Utilizing the Convergent Procedure to Treat Persistent Atrial Fibrillation: Experience at Genesys Regional Medical Center

Background

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and it continues to grow at an alarming rate. It is estimated that currently five million Americans suffer from the disorder, and it is projected to continue to increase in prevalence, with estimates nearing 16-20 million by the year 2050.¹ This supraventricular arrhythmia causes ineffective atrial contraction due to uncoordinated atrial activation. AF symptoms include dyspnea, palpitations, fatigue, hypotension, syncope and decreased exercise tolerance, while increasing the risk of stroke (from formation of atrial thrombi) and congestive heart failure.²

Therapy has consisted of a triad including thromboembolic prevention, rate control, or rhythm control. Pharmacologic options have included aspirin, warfarin or novel anticoagulants for thromboembolic prophylaxis, and atrioventricular nodal agents or antiarrhythmic medications for rate control or rhythm control. Over the last decade, radiofrequency ablation has become the number one option for patients when pharmacological agents have failed or not been tolerated. Strategies for ablation continue to change as more has been learned about the pathophysiology of atrial fibrillation. 

For paroxysmal AF localized to the pulmonary veins, endocardial ablation is the preferred approach and has demonstrated itself as an effective tool in achieving rhythm control. Paroxysmal patients can typically be managed with drug therapy or pulmonary vein isolation (PVI) with endocardial ablation. 

Persistent AF patients have traditionally required a more aggressive approach including isolation of pulmonary veins, ablation of complex fractionated atrial electrograms (CFAE), and/or a cavotricuspid isthmus (CTI) line. There are a growing number of patients who, despite traditional ablation approaches, and with or without antiarrhythmic medications (AADs), are unable to maintain sinus rhythm (SR). After restoration of SR, it is likely AF resumes because of the longstanding duration of AF, underlying atrial disease, and remodeling along the posterior left atrium. 

For these patients, a new procedure has been developed that combines endocardial radiofrequency (RF) ablation and epicardial ablation into a hybrid approach called the Convergent procedure. Given the disease progression from paroxysmal to persistent AF, the Convergent procedure is treating a more challenging patient population. Epicardial ablation in conjunction with endocardial ablation shows promise for persistent AF, which is associated with diffuse disease of the atrial substrate.

About the Procedure

The Convergent procedure involves the electrophysiologists, cardiothoracic surgeons, and OR/EP staff as a single procedure, most often in an EP lab or hybrid EP suite. The patient initially goes through an extensive cardiac screening including history and physical. Prior to the procedure, a transesophageal echo is performed. The patient is connected to EKG leads and 3D electroanatomic mapping pads. Lying in the supine position, the patient is given general anesthesia, intubated, and then prepped and draped to prepare for the initial surgical portion. The surgeons begin by obtaining pericardial access, with three small incisions near the upper abdomen and subxiphoid region. The surgeons initially perform laparoscopy using a 12mm subxiphoid port and one 5mm port each in the left upper quadrant and right upper quadrant of the abdomen. The diaphragm is then traversed (using electrocautery) just anterior to the left lobe of the liver to enter the posterior pericardium. The 12mm port is then replaced with the Subtle^® Cannula (nContact, Inc.), through which a 7mm endoscope and the ablation device (EPi-Sense^® Guided Coagulation System with VisiTrax^®, nContact, Inc.) are placed, allowing endoscopic visualization of the left atrium as ablation proceeds. Using continuous irrigation, overlapping epicardial lesions are created across the posterior wall of the left atrium, and isolation lines are also placed around the right- and left-sided pulmonary veins. This epicardial ablation offers the advantage of avoiding endocardial ablation near the esophagus, thus minimizing the concern of esophageal injury. The RF ablation device controls cardiac tissue by utilizing suction to provide consistent contact, circulating saline to cool the device for better energy delivery to the tissue. The size of each lesion is 3cm x 1cm. The number of epicardial lesions are based on the size of the patient’s left atrium. Typically, about thirty 90-second linear lesions are created to ensure completeness. The drain is placed in the pericardial space and the incisions are then closed.

Immediately following the epicardial portion of the procedure, the patient is prepped and draped for endocardial ablation. The electrophysiologist performs transseptal catheterization, and additional endocardial lesions are placed. More specifically, voltage maps are created in the left atrium using the Carto 3 system (Biosense Webster, Inc., a Johnson & Johnson company). By mapping endocardially, true lesion transmurality can be assessed. This informs the electrophysiologist where there is nonconductive tissue versus healthy areas still requiring ablation lesions. The electrophysiologist will confirm traditional endpoints of PVI and verify the absence of excited atrial tissue. 

Convergent procedure results published from U.S. and European centers have demonstrated 79-95% of patients maintained SR at one-year follow-up, and results off AAD therapy showed 64-81% in SR at one year.^3-8 At Heart Rhythm 2015, the largest single-center Convergent procedure experience reported outcomes for 248 patients followed for one year, with 93% in SR and 66% in SR off AADs.³ Recent long-term single-center outcomes from Europe showed promise for maintaining SR for many years, with 76% of patients in SR at four-year follow-up and 69% in SR and off AADs.⁴

By applying both epicardial and endocardial lesions, the team at Genesys Regional Medical Center has been able to target multiple mechanisms responsible for AF in one procedure including pulmonary vein tachycardia, rotors, complex fractionated electrograms, and ganglionic denervation. “We have been pleased with the results, even with our most complicated patients, including those with persistent atrial fibrillation and left atrial enlargement that have been refractory to prior ablation techniques,” stated electrophysiologist Matthew Ebinger, DO, one of Genesys Regional Medical Centers operators performing the Convergent procedure. 

Experience at Genesys Regional Medical Center

Genesys Regional Medical Center is the first hospital in Michigan to offer the Convergent procedure. To date, we have performed 28 Convergent procedures; our first Convergent patient was in January 2014. Kimberly Bonzheim, director of cardiovascular services, notes that “Bringing both the surgical and EP perspective together in one setting gives the patient the best of both methods. We are very pleased to provide this comprehensive approach to patient care.”

By using our new EP/hybrid lab, we have been able to efficiently conduct these complex cases. Physicians and OR/EP staff work together to ensure timely turnover. A big challenge in any workplace is merging two different disciplines or departments in relation to the learning curve; we have overcome this obstacle through adopting a hybrid team approach. For a successful program, it is very important for the electrophysiologist and the cardiac surgeon to maintain a good relationship. Early on, this was key and we were able to all work together establishing our tasks and responsibilities. Changes in workflow had to be met, allowing surgeons to perform in our hybrid lab initially, changing the endocardial ablation start time to late morning/early afternoon. Procedures need to be scheduled accordingly. EP/Cath Lab Manager Vanessa Derwin states that “conquering challenges, finding our own roles, and keeping consistent” have been essential factors to success. To prepare for the procedure, we initially conducted dry runs to better learn our specific roles and to address any foreseen issues. Cooperation and respect between departments is necessary for a successful program. We continue to collaborate after cases to discuss if any changes should be made to better the workflow and environment. In addition, because patients are not returning as they would for repeat endocardial ablation alone, this procedure has been cost-effective by avoiding further hospitalizations for these patients.

Case Study

A 63-year-old male with a three-year history of longstanding persistent AF presented to the lab. This patient was symptomatic and complained of his decreased quality of life due to the worsening shortness of breath and fatigue. He had been initially medically managed with AADs; however, he remained refractory and still required several cardioversions. The cardioversions were not able to maintain SR and his rhythm reverted to AF shortly thereafter. When two endocardial RF ablations had failed, the patient was in search of another option; our team proposed the Convergent procedure.  

After a complete history and physical, the patient was cleared to stop anticoagulation prior to the procedure. Subsequently, a TEE was done to rule out thrombus. The patient was prepped, intubated, and placed under general anesthesia. The surgeons gained subxiphoid access, and inserted suctioning and ablation probes into the pericardium (using nContact equipment). This patient’s Convergent procedure consisted of 34 epicardial lesions (90 seconds per lesion) that were placed on the posterior atrial wall. The electrophysiologist then gained access through the right and left femoral veins. The coronary sinus catheter was advanced followed by the ICE catheter for echo guidance in transseptal access. The extra sharp Brockenbrough needle was then advanced to the atrial septum. Once transseptal was obtained and three stable blood pressures were recorded, the mapping and ablation catheters were then positioned in the left atrium. Once the voltage map was created utilizing Carto 3 (Biosense Webster, Inc., a Johnson & Johnson company), the electrophysiologist placed the endocardial lesions. The mapping process validated tissue nonconductivity across the posterior atrial wall, requiring minimal endocardial lesions. Voltage was shown to still be elevated (as in healthy tissue) in some areas around the right-sided pulmonary veins; thus, PVI was obtained with endocardial lesions. Once the ablation process was complete, the physician confirmed isolation in all four pulmonary veins with entrance and exit block pacing maneuvers. A post-ablation voltage map confirmed tissue nonconductivity and isolation. The scars were extensive between the two techniques, covering the posterior wall, carina and around all pulmonary veins. The patient was extubated, and later discharged two days post procedure. Within the following six months, antiarrhythmics were discontinued; the patient has been asymptomatic with no reoccurrence of AF and is maintaining sinus rhythm.

Final Thoughts

Through the use of the Convergent procedure and a solid, focused team, we have been able to accomplish our goal of offering a safe and successful procedure to persistent and longstanding persistent AF patients. We have found this collaborative approach to offer a high success rate, even for patients with previous failed ablations. With a minimally invasive epicardial-endocardial technique, the Convergent procedure has increased the efficacy of a standalone endocardial catheter approach at our center. Genesys Regional Medical Center has established recognition for providing new therapy options and multidisciplinary care in this challenging patient population. As a result, we have attracted patients who may not have come to this hospital prior. Our main objective is to improve the quality of life in these patients by restoring a normal heart rhythm. The Convergent procedure does just that — providing AF patients with new hope.

References 

1. Atrial Fibrillation Facts that May Surprise You. PhysiciansWeekly.com, published August 29, 2012. Available online at https://www.physiciansweekly.com/atrial-fibrillation-awareness-month/. Accessed February 13, 2015.
2. 2014 AHA/ACC/HRS Guideline for the Management of Patients with Atrial Fibrillation. J Am Coll Cardiol. 2014;64(21):2246-2280.
3. Civello KC, et al. Convergent procedure: Retrospective one year outcomes reported for the largest single center cohort of patients. Heart Rhythm. 2015;12(5);Suppl 1:S262.
4. Gersak B, et al. Long term (4 years) Convergent procedure outcomes documented by implanted loop recorders. Heart Rhythm. 2015;12(5);Suppl 1:S431.
5. Gersak B, Zembala MO, Müller D, et al. European experience of the convergent atrial fibrillation procedure: multicenter outcomes in consecutive patients. J Thorac Cardiovasc Surg. 2013;147(4):1411-1416.
6. Gilligan DM, Joyner CA, Bundy GM. Multidisciplinary collaboration for the treatment of atrial fibrillation: convergent procedure outcomes from a single center. Innovations in CRM. 2013;4(10):1396-1403.
7. Zembala MO, Suwalski P. Minimally invasive surgery for atrial fibrillation. J Thorac Dis. 2013;5(S6):S704-S712.
8. Golden K, et al. Clinical outcomes of a new epicardial/endocardial ablation procedure (Convergent) for the treatment of atrial fibrillation. Heart Rhythm Society Annual Scientific Sessions, May 2012.

Disclosure: The author has no conflicts of interest to report regarding the content herein.