 Hello, my name is Jennifer Kozard. I'm a cardiovascular surgeon at Texas Heart Institute. I want to thank Texas Heart Institute and Baylor St. Luke's Medical Center for inviting me to speak today. I'll be speaking about atrial fibrillation and the surgical management options of this common disease. Specifically about new approaches for surgical treatment of refractory or long-standing AFib. I have no disclosures. So atrial fibrillation is the most common cardiac arrhythmia, affecting more than 33 million individuals worldwide and in the U.S. Over three million people have atrial fibrillation. It's associated with increased risk of thromboembolic events like stroke, peripheral ischemia, also increased mortality and reduced quality of life. AFib is known to increase the risk of stroke by an average of five-fold, and it's also linked to an increased risk of sudden death. Persistent atrial fibrillation is often a treatment challenge due to the electrical and anatomic differences among different patients. There can be variability in the scar burden and location of origin and also left atrial enlargement and patients often have other comorbidities as well. This is a busy slide, but just briefly showing that there are many different mechanisms for atrial fibrillation. It's a heterogeneous disease and can have a variety of different electrical abnormalities. There can be single or multiple foci of abnormality, also multiple re-entrant circuits or wavelets. The majority of these abnormalities are found in the left atrium and also near the pulmonary veins, but they can arise in other areas of the heart as well. There are several different types of AFib I want to quickly define. Mostly paroxysmal atrial fibrillation, which is AFib that resolves within seven days of onset and non-paroxysmal atrial fibrillation, which consists of persistent atrial fibrillation, which is continuous AFib, sustained more than seven days, and long-standing persistent AFib. Which is AFib that is continuous for more than 12 months. Now I'll get into the treatments for atrial fibrillation. Medications are typically first-line treatment. I won't go over that, but antiarrhythmics, anticoagulants, and rate-control drug drugs are often used in combination. Most procedures for atrial fibrillation target treatment of the left atrial wall because, as I said earlier, it's a critical part of initiating and maintaining persistent atrial fibrillation. Some procedures also target the right atrium as well. Endocardial ablation is done by electrophysiologists and is somewhat effective, but it can be difficult to treat patients with persistent or long-standing atrial fibrillation with this technique alone. It usually requires repeat ablations for good results and multiple ablations can lead to the dreaded complication of esophageal or phrenic injury. The techniques I'll cover more are surgical in nature. Surgery is obviously invasive treatment, and it does involve prolonged recovery compared to endocardial ablation alone. The Cox-Maze procedure is still the gold standard of surgical treatment for atrial fibrillation. It can be technically challenging and complex. It does require cardiopulmonary bypass, which endocardial treatment alone does not. It can be done through an open sternotomy or through minimal access surgery, and it has a very high success rate quoted from 85 to 95 percent freedom from AFib long-term. Other techniques are the mini-Maze, which is a mix of different approaches and lesions, pulmonary vein isolation, which only treats part of the left atrial wall, and part of the problem in physicians really knowing the real clinical results of AFib surgery is that when a patient does have surgery, the ablation techniques or patterns that are actually used in surgery can be very different going all the way from a full Cox-Maze to just pulmonary vein isolation. The convergent procedure or the hybrid approach is a newer technique, which I'll go over more in depth. It's a multidisciplinary approach that combines both endocardial and epicardial ablation, and it provides maximal treatment of the left atrial tissue. Closure of the left atrial appendage is also very important in the treatment of atrial fibrillation, and this can be done either concomitant with other surgery or even as a standalone procedure. So, when should you call a surgeon for treatment of atrial fibrillation? There are two major categories for consideration of surgical ablation for atrial fibrillation. Number one is if a patient has AFib and other concomitant cardiac abnormalities requiring surgery, like if they have a valve problem requiring valve surgery or coronary bypass, all patients with symptomatic AFib should be considered for surgical ablation at the time of concomitant surgery. Of course, if a patient has a reasonable risk and the ablation doesn't significantly lengthen the time of cardiable pulmonary bypass or increase the risk of the surgery. Number two, if a patient has atrial fibrillation without any other concomitant cardiac problems, a standalone surgical ablation should be considered for patients if they have either filled medical therapy, if they have persistent AFib after filled endocardial ablation, if they have long-standing persistent atrial fibrillation, either with or without a prior ablation, you can consider hybrid ablation or the convergent approach either open or standard open or minimally invasive maze for any of these patients. Okay, so for a patient with atrial fibrillation and endocardial or left atrial appendage thrombus, surgical approach should be considered because endocardial approaches alone, like the watchman, is contraindicated to the high risk of embolization with a known thrombus. Also, if a patient has a contraindication for endocoagulation like a GI bleed, hemorrhagic stroke, or other bleeding problems, a standalone epicardial left atrial appendage closure can be considered as a standalone. Atroclip can be done, and this does give excellent closure of the left atrial appendage and significantly reduces stroke risk. If a patient has a very large left atrium treatment with endocardial ablations alone is known to be minimally effective, and so surgery can be considered in these patients. So, this diagram shows the classic cut-and-sew coxamase 3 procedure, which is the basis of all the ablations for atrial fibrillation, which, and I want to go through this just to kind of give a, kind of lay the groundwork of all the other treatments to come. Surgical treatment of AFib was first performed over 25 years ago by Dr. James Cox in 1987 in St. Louis. Since then the full coxamase lesion set has proved to be highly effective and result in a high cure rate for AFib. The maze pattern of lesions was chosen to prevent multiple erratic impulses from propagating to cause AFib, but also leaving behind the ability of activating both atria and creating a normal sinus rhythm. This technique involved making multiple left and right atrial incisions that, when they were closed, formed a set of scars which isolated the pulmonary veins and posterior left atrium, as well as the right atrium. These lesions are meant to direct the sinus impulse from the SA node to the AV node along a specified route, and in theory allows coordinated electrical activation of the entire atrial myocardium. This coxamase 3 procedure, as I said, is the basis of all subsequent minimally invasive approaches and also endovascular approaches. This shows the lesions for the coxamase 4, which is a later iteration of the coxamase 3. It uses a combination of incisions and alternate energy sources like bipolar radiofrequency and cryoablation, which are shown here to the right, to complete the full lesion set instead of all incisions. This makes for an easier, quicker, and safer operation, but with the same end goal of the coxamase 3. The coxamase 4 can be performed through an open chest or also minimally invasive, but it does require cardiopulmonary bypass and cardiac arrest. This can be done alone or with other cardiac procedures as well. The key components of a proper maze procedure is isolation of the pulmonary veins and isolation of the posterior left atrium or the box lesion, excision or closure of the left atrial appendage, and isolation of the right atrium. This shows the coxamase 4 technique, which this represents an open sternotomy approach with bicable cannulation. On the left of the screen, you can see the right atrial lesion sets. This portion can be done with a beating heart. On the right, the left atrial lesion set does require cardiac arrest. This is just a representation of the coxamase 4, which can also be performed minimally invasive with femoral cannulation through a right mini thoracotomy submemory incision. Dr. Damiato et al. did a review of the coxamase 3 and coxamase 4 studies in 2017 comparing both of these treatments for atrial fibrillation. The coxamase 4 has proven to have similar results at one year. However, they did show lower results at five years compared to the coxamase 3. This could be due to different follow-up methods, but overall the coxamase 4 in most literature still has excellent long-term results and is still considered the current gold standard treatment for treatment of atrial fibrillation. I want to mention consideration of atrial fibrillation at the time of concomitant surgery, which is very important and should never be overlooked. In patients undergoing coronary bypass or aortic valve replacement patients with non-peroxysmal AFib, it is still considered the best option to perform a maze procedure at the time of surgery, which can offer close to 90% reduction of atrial fibrillation and it also adds stroke protection. If pulmonary vein isolation is done alone with a left atrial clip, that only provides about 30% improvement of atrial fibrillation and stroke protection at a very minimum in addition to concomitant surgery. A left atrial appendage clip or closure does provide stroke protection and gives about a 10% reduction in atrial fibrillation. Similarly, patients undergoing mitral valve surgery should be considered for a full coxamase procedure. During mitral surgery the atrium is opened anyway and therefore if the patient's unacceptable risk, a full coxamase is still the best way to prevent atrial fibrillation at very minimum again. The left atrial appendage clip is easy to perform, doesn't increase any significant operative time and gives stroke protection. The newest treatment option for refractory atrial fibrillation is the convergent procedure which is a hybrid approach to atrial fibrillation. It's a team effort of both an electrophysiologist and a cardiac surgeon. It consists of two procedures that are staged four to six weeks apart. The first part is a surgical or epicardial ablation and you can include the left atrial appendage closure at the same time. The second part is the endocardial mapping by the electrocardiologist and endocardial ablation at that time. This is a staged approach which is preferred to give the epicardial lesions from surgery time to heal and scar so that leads to a more accurate endocardial mapping and limits the need for extensive endocardial ablation at the second procedure. There are two targeted patient groups for the convergent ablation. Those with longstanding persistent atrial fibrillation or AFib more than a year and those who have persistent atrial fibrillation with recurrence after failed endocardial ablation. The ideal convergent patient would be one with longstanding persistent AFib. Two or less prior endocardial ablations however they can have more. No prior cardiothoracic surgery and low or normal cardiac risk for surgical intervention. Contraindications to the convergent are patients with prior cardiac surgery. If they need concomitant surgery that should be done through a surgical open approach. If they have a history of chest radiation or paracarditis they should not undergo convergent. In the spring of 2021 the episodes device by Atrocure was approved by the FDA for treatment of longstanding persistent AFib with a convergent approach. The converged trial demonstrated superiority of the hybrid AF therapy compared to endocardial catheter ablation alone and I'll discuss this further. But first I'll describe how the convergent approach is performed. Convergent AFib ablation begins with the surgical procedure. Transesophageal echocardiogram is used first to rule out left atrial thrombus. If a thrombus in the left atrial appendage or the atrium is present then the case is aborted due to the risk of embolization and stroke. If the heart's clear then we proceed. A subzyphoid paracardial window is then performed and cannulation with a thoracoscope is placed into the posterior paracardium. This diagram shows the epicent's coagulation device that's used for convergent ablation. It's a radiofrequency device that creates a three centimeter linear ablation line. Vacuum suction is used to pull the tissue into the device for engagement and the field is filled with saline to cool the temperature of the surrounding tissue. This video shows the surgical procedure. The subzyphoid decision is made and the cannula with the camera and epicent's device is inserted into the posterior paracardium. The epicent's device is then used to create multiple linear ablation lines to completely cover the posterior left atrial wall between the pulmonary veins. This recreates the box lesion from the COXME's procedure. One benefit of this epicardial ablation approach is that the ablation energy is directed away from the esophagus and directly toward the heart which further decreases the chance of esophageal injury. For the second stage of the convergent approach, which is usually four to six weeks after surgical ablation, endocardial mapping and catheter ablation is done to treat any gaps in the ablation lines or areas that are not able to be reached with the epicardial approach. This is typically on the roof line or even near the pulmonary veins. This diagram shows a complete lesion set of the convergent approach. The blue epicardial lesions are shown here and the red is the endocardial lesions performed during the second stage. The goal is AFib substrate reduction or debulking of the tissue that causes AFib. The entire posterior left atrial wall should be ablated and the pulmonary veins are completely isolated. The end result is the equivalent to the box lesion set from the COXME's procedure. Complications can include esophageal injury. We do monitor the esophageal temperature throughout the procedure. Pericarditis or pericardial effusion is also something that we try to prevent post-op because it's a known complication and we provide steroids, colchicine, indicin, diuretics and we also do surveillance with an echo prior to discharge and also two to three weeks post-op is recommended. In March of 2021 the converged trial was published and this was a prospective multi-center randomized clinical trial that demonstrated improved effectiveness of the hybrid convergent procedure over endocardial ablation alone. The primary effectiveness was freedom from AFib through 12 months and the hybrid convergent procedure showed superior effectiveness compared to endocardial only ablation in patients with advanced atrial fibrillation. It showed that a heart team approach helps improve outcomes in patients with advanced AFib. The converged trial was conducted at 27 sites in the U.S. and U.K. and studied 153 patients with drug refractory, symptomatic, persistent and long-standing persistent AFib. The patients were randomized two to one into the hybrid convergent arm and endocardial catheter ablation alone. Of note the endocardial ablations were in the study were performed only with radiofrequency catheters and no cryoablation. Also in this study the left atrial appendage was not addressed and was not closed by any technique. So the converged trial imposed no limits on the duration of AFib and also allowed patients with substantial left atrial dilation to be included. So it's the only ablation trial to include these patients. The long-standing persistent atrial fibrillation sub-analysis showed excellent results and led to the FDA label for treatment of long-standing persistent atrial fibrillation with this technique. A total of 42% of patients in the trial had long-standing persistent atrial fibrillation and I'll get to these results. Baseline characteristics were similar in each arm. AFib duration was on average close to six years and the left atrial size was approximately four centimeters or greater. Follow-up for this study was done at six and 12 months with a 24-hour Holter monitor and at 18 months with a seven-day Holter monitor. The results showed freedom from atrial arrhythmia with or without anti-arrhythmic drugs was significantly higher approximately 20% better with the convergent approach versus endocardial ablation alone and these results were sustained at 18 months. Freedom from AFib and at least a 90% AFib burden reduction was significantly higher with a convergent procedure versus endocardial ablation alone. These again were sustained through 18 months. The left diagram shows that 71% of patients in the hybrid group had or had freedom from AFib at 12 months compared to about 51% of patients with catheter ablation. At 18 months these results were sustained. The convergent patients also had a significant improvement of up to 71% of all AFib symptoms and freedom from cardioversion compared to 41% for endocardial ablation patients alone at 12 months. The convergent approach was proven to be safe. There were no deaths and one pericardial effusion one stroke and a temporary fredic nerve injury. These primary safety events were not reported in the endocardial ablation arm. So in conclusion there were superior outcomes with a hybrid convergent procedure compared to endocardial catheter ablation alone and those with drug refractory long-standing persistent AFib and these results were sustained at 18 months. There was an acceptable safety profile and it shows that a collaborative heart team approach improves outcomes in patients that are difficult to treat with long-standing AFib. The convergent plus approach which is what I personally perform at Texas Heart Institute and a lot of centers are now going to produces further optimization of the hybrid treatment to reduce stroke risk by closing the left atrial appendage and it provides more AFib burden reduction. It includes the previously described epicardial ablation and the second endocardial ablation of the conversion approach but it adds a left thoracoscopy and epicardial closure of the left atrial appendage typically within a clip. Division of the ligament of Marshall and additional ablation lines on the roof of the left atrium and also at the anterior to the left pulmonary veins and at the base of the appendage can also be added. These basically just add more improvement of freedom from AFib and stroke. Closure of the left atrial appendage is also important because it's often a trigger site for atrial fibrillation and a source of thrombus formation and stroke. Left atrial appendage closure should be an integral part of any AFib treatment. There are several methods for this. I'll talk about the surgical closure. These pictures show the atroclip which is an epicardial surgical placement of a clip at the base of the appendage for complete closure of the appendage. Over 300,000 atroclip devices have been used and it's very safe, effective and easy to use. These images just show a left thoracoscopic view of the left chest. Here we're looking at the pericardium and you can see we make a pericardial window or opening in the pericardium just posterior to the phrenic nerve. After you get into the pericardium the left atrial appendage is seen and can usually be brought out into the pleural space through the pericardial opening and on the right it shows the atroclip after deployment at the base of the appendage. We also use transesophageal echocardiogram at the time of surgery to ensure that the left atrial appendage is completely closed. Closing the appendage is known to down-regulate the renal angiotensin aldosterone system, also reduce arrhythmia burden and most significantly reducing the risk of stroke and systemic thromboembolization. The Laos III study part of that looked at the left atrial appendage occlusion during cardiac surgery to prevent stroke and it was published in the New England Journal in June of 2021. It was a multi-center randomized controlled trial involving patients with AFib and those that had a CHADS VAS score of at least two. A higher score here indicates a greater risk for stroke. This study looked at over 4,000 patients, over 2,000 were in both the surgical occlusion arm and the other arm were those who did not have occlusion of the left atrial appendage. The patients underwent cardiac surgery for other indications and were randomly assigned to either occlusion of the left atrial appendage or no occlusion. The primary outcome showed occurrence of ischemic stroke and systemic embolization were significantly reduced. At 3.8 years the surgical appendage occlusion arm had about 4.8 percent events compared to 7 percent in the group that had no closure of the appendage. So in conclusion, long-standing persistent atrial fibrillation can be successfully and safely treated with a convergent plus hybrid approach. You should always consider surgical ablation, which the gold standard is the COXMase IV procedure and left atrial appendage closure during concomitant cardiac surgery in patients with AFib or as a standalone procedure when it's indicated. A team approach is an excellent way to optimize the treatment and reduce the complications associated with atrial fibrillation. So when managing your patients with atrial fibrillation, don't forget that surgical treatment remains a vital part of the optimal management of AFib and we're always here to help. I want to sincerely thank the Texas Heart Institute and Baylor St. Luke's Medical Center for the opportunity to speak with you today about surgical treatment for atrial fibrillation. Enjoy the rest of the conference. Thank you.