Thoracoscopic surgical treatment of atrial fibrillation with electrophysiologic end points.

After the seminal observation that reported initiation of AF by pulmonary vein arrhythmogenicity3 and subsequent contributions on pulmonary vein (PV) and non–PV-dependent mechanisms in the genesis of AF, percutaneous catheter ablation has rapidly evolved to eliminate both paroxysmal and persistent AF over the last decade. Numerous reports from registries and randomized clinical trials demonstrated the efficacy, safety, and feasibility of catheter ablation to eliminate AF in appropriately selected patients through the use of well-defined clinical and ECG end points with rigorous long-term follow-up. Given the complexity of the classic cut-and-sew Cox Maze procedure and the skill it requires, surgical treatment of AF has also evolved with an emphasis on (1) less invasive approaches that eliminate the need for a sternotomy and cardiopulmonary bypass, (2) tissue ablation using energy sources similar to those commonly used during percutaneous catheter ablation procedures as an alternative to the challenging and more invasive cut-and-sew technique, and (3) ablation strategies that more or less replicate the lesion sets targeted during percutaneous catheter ablation procedures, primarily on the basis of recent advances in the understanding of the mechanisms of AF.4–9 Although commonly referred as “mini-Maze,” most of the currently used surgical approaches utilize energy sources similar to those used in percutaneous catheter ablation procedures and attempt to create lesion sets to isolate the PVs with additional linear lesions between anatomic landmarks. The use of intraoperative electrophysiologic end points has been variable and often limited to assessment of exit block from the PVs. Reports on the efficacy and safety of this approach with meticulous long-term ECG follow-up, particularly in comparison to catheter-based ablation approaches, have been limited. The study by Krul et al10 in this issue of Circulation: Arrhythmia and Electrophysiology is a timely contribution on surgical ablation of AF. Through a bilateral thoracoscopic approach, PV isolation and ablation of ganglionated plexi (GP) were performed in 31 patients with paroxysmal (n 16) or nonparoxysmal AF (n 15). Antral PV isolation was performed with the use of a bipolar radiofrequency energy clamp. Sites of GP were identified with high-frequency pacing and ablated using bipolar radiofrequency energy. The ligament of Marshall was dissected and ablated in all patients. Additional linear ablation was performed in 13 of 15 patients with nonparoxysmal AF. The left atrial appendage was removed in the majority of patients. Intraoperative electrophysiologic testing was performed to confirm conduction block along these lesion sets and additional ablation was performed to achieve complete block as necessary. An emergent sternotomy was required in 3 of 31 patients for uncontrolled bleeding during the procedure. The other 4 complications included a pneumothorax in 1 patient, a hemothorax in 1 patient, and pneumonia in 2 patients. There were no perioperative mortality or thromboembolic events. The median procedure duration was 205 minutes, with a range of 136 to 540 minutes, and the median duration of hospital stay was 6 days. After a blanking period of 3 months, patients were monitored with a 24-hour Holter and an ECG every 3 months. However, no extended ECG monitoring was performed to look for asymptomatic recurrences of atrial arrhythmias. Freedom from AF was defined as the absence of AF, atrial flutter, or atrial tachycardia 30 seconds in duration. At 1 year of follow-up, 86% of the patients, including 92% of the patients with paroxysmal AF and 80% of the patients with persistent AF, were reported to have remained free from recurrent atrial arrhythmias in the absence of antiarrhythmic drug therapy. The authors should be commended for a meticulously conducted and reported study with attention to detail and consistency in applying the same ablation strategy in similar patients, seeking electrophysiologic criteria as procedural end points, and a follow-up over 1 year. However, there are many questions that remain to be addressed. First, the sample size was very small, limiting the generalizability of the findings to the majority of patients with AF. Second, this was a small, descriptive registry without a control group. Therefore, it is not possible to determine whether each of the specific lesion sets that included ablation of GP, linear ablation, and dissection of the ligament of Marshall was necessary in all patients with AF. It appears that the authors have taken a rather The opinions expressed in this article are not necessarily those of the editors or of the American Heart Association. From the Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI. Correspondence to Hakan Oral, MD, Cardiovascular Center, SPC 5853, 1500 E Medical Center Dr, Ann Arbor, MI 48109-5853. E-mail [email protected] (Circ Arrhythm Electrophysiol. 2011;4:255-256.) © 2011 American Heart Association, Inc.