The Convergent Procedure for AF: Experience at Allegheny General Hospital

Case Description

The patient is a 51-year-old male with a history of hypertension, obesity, hyperlipidemia, and longstanding symptomatic persistent atrial fibrillation (AF) of approximately two years duration. He had previously undergone multiple cardioversions and experienced recurrent AF despite amiodarone therapy. He was referred to our institution for further therapy. His preoperative ECG (Figure 1) showed AF and left axis deviation. Transesophageal echocardiogram (TEE) was performed and showed a dilated left atrium (LA) with no thrombus, no significant valvular abnormalities, and a normal-sized left ventricle with an ejection fraction of 50%. Cardiac CT confirmed LA enlargement with LA volume of 233 cc and an AP dimension of 6.9 cm. Because of his symptomatic, longstanding persistent AF as well as his severely dilated left atrium, a convergent pulmonary vein isolation (PVI) procedure was recommended. 

His convergent ablation was performed in July 2012 in our combined EP/convergent surgical suite. His anticoagulation with dabigatran was discontinued 24 hours before the procedure. Epicardial posterior LA ablation was performed first by cardiothoracic surgeon Dr. Moraca using a subxiphoid, thorascopic, transdiaphragmatic approach. Radiofrequency (RF) ablation was performed between the left and right pulmonary veins using a 3 cm unipolar ablation catheter (Figure 2). A standard catheter-based PVI was then performed by electrophysiologist Dr. Belden immediately after the epicardial posterior LA ablation was completed. Endocardial LA voltage mapping confirmed extensive posterior LA ablation (Figure 3). Electrogram-guided PVI was then performed using a circular mapping catheter and an irrigated RF ablation catheter. Conversion to sinus rhythm occurred with isolation of the final pulmonary vein (Figure 4). Figure 5 shows the post-PVI LA voltage map from a posterior superior angle with endocardial ablation lesions depicted in red. Challenge with high-dose isoproterenol and atrial burst pacing to 200 msec failed to induce any atrial arrhythmias. The patient tolerated the procedure without complication, and was admitted to the surgical intensive care unit for recovery.

His post-operative course was uncomplicated except for mild pericarditis, which was treated with intravenous steroid therapy. He remained in normal sinus rhythm and was discharged home on postoperative day 2. His amiodarone therapy was discontinued at the three-month postoperative visit, and a 14-day Holter monitor and EKG at the six-month post-operative visit showed normal sinus rhythm with no atrial arrhythmias. He denied any symptoms of recurrent AF following his procedure. Dabigatran was discontinued at six months and daily aspirin therapy was initiated. A post-operative CT scan was obtained at six months, which showed no PV stenosis and indicated that his left atrial volume had decreased to 201 cc from 233 cc and the AP dimension had decreased to 5.9 cm from 6.7 cm. A 12-lead EKG performed nine months after the procedure showed normal sinus rhythm (Figure 6). Clinically he reports dramatic improvements in his exercise capacity and quality of life.

Discussion

While no consensus currently exists in the electrophysiology community as to the best ablation approach for persistent AF, we believe that substrate ablation in addition to standard PVI is important for maintenance of sinus rhythm in this population. We believe that thorough substrate modification of the posterior wall of the left atrium contributes to the success rate of this convergent procedure. Possible mechanisms of this success include electrical debulking of the left atrium, ablation of focal drivers or rotors responsible for perpetuating AF, as well as ablation of ganglionated autonomic plexi found on the epicardial surface of the left atrium. The convergent procedure takes advantage of skills brought to the table by both the cardiothoracic surgery and electrophysiology teams. Substrate modification of the left atrium is performed in a thorough, efficient, and safe manner by the cardiothoracic surgeon as a result of the larger catheter and its unidirectional ablation performed under direct visualization. Because pericardial reflections do not allow epicardial access to all aspects of the left atrium, endocardial ablation is necessary to achieve and confirm bidirectional block of the pulmonary veins. Mapping and isolation of the remaining pulmonary vein potentials and ablation of other arrhythmias such as atrial flutters and focal atrial tachycardias are best addressed by the electrophysiologist with standard techniques. 

Our experience at Allegheny General Hospital with the convergent procedure has been very favorable as depicted in the case presented and many other similar patients. We recommend the convergent procedure for all patients with longstanding persistent AF and dilated left atria. To date, we have performed the hybrid procedure on 50 patients at our institution. Fourteen-day cardiac event monitoring has been performed at six and 12 months post procedure. We have observed a high rate of sinus rhythm maintenance off antiarrhythmic therapy of approximately 80% at 12 months, with a very low complication rate. Post-operative pericarditis has been the most common complication, and all patients with pericarditis have responded to treatment with NSAIDs and/or steroids without recurrence. Longer term follow-up and randomized studies comparing hybrid ablation to catheter ablation in longstanding persistent AF are required. 

Disclosures: Dr. Belden reports he has received honoraria for training from nContact. Dr. Moraca reports consultancy (training) with AtriCure. 

Next month EP Lab Digest^® will feature part two of this case series from M. Clive Robinson, MD at Bridgeport Hospital.