br Hybrid approach It is still not certain whether a
Hybrid approach It is still not certain whether a single or a staged approach is safer and more effective. Natale et al.  performed a combined closed-chest epicardial monopolar radiofrequency ablation through a transabdominal transdiaphragmatic single port and catheter-based transseptal endocardial ablation as a single-stage approach in 22 patients with long-standing persistent AF and a large left atrium. The outcome and complications were compared with those in patients who underwent standard manual catheter ablation. The hybrid approach resulted in 13.6% mortality rate, whereas no death was reported in the standard approach. There was no significant difference in AF-free rate (55% vs. 54%) after a single procedure. Mahapatra et al.  performed a sequential surgical epicardial ablation followed by planned endocardial evaluation and ablation during the same hospitalization in 15 patients who failed at least 1 catheter ablation and treatment with 1 antiarrhythmic drug, and compared the results with 30 patients who underwent a repeat catheter ablation. Five of the surgical ablation patients were inducible to atrial flutter and were ablated. After a mean follow-up of 21±5 months, 86.7% of the surgical ablation patients were free of atrial arrhythmias and off of antiarrhythmic drugs, compared with 53.3% in catheter-alone patients. More recently, Pison et al.  reported the 1-year follow-up data of 26 patients who underwent a hybrid thoracoscopic surgical and transvenous catheter ablation of AF. Epicardial PV isolation with a bipolar RF clamp was tested endocardially, and 23% of the patients showed residual conduction across the lesion. The lesion set was determined in a stepwise fashion (Fig. 6) and performed epicardially and endocardially. The 1-year success rate for AF was 93% in paroxysmal AF patients and 90% in persistent AF patients.
Challenges for advanced cases A dilated left atrium, a longer duration of AF, the presence of low-voltage f-waves on the electrocardiogram, and others have been reported as risk factors for unsuccessful outcome or AF recurrence after the maze procedure. Damiano et al.  confirmed that an increasing size of the left atrium was a significant risk factor for failure of an ablation-assisted maze procedure, and concluded that there might be a need for a more extensive size JNJ26481585 or expanded lesion sets in patients with a large left atrium. Volume reduction procedures, such as resection of the inferoposterior left atrium  or plication of the redundant left atrium along the PV isolation line , demonstrated an improved conversion rate of AF and increased left atrial function postoperatively. Damiano et al. [34,37] have shown that the box lesion set (Fig. 7), in which the bilateral PV isolation lines are connected at the roof of the left atrium and the entire posterior left atrium is isolated, decreased the incidence of early atrial tachyarrhythmias and late recurrence of AF. Because the more the atrial wall is isolated, the more the atrial transport function is impaired, the indication of the box lesion set should be examined in terms of atrial function in patients with different sizes of the left atrium.
Role of GP ablation Recently, the identification of the GPs and their ablation has been expected to reduce the vagal activity that may facilitate the triggered activity in the PVs and prevent the recurrence of AF after surgical treatment. High-frequency stimulation at a rate of 800beats/min is delivered to the fat pad beside the PVs and atrial tissue; then, a specific area with a vagal reflex (reduction in heart rate) during stimulation is defined as an active GP. Mehall et al.  ablated the GPs in a minimally invasive operation for AF. Forty-one patients with paroxysmal and chronic AF underwent the operation, and on average, 3 active GPs were identified in each patient. More than half of the GPs were found in the area of the superior aspect of the interatrial groove and the ligament of Marshall. In addition to PV isolation, each GP was isolated or ablated, resulting in the complete elimination of vagal reflexes after the ablation. Mcclelland et al.  performed precise mapping of GP activity in 21 patients with paroxysmal or persistent AF. Their data showed that bilateral PV isolation eliminated 79% of the GP active sites and additional GP ablation achieved extensive elimination (94%) of GP activity. During a mean follow-up time of 17±3.5 months, there was only 1 recurrence in a patient with paroxysmal AF, while 4 of 9 patients (44%) with persistent AF had postoperative recurrence. On the other hand, Onorati et al.  reported that GP ablation combined with the maze procedure improved the short-term outcome compared with the maze procedure alone in the treatment of persistent AF during mitral valve surgery.