In a revised consensus statement for AF surgery
In 2012, a revised consensus statement for AF surgery was published by the Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society as a part of the “Expert consensus statement for catheter and surgical ablation for AF” . The statement was focused mainly on the relief of symptoms associated with AF and the safety of the procedure, as shown in Table 1.
The consensus conference of the International Society of Minimally Invasive Cardiothoracic Surgery (ISMICS) aimed to determine whether surgical AF ablation during cardiac surgery improves the clinical and resource outcomes compared with cardiac surgery alone in adults undergoing cardiac surgery for valve or coronary artery bypass grafting [8,9]. The available evidence, including systematic reviews, randomized trials, and nonrandomized trials, was reviewed by the consensus panel and considered in descending order of validity and importance. Then, evidence-based statements were created and consensus processes were done to determine the ensuing recommendations. Six questions were formulated and statements were drawn for each question, except for question 6, as shown in Table 2. Although the evidence level was B and the class of recommendation was IIa, the consensus panel reached an agreement that possible a concomitant surgical ablation is recommended to reduce the risk of stroke and thromboembolic events and improve the long-term survival of patients (Fig. 2).
Surgery for failed catheter ablation for lone AF Although most patients with paroxysmal AF are effectively treated by catheter ablation, one or more additional sessions of ablation are required in some of these patients and in a considerable number of those with persistent or long-standing persistent AF. Ad et al.  performed the maze procedure in 40 patients with recurrent AF who underwent at least one left-sided ablation. Ninety-five percent of the patients presented with long-standing persistent AF. Careful inspection of the left atrial endocardial surface revealed multiple spots of scar tissue, but with no definite linear or continuous scar formation. At the time of the operation and before surgical ablation, 96 PVs were assessed for an exit block. Ninety-five percent of the veins tested were found to conduct across the ablation line, even though all tested veins had a documented confirmed conduction block at the time of percutaneous catheter ablation. After the maze procedure, the sinus rhythm was maintained in 76%, 89%, and 93% of the patients during the follow-up periods of 6, 12, and 24 months, respectively, without taking class I/III antiarrhythmic drugs (Fig. 3).
Minimally invasive surgery for lone AF The minimally invasive surgical procedure was developed for patients with lone AF without any structural heart disease. The procedure includes PV isolation with or without connecting lesions, excision or closure of the left atrial appendage, or ablation of the active GP, performed through small thoracotomy or a thoracoscopic approach. This procedure avoids the use of cardiopulmonary bypass, cardiac arrest, and a full sternotomy. Initially, the indication of the minimally invasive procedure was paroxysmal AF; however, more recently, it has been extended to persistent and long-standing persistent AF . Nevertheless, PV isolation alone has been shown to be insufficient in treating long-standing persistent AF, and the need for connection lines between the PV isolation lines and the mitral annulus has been raised . Various epicardial techniques were tested to create a linear block line on the atrial free wall on the beating heart [13–16]. Compared with the full-maze procedure with cardiopulmonary bypass, cardiac arrest, and full sternotomy, the minimally invasive procedure reduces the potential risk of bleeding, myocardial damage and other complications, and mortality. PV isolation can be performed both with catheter ablation and surgical ablation. Sauren et al.  investigated the occurrence of cerebral microembolic signals as a surrogate marker for the risk of neurological impairment of 2 different PV isolation methods: percutaneous endocardial RF ablation and thoracoscopic epicardial ablation with RF energy.