The goals of treating atrial fibrillation (AF) are to reduce symptoms, to improve and preserve cardiac output by controlling the ventricular rate or restoring and maintaining sinus rhythm, and to reduce the risk of cerebral and systemic thromboembolism. Therapeutic options include rate control with atrioventricular nodal blocking agents such as metoprolol, rhythm control with amiodarone or other antiarrhythmic agents, and catheter-based or surgical ablation along with oral anticoagulation. Due to frequent recurrence, controlling persistent AF is challenging compared with paroxysmal AF. Understanding these unsatisfactory outcomes, our AF team at the Heart and Vascular Institute at the University Hospital and the University of Texas Health Science Center at San Antonio began to consider all the catheter-based ablation and surgical options available to our patients with symptomatic longstanding AF, particularly those with recurrent AF following prior ablation.
Among the catheter-based options we considered were repeat radiofrequency (RF) ablation to ensure electrical isolation of the pulmonary veins, as well as more extensive ablation in the left and right atria, such as ablation of complex fractionated electrograms, ablation of the posterior wall of the left atrium (LA), linear ablation across the LA roof and mitral valve isthmus, and ablation of atrial rotors. Data from recent randomized trials are limited, but suggest that more extensive ablation does not reduce the risk of arrhythmia recurrence compared with pulmonary vein isolation (PVI) alone.1 The current standard for surgical ablation is the Cox-maze IV (CM-IV) procedure, and this extensive ablation has yielded excellent long-term results.2 Surgical ablation also includes the electrical isolation and excision or ligation of the left atrial appendage (LAA), which is known to be the source of emboli in most AF patients suffering from strokes. However, despite its success, we generally reserve the CM-IV procedure for patients undergoing concomitant cardiac surgery, such as coronary revascularization or valve surgery, since it requires sternotomy or thoracotomy and cardiopulmonary bypass with cardioplegic arrest. More recently, we have adopted a hybrid maze procedure for these patients with difficult-to-treat AF. This approach consists of a minimally invasive epicardial maze operation followed by an endocardial ablation one month later. Below we describe a case report to illustrate this procedure, with which we have had encouraging initial results in line with those reported in other series.3
A 74-year-old female was airlifted to the University Hospital in San Antonio after suffering an ischemic stroke. The stroke was treated with intravenous tissue plasminogen activator (tPA), which unfortunately resulted in a small hemorrhagic transformation, but she completely recovered from the stroke. Upon further questioning, the patient described multiple syncopal episodes over the previous year. Telemetry monitoring throughout her hospitalization revealed AF with a rapid ventricular response, sinus bradycardia with ventricular rates as low as 40 beats per minute, and prolonged pauses after spontaneous termination of her AF. Her symptoms of palpitations, dizziness, fatigue, and lightheadedness correlated with the tachycardia and the subsequent conversion bradycardia. Thus, a dual-chamber pacemaker was implanted to prevent recurrent syncope and allow for medical treatment of her atrial arrhythmia with agents that could potentially exacerbate the sinus node dysfunction.
Her lightheadedness and syncope resolved after pacemaker placement, but she continued to experience fatigue and palpitations due to recurrent AF despite treatment with sotalol. These symptoms had been limiting her activities, most notably her ability to enjoy her annual hiking trip to the Adirondacks with her husband. AF with recurrent symptoms, despite treatment with a class III antiarrhythmic, is an indication for catheter ablation. However, periprocedural heparinization is mandated while catheters are maneuvered within the LA. A potential advantage of the hybrid procedure in this case was that minimally invasive epicardial ablation could be performed without anticoagulation, since catheters are never introduced into the heart.
A bilateral video-assisted thoracoscopic surgery (VATS) approach was used for the epicardial ablation. The Isolator Synergy bipolar RF ablation clamp (AtriCure) was used to perform bilateral PVI. Ganglionic plexi were located and ablated using the Isolator multifunctional RF pen (AtriCure), and the Isolator bipolar linear pen (AtriCure) was used to create connecting lines across the roof and floor of the posterior LA wall. An additional lesion was created from the left superior pulmonary vein to the base of the LAA, and the LAA was excluded using the AtriClip PRO device (AtriCure) (Figure 2). She converted to normal sinus rhythm during the procedure.
Endocardial interrogation of the veins and LA as well as a cavotricuspid isthmus (CTI) line was performed four months after the epicardial ablation. During the epicardial mapping procedure, interrogation of the pulmonary veins with a Reflexion Spiral catheter (St. Jude Medical) demonstrated lack of pulmonary vein potentials. Electrical isolation of the pulmonary veins was also supported by the presence of scar or electrical potentials of less than 0.5 mV at the left atrial/PV junctions during voltage mapping with the EnSite Velocity System (St. Jude Medical) (Figure 1). One month later, our patient was once again hiking along the steep trails of Lost Maples State Natural Area. “They’ve basically given me my life back,” she wrote in a postcard.
We usually consider a hybrid epicardial and endocardial ablation for patients with symptomatic longstanding AF who have either recurrence following catheter ablation or are at increased risk of recurrence due to dilated left atria (>5 cm) or longer duration of AF. Exclusions include previous cardiac surgery and severe lung disease that would preclude single-lung ventilation. This case was atypical in that endocardial catheter ablation was deferred because of the patient’s recent ischemic stroke with hemorrhagic transformation. Endocardial ablation would have required intense periprocedural anticoagulation, which we felt would not be safe given the temporal proximity to her hemorrhagic stroke. Due to the severity of her symptoms, we chose to proceed with an epicardial ablation as opposed to waiting to perform an endocardial ablation once the intracranial bleeding risk was acceptable. This case is also different in that the second procedure was delayed until four months after the epicardial ablation. As noted above, we tend to wait one month between procedures to ensure complete electrical isolation of the pulmonary veins. Endocardial mapping is critical to the success of the hybrid ablation, as the endocardial approach ensures transmurality of the lesions. In this case, pulmonary vein potentials were absent and scar was noted at each antrum (Figure 1).
There are several unresolved issues surrounding hybrid ablation for AF. Small series have shown one-year freedom from AF as high as 90%.3 However, the authors do not always use a standard definition of success, and there is no consensus regarding the management of post-operative antiarrhythmic medications or anticoagulation. We generally discontinue amiodarone one month after the endocardial ablation if there is no evidence of recurrent AF. We have been continuing oral anticoagulation unless contraindicated, preferably with novel oral anticoagulants, but many centers switch to an aspirin-only regimen after three months of sinus rhythm. Lastly, there remains variability in the timing between the epicardial and endocardial ablation procedures, with the two being performed anywhere from the same setting to three months apart. Further studies will help to answer these questions, but it appears that by combining the VATS epicardial ablation with a catheter-based endocardial ablation in a hybrid approach, we are able to achieve results that parallel those of the gold standard, the CM-IV procedure.
Acknowledgements. We appreciate the expertise of Natasha Inamdar, B.S.E. and Jamie Lou, B.S.E., EP Technical Service Specialists from St. Jude Medical in St. Paul, MN, for creating the three-dimensional voltage maps and figures for this report.
Disclosures: The authors have no conflicts of interest to report regarding the content herein.
- Verma A, Jiang C, Betts TR, et al. Approaches to catheter ablation for persistent atrial fibrillation. N Engl J Med. 2015;372:1812-1822.
- Lawrance CP, Henn MC, Damiano RJ, et al. Surgery for Atrial Fibrillation. Heart Fail Clin. 2016;12(2):235-243.
- Gelsomino S, Breugel H, Pison L, et al. Hybrid thoracoscopic and transvenous catheter ablation of atrial fibrillation. Eur J Cardiothorac Surg. 2014;45(3):401-407.