a decline in his previously normal ejection fraction (EF) to 40% on echocardiography. He was also noted to have moderate to severe left atrial (LA) enlargement, with a LA volume of 100 mL/cm². After exclusion for other causes of left ventricular dysfunction, including ischemic workup by nuclear stress test, he was placed on amiodarone and referred for hybrid AF ablation. Given the persistent nature of his AF, the decline in his EF, and his severe LA enlargement, it was felt that proceeding with catheter ablation alone would not yield a high chance of success at long-term reduction in AF burden.

In May 2021, he completed the first stage of hybrid AF ablation, including epicardial posterior LA wall ablation, dissection of the ligament of Marshall (LOM), and left atrial appendage (LAA) exclusion with an AtriClip Pro-V Device (AtriCure). As he was previously ablation naive, he remained in persistent AF between the stages and was continued on amiodarone. In July 2021, he completed the second stage of hybrid AF ablation, including endocardial pulmonary vein isolation (PVI), LA roof line ablation, and cavotricuspid isthmus (CTI) ablation. Figure 1 illustrates the voltage map of the LA posterior wall pre- and postablation.

After completion of the second stage, he presented to the office for 6-week follow-up in normal sinus rhythm with marked improvement in functional tolerance and resolution of his dyspnea. He was taken off amiodarone and has continued to maintain normal sinus rhythm at 6-month follow-up from the last procedure. Follow-up echocardiogram has shown normalization of his EF.

Challenges of Catheter Ablation

Since the landmark trial by Haïssaguerre et al¹ in 1998 demonstrating the PVs to be a primary trigger for the initiation of AF, catheter ablation for AF has moved into the mainstream for the treatment of symptomatic AF. For paroxysmal AF, the primary approach has been PVI, primarily with radiofrequency (RF) ablation or cryoballoon ablation. In patients with persistent AF, there have been various adjunctive approaches used in combination with PVI. These approaches have included focal impulse and rotor modulation (FIRM) or “rotor” ablation, LAA isolation, non-PV trigger ablation, linear and point ablation of various combinations, complete posterior wall isolation, and ganglionic plexus ablation. However, no clearly preferred strategy has consistently been demonstrated to be superior. In addition, success rates of ablation for persistent and long-standing persistent AF remained modest in clinical trials.

Creation of Hybrid AF Ablation Program

The challenges of treating this patient population led to the genesis of our hybrid ablation program, which was launched in March 2017. The rationale for the program was to develop a consistent approach to the procedural and periprocedural management of this challenging patient population that could be modified over time as new techniques were developed or validated. Patients undergo a shared decision-making visit with one of our electrophysiologists. If during this process, the patient is considered to be a good candidate for the hybrid ablation protocol, then the patient is referred to the cardiothoracic surgeon. Cases are reviewed in our monthly multidisciplinary AF conference. Standard presurgical workup includes 2-dimensional (2D) echocardiogram, ischemic evaluation, and pulmonary function testing.

We employ a staged approach for our hybrid AF ablation. This simplifies the logistics of the 2 procedures, and allows for complete lesion maturation of the surgical ablation as well as resolution of any associated edema prior to endocardial mapping and ablation. The surgical portion is performed first, followed by a 6-week follow-up office visit. The catheter portion of the procedure is then completed anywhere from 6-12 weeks after the surgical portion.

Stage 1: Surgical AF Ablation and LAA Management

Once patients have been evaluated and determined to be acceptable candidates for surgery, they are evaluated in the preadmission testing (PAT) lab and enrolled in an enhanced recovery after surgery (ERAS) protocol. Anticoagulation is held 48 hours prior to surgery, and patients on warfarin are bridged with enoxaparin.

Upon arrival to the operating room (OR), the patient is induced with general endotracheal anesthesia and a double-lumen tube is placed. A radial arterial line is placed for hemodynamic monitoring and we proceed directly to preoperative transesophageal echocardiography (TEE). Once we have confirmed there is no intracardiac thrombus, we proceed with opening the remaining disposables. An esophageal temperature probe is placed for esophageal temperature monitoring during ablation. The position of the probe is confirmed with portable fluoroscopy, with an ideal location of 1.5-2 vertebral body units below the carina on fluoroscopic imaging.

Through a standard subxiphoid incision, the silastic cannula is advanced along the diaphragmatic surface with a 5 mm endoscope. The anatomy is defined, the EPi-Sense System (AtriCure) is introduced, and multiple lines of ablation are created using RF. A confluent area of ablation is created between both sets of PVs and bordered superiorly by the pericardial reflections (Figure 3) and inferiorly by the coronary sinus.

The second part of the epicardial stage is a left video-assisted thoracic surgery with isolation of the LAA and epicardial occlusion using the AtriClip. A 30-degree, 5 mm endoscope is used for this portion of the surgery. The pericardium is opened inferior to the phrenic nerve to expose the LAA. Since our initial experience, we have now expanded our lesion set to include transection of the ligament of Marshall using bipolar LigaSure technology (Medtronic), reintroducing the EPi-Sense catheter to create additional lines of ablation anterior to the PVs on the left, and extending onto the coumadin ridge. We then measure the base of the LAA, place the occlusion device at the base of the LAA, and confirm placement with intraoperative TEE prior to deployment.

A pleural tube is placed, which is removed the following morning. If the patient is in AF, cardioversion is attempted prior to leaving the OR to restore sinus rhythm.

The patient is transferred to a monitored bed until time of discharge, typically postoperative day 2. We resume anticoagulation the night of surgery with warfarin. The patient is discharged on anticoagulation, antiarrhythmics, a proton pump inhibitor, and a methylprednisolone dose pack to decrease the risk of pericarditis or pleuritis.

Stage 2: AF Ablation

To complete the hybrid AF ablation, the endocardial catheter ablation is scheduled from 6-12 weeks after the surgical epicardial ablation. This delay between the first and second stage allows for epicardial lesion maturation and resolution of any myocardial edema that might limit endocardial mapping. We perform our AF ablation procedures under general anesthesia in the cardiac electrophysiology (EP) lab. A TEE is routinely performed as part of our hybrid cases prior to the endocardial ablation to assess LAA closure and inform any potential future decisions regarding anticoagulation management. Transseptal access is obtained under intracardiac echocardiography (ICE) guidance using a VersaCross RF Wire (Baylis Medical), and a single transseptal puncture technique is used. A high-density endocardial electroanatomic map is completed to assess voltage using a 20-pole, multispline, PentaRay mapping catheter (Biosense Webster, Inc, a Johnson & Johnson company) to collect and assess LA voltage. Voltage thresholds for scar are set to 0.1 or 0.2 mV at baseline and adjusted as appropriate by the operator. ICE is also used to correlate with the 3D map as needed. All endocardial ablation is performed using externally irrigated contact force sensing RF catheters (ThermoCool SmartTouch SF, Biosense Webster). Contact force is monitored with a goal of 10-20 g of contact force, and a tag visualization algorithm (Visitag Surpoint Module, Biosense Webster) is employed to track ablation lesions. We use high power short duration ablation with standard settings of 50 W for 10 seconds on the posterior wall and roof, and 50 W for 10-15 seconds on the anterior wall. An esophageal temperature probe is placed for esophageal temperature monitoring with appropriate position confirmed on fluoroscopy. Our standard lesion set includes wide area circumferential ablation (WACA) to complete isolation of the PVs by anchoring to the epicardial posterior wall ablation lesions set posteriorly, a LA roof line, and a CTI line the majority of the time. Additional ablation is performed as needed depending on the case and the operator.

Based on the posterior wall voltage map, the WACA line can typically be completed by anchoring to the isolated posterior wall inferiorly and superiorly. The pericardial reflections (Figure 2) do limit how superiorly the epicardial posterior wall ablation can reach. Because of this limitation, a LA roof line is typically ablated to ensure isolation of any portion of the posterior wall that could not be reached due to pericardial reflections. This is accomplished by ablating from the anterior-superior portion of the left WACA line to the anterior-superior portion of the right WACA line. Additional LA ablation is performed as needed for LA flutter or, at times, other areas of dense scar and is done at the discretion of the operator.

A CTI ablation line is the only standard right atrial ablation performed. This ablation is performed using a combination of the three-dimensional (3D) electroanatomic mapping and ICE guidance. Right atrial ablation is typically performed at lower power (35-40 W) at the discretion of the operator, and an ablation tag visualization algorithm is used to track ablation location.

Upon completion of the ablation lesion set, a repeat 3D electroanatomic map of the LA is completed to confirm all lesion durability and guide any further needed ablation. This voltage map, in combination with the preablation voltage map, is then later reviewed in our multidisciplinary AF conference, where all cases are reviewed.

Anticoagulation and LAA Management

During the development of our hybrid program, there was much debate about periprocedural anticoagulation management as well as ongoing anticoagulation management in patients that had successful LAA exclusion. Leading up to the first stage of the procedure, all patients are continued on their preexisting anticoagulation. In most cases, this was a direct oral anticoagulant (DOAC) agent. The DOAC agent is held 48 hours prior to the first stage. Postoperatively, patients are then transitioned to warfarin, with the first dose given on the evening of the procedure. The rationale for this transition is to minimize postsurgical bleeding. Patients may be transitioned back to the DOAC at their in-office follow-up prior to the second stage. However, if the patient is stable on warfarin or if the timing of the second stage is within 4 weeks, they may remain on warfarin. At the time of their catheter ablation, a preprocedural TEE is done to evaluate the placement of the AtriClip to guide future decisions about anticoagulation management.

Our team acknowledges the lack of randomized controlled trial (RCT) data supporting the LAA epicardial clip as an alternative to long-term anticoagulation. However, there exists a substantial and growing body of literature surrounding LAA occlusion with endocardial devices. After reviewing the literature, the group came to a consensus that if follow-up TEE demonstrated successful AtriClip placement, defined by a <1 cm LAA stump (Figure 4) with no communication into the body of the LAA, the patient could be offered the option of stopping anticoagulation at 3 months after completion of the second stage. This decision is dependent on there being no other comorbidities warranting continued anticoagulant use. This decision is made through a shared decision-making process with the EP team during in-office follow-up, with thorough discussion of the risks/benefits and explanation of RCT limitations.

Additional Benefits of a Hybrid AF Program

As our program has grown, there have been instances of patients that are newly identified with occlusive CAD or severe valvular disease during the workup for hybrid AF ablation. In these cases, the patients are instead evaluated for coronary artery bypass grafting and/or valve replacement along with a complete biatrial Maze procedure utilizing a Cox-Maze IV lesion set along with LAA management.

In addition, our cardiothoracic program is now routinely referring patients who have had concomitant Maze procedures to our AF clinic for postprocedural evaluation and monitoring for recurrent AF. This has resulted in more patients being weaned off antiarrhythmic therapy such as amiodarone, as well as more subsequent referrals for follow-up catheter ablation procedures in appropriate cases. These patients also receive education on the importance of ongoing risk factor management to reduce risk of recurrent AF as well as progression of CAD.

Since the launch of our program in March 2017, we have done approximately 135 hybrid cases. Of those patients, 71% were ablation naive prior to referral for hybrid ablation. As we continue to monitor the success of our program, primarily defined by reduction in AF burden, we have seen success rates ranging from 80%-85%.

Conclusion

Our hybrid AF ablation program was created as a multidisciplinary program to provide more effective treatment for a difficult-to-treat patient population. It has improved outcomes for patients undergoing concomitant Maze procedures while also strengthening collaboration between the EP and cardiothoracic surgery services. The combined epicardial and endocardial lesion set, along with the hemodynamic and electric exclusion of the LAA, maintains a minimally invasive approach while allowing more effective rhythm control and better symptom control. As future research and technology elucidates alternative and more effective approaches toward the treatment of AF, our program structure allows us to adapt and incorporate these new approaches in a collaborative, multidisciplinary manner. 

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Morris reports consulting fees from AtriCure, Biosense Webster, and Medtronic. Ms Mudd reports consulting fees from AtriCure for peer to peer consulting as requested. Dr Peterson reports consulting fees from AtriCure for peer to peer consulting and proctoring.

Reference

1. Haïssaguerre M, Jaïs P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998;339(10):659-666. doi:10.1056/NEJM199809033391003