The Convergent Procedure: The CONVERGE IDE Clinical Trial

In this feature interview we learn more about the multicenter CONVERGE Study, nContact’s randomized IDE Study for the treatment of persistent atrial fibrillation (AF) through a multidisciplinary closed-chest approach. The CONVERGE Study will randomize patients 2:1 between nContact’s epicardial-endocardial Convergent Procedure using the EPi-Sense^™-AF guided Coagulation System with VisiTrax^® and standalone endocardial ablation using fluid-irrigated catheters. 

Here EP Lab Digest^® speaks with physicians from the first two sites to enroll patients in the CONVERGE Study: John R. Onufer, MD of Virginia Cardiovascular Specialists, Levinson Heart Hospital in Richmond, Virginia, and Graham Bundy, MD of Cardiothoracic Surgical Associates, Levinson Heart Hospital in Richmond; and David R. Tschopp, MD of Austin Heart in Austin, Texas, and Faraz Kerendi, MD of Cardiothoracic and Vascular Surgeons in Austin.  

Please tell us briefly about the CONVERGE IDE Clinical Trial. 

Tschopp: The CONVERGE Study is designed to compare standard endocardial ablation to a combined epicardial-endocardial ablation in patients with longstanding persistent AF.

Bundy: This is a randomized study comparing catheter-based treatment with an epicardial and endocardial ablation strategy to treat atrial fibrillation. 

Onufer: The purpose is to find the best approach with the most durable results to restore normal rhythm in patients with persistent AF over seven days. This is a large population of patients that tend to be highly symptomatic. We’ve been doing the hybrid procedure with the nContact device for about four or five years now, and have noted that our results have been quite good in terms of managing patients and only requiring one procedure. Therefore, this needed to be looked at in a much more systematic way to confirm that this wasn’t just our patient selection or the way we uniquely did the procedure, but instead was applicable to everyone. The goal is to determine whether this is a better first-time procedure than catheter ablation in these patients. 

What are some of the eligibility criteria for the CONVERGE Study?  

Tschopp: Patients have to be greater than 18 years of age and less than 80, they have to have had AF for less than 10 years, be refractory or intolerant to at least one antiarrhythmic drug (class I and/or III), and have documented persistent AF. 

Onufer: Eligible patients need documentation of persistent AF, their ejection fraction has to be greater than 40 percent, and have no valvular heart disease. They have to have failed an antiarrhythmic drug and be willing to be a candidate for either catheter ablation or a combined catheter and surgical ablation. 

Are there patients who are ineligible to participate?  

Tschopp: Patients who are ineligible include those who previously had open-heart surgery or left atrial ablations. Patients with paroxysmal AF and patients who are contraindicated for anticoagulants are also excluded. 

Kerendi: Patients with a low left ventricular ejection fraction are also excluded. 

Please tell us how the CONVERGE Study’s treatment — the epicardial-endocardial Convergent Procedure — is performed. 

Kerendi: The epicardial portion is done through a transabdominal, transdiaphragmatic approach, in which we make a small incision in the central portion of the diaphragm and then put in a pericardioscope. We visualize the epicardial surface of the left atrium and pulmonary veins, and do as much of the ablation from the external aspect of the atrium that we can. We’re limited by where the pericardium is actually adhered to those structures, so we cannot do the entire area that we would want to. This is where the endocardial part comes in — to finish off the areas that we’re unable to get to. 

Tschopp: From the endocardial perspective, regardless of whether or not you’re doing a Convergent Procedure, you always isolate the pulmonary veins; in longstanding persistent AF patients, many if not most physicians will isolate the posterior wall. In addition to that, physicians will frequently do a cavotricuspid isthmus ablation line. When you’re doing a Convergent Procedure, since the surgeon has already done an epicardial ablation, the posterior wall is pretty much isolated. Therefore, you only need to focus on completing the isolation of the pulmonary veins, which primarily involves ablation over the areas of pericardial reflection that aren’t adequately ablated by the epicardial approach, and then completing the cavotricuspid isthmus ablation. 

Bundy: The procedure starts with the patient undergoing a fairly excessive cardiac screening including possible cardiac catheterization and TEE, as well as a thorough history and physical exam, so by the time they get to the operating room, we’re confident they’re good candidates for the procedure. I begin with a 2 cm subxiphoid incision, an abdominal incision just below the xiphoid process in the midline, then insufflate the abdomen with carbon dioxide and place two 5 mm ports in the left and right upper quadrants. Next we retract the liver caudally and make a small left 2 cm incision transversally in the central tendon of the diaphragm. Then I use a large hollow cannula to gain access in the pericardial space. Through that cannula, I can advance my catheter, which has a 3 cm ablation coil and is approximately 1 cm wide. It is an irrigated system with vacuum assistance to facilitate contact with the epicardial surface. It provides a fairly large area of ablation during a 90-second ablation. I focus on ablating the entire posterior left atrium between the pulmonary veins, ablate within the oblique sinus, anterior to the left-sided pulmonary veins and advance the catheter toward the ligament of Marshall. Then I advance the cannula over the inferior vena cava and ablate the veins anteriorly on the right side — the superior veins and inferior veins — and ablate down into the oblique sinus. What I cannot access epicardially, Dr. Onufer and his associates can get to endocardially. When I’m finished with the epicardial portion of the procedure, which takes about an hour and a half to two hours, I leave a drain in the pericardial space, and close the diaphragm and abdominal incisions. Then Dr. Onufer or one of his associates will come in and perform electrophysiologic mapping and ablation. 

Onufer: After his completion of the epicardial approach, we place catheters exactly like we would for any AF ablation; this includes placing a coronary sinus catheter, an intracardiac ultrasound catheter to visualize the transseptal and monitor for any complications, and either a lasso or spiral catheter and an irrigated tip catheter are placed into the left atrium along with a His catheter. We’ll also create a voltage map of the left atrium beforehand to see 3D geometry and identify any gaps. Then we ablate to complete the pulmonary vein isolation. Upon completion of this, we typically see a marked reduction of voltage in the posterior left atrium. However, everyone has needed some type of additional lesions around their pulmonary veins to get complete isolation. The nContact lesion set does not completely isolate the pulmonary veins, which we don’t look at as any detriment, it’s just part of the synergistic or combined effect we’re trying to achieve with doing both procedures. So after doing pulmonary vein isolation and confirming block, we’ll typically challenge with isoproterenol and programmed stimulation. If we induce any atrial flutters or atrial tachycardias, we’ll eliminate those. After this, the catheters are withdrawn and the patient is sent to the ICU under full anticoagulation with coumadin. They are monitored in the ICU for about two days, and usually go home after the second day. The pericardial drain placed by the surgeon is usually taken out the day after the procedure, or within the first postoperative day. 

The Convergent Procedure is a hybrid procedure; how does it differ from other hybrid ablations? Does it require a new room or new equipment? 

Onufer: In terms of other hybrid ablations, the procedure is staged into two separate procedures so the surgeon performs isolation of each of the pulmonary veins in one setting, and then the patient comes back in a second setting for the endocardial ablation. It’s interventionally very different and requires thoracoscopic access. That being said, the Convergent Procedure is done in a single procedure setting.  There is usually less pain and earlier discharge with epicardial ablation from the subxiphoid approach. In terms of the facility needed, we use a hybrid room, which means that the EP lab is completely conducive to the surgeon bringing in their equipment for the procedure. The room is set up for OR capability and is larger to accommodate surgical equipment. 

Kerendi: Other hybrid ablation approaches require either a thoracotomy or thoracoscopy via a 3 or 4 port approach. The only other hybrid procedure that’s commonly performed involves the bilateral thoracoscopic approach. First, to access the pulmonary veins and the atrium on the right side, and then do a similar approach on the left side; this makes a total of 6-8 incisions and takes longer to accomplish compared to what we do. With the Convergent Procedure there are only two incisions made in the abdomen, which is better from a pain standpoint. From a case duration standpoint, the Convergent Procedure is much shorter than any other approach out there. 

Tschopp: I believe there are actually two available hybrid procedures other than the Convergent Procedure, but both require thoracoscopy. The Convergent Procedure is the least invasive epicardial approach to successfully isolate the posterior wall, so that is a significant advantage, especially when it’s coupled with a reduced morbidity. 

Kerendi: It also has the advantage of ablating on the surface of the heart and ganglionated plexi, which are thought to be important contributors to AF. 

Tschopp: I agree that they are very successful at ablating ganglia, particularly at the roof, right side of the left superior pulmonary veins and along the inferior margin of the right pulmonary veins. Again, I cannot emphasize enough how well the posterior wall is isolated by this approach prior to doing any endocardial ablation. 

How does a multidisciplinary procedure such as the Convergent Procedure also benefit the hospital?

Tschopp: It’s a cost-effective procedure for the hospital in terms of time, staff and room requirements. We currently perform the Convergent Procedure consecutively in a standard EP lab or hybrid room. 

Kerendi: In addition, I think it certainly can be considered cost-effective if you are able to avoid a second hospitalization in patients coming back after catheter ablation only. 

Bundy: As a group of collaborating physicians, we have attracted the attention of patients from the community as well as other practitioners involved in the care of patients with AF. The physicians I have been working with very closely — Dr. Onufer, Dr. David Gilligan, and Dr. Charles Joyner, Dr. Daniel Schneider and Dr. Saumil Shah — believe that based on our anecdotal experience at this point, the addition of the epicardial portion of the procedure has increased the efficacy of the catheter-based approach. I think this has established recognition for the hospital as being the only place in Richmond not to mention central Virginia to offer this right now; I think we have attracted patients who perhaps might not have come to Chippenham Hospital.  

Some might consider a multidisciplinary procedure daunting. Did you have to overcome any early challenges in integrating EP and cardiothoracic surgery for the Convergent Procedure?

Kerendi: It definitely was a collaborative team approach. It’s important for there to be a good relationship between the electrophysiologist and the cardiac surgeon, otherwise it’s not going to be a successful program. Early on we were able to work together well, and that was a key part of it. 

Onufer: I would consider the only real difference is that it changes your workflow slightly. In order to perform the procedure, the surgeon needs the EP lab during the morning; it is about 11 am when we start getting access with our catheters. This means that we have to find other rooms or rearrange procedures. With that being said, Dr. Bundy has been an excellent partner in all aspects of the care of these patients. 

Bundy: When I was looking at available procedures, it was hard to persuade cardiologists that I had anything to offer that wasn’t going to be necessarily painful or perhaps even detrimental to patients. The drawback to thoracoscopic and bilateral thoracotomy procedures is that they require a fairly complex anesthetic, you have to deflate the lungs, and you often have to make fairly decent-sized chest incisions. There was very little out there at the time that was a multidisciplinary approach in which the electrophysiologist and surgeon were working together. The cardiologists that I’m working with now — Drs. Onufer, Gilligan and Joyner, Shah and Schneider — have all been very pleased with the Convergent Procedure because it is a collaborative approach and requires a fairly minimal surgical procedure. 

Tell me more about your experience treating persistent AF patients at your facility. How many procedures have you done?

Kerendi: We’ve been doing the Convergent Procedure for a little over two years now. 

Tschopp: I believe we’ve treated about 120 patients.

Onufer: At our facility we do over 200 AF ablations per year, and about 30-40 percent are persistent AF. However, not all of these patients are candidates for the Convergent Procedure because of a previous history of coronary bypass or cardiac surgery. We do not recommend the Convergent Procedure in patients with a high likelihood of difficult epicardial access or pericardial adhesions. 

The CONVERGE Study is for persistent AF patients. How do these patients differ from paroxysmal AF patients? What are some of the challenges you face when treating persistent AF patients?

Tschopp: The biggest difference is having long-term successful procedures. The ability to maintain normal rhythm is a challenge in persistent AF patients through any means, such as drugs or catheter ablation. This study is intended to demonstrate a benefit of the combined epicardial-endocardial approach for success at maintaining normal rhythm in the long run when compared to the standard of care.

It’s intended to demonstrate a step forward in terms of their management. Paroxysmal patients can be managed by drug therapy alone or by endocardial ablation techniques that involve isolation of the pulmonary veins. When you have a patient with persistent or longstanding persistent AF, they need a more aggressive ablation approach with isolation of the veins, isolation of the posterior wall, ablation of the complex fractionated atrial electrograms, and ablation of the cavotricuspid isthmus. They require more extensive atrial ablation to have any hope of maintaining normal rhythm, and even then, they frequently have higher fail rates of ablation. 

Bundy: Electrophysiologists know that persistent AF patients have a lower success rate with a catheter-based approach alone. They have been looking for an alternative treatment strategy that has the potential to improve upon the efficacy of treating people with persistent AF. 

Onufer: Although there is an overlap between persistent and paroxysmal AF, patients with persistent AF tend to have more substrate involvement in their AF. This means isolation of the pulmonary veins is not enough to maintain long-term sinus rhythm. 

How do you address challenges regarding patient enrollment for clinical studies at your center?  

Bundy: One of the challenges that I’ve had so far is that some patients seem to be aware of the study and have opted for the Convergent Procedure rather than to be randomized. Even though formal clinical trial data is not yet available, which we communicate to patients, people have come to believe that the surgical portion of the procedure adds efficacy, and they’re hoping for the best success possible. So it’s an interesting phenomenon.  

Tschopp: What generally happens is patients with persistent AF are first seen in the EP clinic, and then we refer them to both cardiothoracic surgery and our research department to simultaneously gauge whether they would be candidates for the trial. Assuming the patients are approved by both departments and have interest in the trial, they are enrolled in the trial. 

Kerendi: This is a good question, as it can be somewhat difficult when dealing with a randomized trial. We’re presented on one side saying we think this might be a better and more efficacious option for the patient, but we’re going to randomize this to a different procedure, so we have had a little bit of a challenge there.  

Tschopp: Yes, it can be difficult because people will frequently ask me which procedure I think is better. Since we’ve been doing this procedure for two years, I would tend to answer that the combined approach is better, but we’re doing this study to prove that fact. There are some issues with people agreeing to be randomized. We can be honest in that there is no hard evidence and that I’m correct in my assumption. Also, patients are randomized in a 2:1 fashion — so two people get the combined epicardial-endocardial approach for every one person who receives the endocardial procedure alone. 

What factors are patients most concerned about when considering participation in a clinical trial? 

Kerendi: Being randomized is certainly one factor; a second factor is letting patients know that even though they’re going to be part of a trial, the procedure is not truly experimental — we have two years of experience with this procedure with over 120 patients treated.  

Onufer: I have found that some patients want a less invasive procedure, while other patients think more is better, opting for both the catheter and surgical ablation. 

How does the CONVERGE Study differ from previous catheter-based clinical trials for AF?

Kerendi: To my knowledge this is the first trial to include a surgical ablation component to it — it is the first trial to randomize a persistent AF population to a hybrid approach versus catheter ablation only. 

Onufer: The major difference is this trial is randomized between two interventional approaches — a catheter-based procedure and surgical ablation. This is unique in that all the catheter-based procedures for AF have been randomized to another failed medication rather than to another device. There has been no other combined surgical catheter ablation procedure versus another catheter ablation procedure, particularly for the persistent patient population.  

Is there anything else you’d like to add?

Bundy: This has been a very positive collaboration — Dr. Onufer, Dr. Joyner, Dr. Gilligan, as well as Dr. Daniel Schneider and Dr. Saumil Shah have all been very welcoming in adding cardiothoracic surgeons to their armentarium to help treat patients with AF.  I would also like to thank Dr. Bob Sperry, one of the EPs in Richmond with whom I’ve worked closely.  While he is not involved in the Convergent Procedures, he was very supportive of the program from it’s inception, and I can thank him for a significant part in getting it off the ground. From an investigational standpoint, it will be very interesting to see what the results of the study will hold in terms of the difference in efficacy. 

Disclosures: The authors have no conflicts of interest to report. Outside the submitted work, Dr. Kerendi reports consultancy with nContact, Inc., and Dr. Tschopp reports honoraria from nContact, Inc. from a previous speaking engagement.