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Venice Chart International Consensus Document on Atrial Fibrillation Ablation: 2011 Update

2012; Wiley; Volume: 23; Issue: 8 Linguagem: Inglês

10.1111/j.1540-8167.2012.02381.x

1540-8167

Antonio Raviele, Andrea Natale, Hugh Calkins, A. John Camm, Riccardo Cappato, Shih Ann Chen, Stuart J. Connolly, Ralph J. Damiano, Roberto De Ponti, James R. Edgerton, Michel Haı̈ssaguerre, Gerhard Hindricks, Siew Yen Ho, José Jalife, Paulus Kirchhof, Hans Kottkamp, Karl Heinz Kuck, Francis E. Marchlinski, Douglas L. Packer, Carlo Pappone, Eric N. Prystowsky, Vivek Y. Reddy, Sakis Themistoclakis, Atul Verma, David J. Wilber, Stephan Willems,

Cardiac electrophysiology and arrhythmias

This Venice Chart International Consensus Document on atrial fibrillation (AF) ablation represents an update of the initial document published in the Journal of Cardiovascular Electrophysiology in 2007.1 Since then, many technological developments and progress have been made and AF ablation has become a well-established, widespread treatment for patients with AF. Over the last decade, ablation of AF has focused on the left atrium (LA) and this has stimulated further investigation on gross and microscopic anatomy of the LA and of the neighboring structures. Knowledge of their architecture and mutual relationships is necessary to access, map, and ablate the LA in a safe and successful way. The anatomy and position of the fossa ovalis are major determinants for the electrophysiologists' ability to safely access the LA through transseptal catheterization. The dimensions of the fossa ovalis (average vertical diameter of 19 mm, average horizontal diameter of 10 mm, thickness of 1–3 mm)2 allow a safe double transseptal puncture. Table 1 reports the congenital or acquired disorders of the chest and cardiovascular structures possibly affecting the location of the fossa ovalis and, therefore, resulting in a more difficult transseptal access. Similarly, multiple previous transseptal catheterizations causing fibrosis of the fossa ovalis are the major variables associated with difficult puncture and penetration of the transseptal needle.3 Transseptal catheterization in the presence of a device occluding the fossa ovalis is possible, because its position is more cranial as compared to the fossa ovalis position.4 However, a careful approach and additional imaging are mandatory. Three-dimensional (3D) imaging of the LA and pulmonary veins (PVs) shows a wide range of variants of their anatomy.5 Specifically, the typical PV branching pattern with 4 distinct PV ostia (Fig. 1C) is present in approximately 20–60%, while a very frequent anatomical variant is the presence of a short or long common left trunk, observed in up to 75–80% of cases. The presence of supernumerary PVs, mainly right middle PV or right upper PV, is reported in 14–25% of cases. The criss-cross of myocardial fibers and the increased thickness of the muscular sleeves at the interpulmunary isthmus between the orifices of the ipsilateral PVs with the possibility of epicardially located intervenous muscular connections (Fig. 1B) may represent the anatomical basis for the complexity to achieve a permanent PV isolation by ablation techniques.6 Another critical structure for ablation procedure is the ridge or carine between LA appendage and left PVs (Fig. 1A). The ridge may be flat, round, or pointed in profile and is 0.5 cm outside PV ostia) circumferential lesions around and outside the PV ostia but over time it was modified with wider (1–2 cm outside PV ostia) circumferential lesions (Fig. 2C). Radiofrequency (RF) energy is applied continuously on the planned circumferential lines, as the catheter is gradually dragged along the line, often in a to-and-fro fashion over a point. Successful lesion creation at each point is considered to have taken place when the local bipolar voltage has decreased by 90% or to <0.05 mV. This technique, as initially designed, did not involve verification of PV isolation (Fig. 2C). Many other centers have adopted this technique, some of which have added circular mapping to verify PV electrical isolation. The key to this technique for PV isolation is delivery of the ablation lesions to the vestibule or "antrum" of the PV, which is the funnel-shaped portion of the LA (or perhaps more accurately the PV) that is proximal to the PV-LA junction or so called "ostium." The antrum includes the entire posterior wall and extends anteriorly to the right PVs on the septum (Fig. 2B). Various tools, according to operator preference, can monitor the identification of this region during the ablation procedure. Selective pulmonary venography is used by many centers to establish the relevant anatomy. Intracardiac echocardiography (ICE) offers a better definition of the LA and proximal PV anatomy and allows localizing catheter position.28Computerized 3D mapping and navigation techniques (Carto, NavX, etc.) are useful means to clarify the anatomy of the region and provide a method of nonfluoroscopic catheter guidance. These techniques might be made more anatomically accurate by registration with other imaging techniques such as magnetic resonance (MR) or computed tomography (CT). Technologies to perform "near real time" imaging in the EP laboratory, such as with rotational angiography, are available and might help to address some of the shortcomings of preprocedural imaging, but to date are still not sufficiently effective to result in widespread adoption. The use of a CMC for PV isolation procedures has become incredibly widespread. For the CMC guided ablation technique, 1 or 2 (double Lasso technique; Fig. 2D)29 CMCs are placed within the ipsilateral superior and inferior PVs or within the superior and inferior branches of a common PV during RF delivery. RF ablation is applied until absence or dissociation of all PV potentials are documented by CMCs within the ipsilateral superior and inferior PVs. RF ablation catheter technologies might include standard tip (e.g., 4 mm), large tip (e.g., 8 mm), and closed or open irrigation. With the use of nonirrigated or closed-irrigation ablation catheter technologies, many centers employed ICE during lesion delivery to assess for the formation of microbubbles30 and to monitor in this way tissue overheating.31 With the use of open-irrigation ablation catheters this is no longer relevant. There has been development of new technologies to assist the operator with PV isolation for AF catheter ablation. Various balloon-based technologies have been under investigation, generally designed specifically to deliver arcs or circumferential lesions at the PVs.32 Such technologies have included the use of cryothermy,33–35 laser,36,37 ultrasound,38–40 and RF energy.41–43 Typically these technologies have employed a noncompliant balloon and have suffered from inability to isolate the PVs proximally, particularly at the antrum, but instead achieve isolation more distally at the ostium of the PV or even within the PV itself.44,45 This latter issue has been the "Achilles heel" of such balloon technologies, as the resulting lesion delivery at such a distal location has been associated with lower efficacy, by not addressing more proximal sites of triggers, and with an increase in complications such as PV stenosis and phrenic nerve damage. Other balloon-based technologies are under development that would employ a compliant balloon to address these shortcomings.37 Another new technology has been the development of catheters with various lengths and shapes of the effective ablation delivery region. With use of such catheters, delivery of arcs or lines of lesions might be facilitated.46,47 Robotic technologies have been developed for use for catheter navigation. Presently, 2 of such technologies are available.48,49 One technology utilizes magnetic fields to navigate special magnetic catheters. The magnetic field can be manipulated at a remote workstation to direct the tip of the catheter. A significant advantage of the magnetic catheter is the physical property of being quite floppy, with virtually no ability to generate excessive contact force against the myocardium to prevent a risk of perforation. This allows for manipulation of the catheter without or at least with much reduced fluoroscopic guidance. A major limitation of this robotic technology is the inability to control additional catheters, such as the CMC and/or the ICE catheter. The use of this magnetic robotic technology for AF catheter ablation has been reported with comparable efficacy and safety to manual techniques.50–52 Another robotic technology that has become available is a system that employs a deflectable sheath controlled at a remote workstation. The primary advantage of this system is the ability to use standard catheters rather than specialized catheters as with the magnetic robotic system. However, this system does not offer the safety of the magnetic catheters with regards to potential for excessive forces to the myocardium, so the risk of perforation remains an issue. Reports from centers with extensive experience has demonstrated comparable results to manual methods and reduced fluoroscopy times.53,54 Different patterns of electrograms have been targeted during radiofrequency catheter ablation of AF.21,55–64 Among these, CFAEs have been most widely studied. In the initial report by Nademanee et al., the definition of CFAE included: (1) atrial electrograms composed of 2 deflections or more, and/or perturbations of the baseline with continuous deflections of a prolonged activation complex over a 10-second recording period, and (2) atrial electrograms with very short cycle lengths (≤120 ms) averaged over a 10-second recording period. Intraoperative mapping of AF has shown that CFAEs are found mostly in areas of slow conduction or at points where the wavelets turn around at the end of arcs of functional block. Such CFAEs have heterogeneous spatial and temporal distribution. Recent studies have attempted to target these CFAEs in order to terminate and prevent recurrence of AF.55,56,61–63,65–67 In the study by Nademanee et al., regarding 121 patients with AF (57 paroxysmal), CARTO mapping of both atria was performed during spontaneous or induced AF. CFAEs were identified using bipolar recordings filtered at 30 to 500 Hz and defined by the presence of voltage ≤ 0.15 mV.55 RF ablation of the area with CFAEs was performed in an attempt to eliminate the CFAEs. According to this report, 92 (76%) of the 121 patients were free of arrhythmia at 1-year follow-up. However, other studies have shown conflicting results with some improvement or no improvement when ablation of CFAEs alone or in combination with PV isolation is performed, in patients undergoing AF ablation.56,61–63,65–67 According to a recent meta-analysis, the addition of CFAE ablation to PV antral isolation increases the rate of sinus rhythm maintenance in patients with persistent and long-lasting persistent AF, but does not provide supplemental benefit in patients with paroxysmal AF.67 Therefore, further randomized studies are needed to clarify the real value of CFAE ablation in patients with AF. Linear lesions were used initially intraoperatively with the aim of preventing the multiple reentrant wavelets that sustain AF. It is not surprising that catheter-based ablation procedures pursued a similar strategy. The goal of linear lesions is the achievement of bidirectional conduction block. Despite the use of irrigated tip ablation catheters with 3D anatomical guidance, lesion creation remains challenging.68 Linear lesions have been reported to be associated with conversion of AF either directly to sinus rhythm or to atrial tachycardia (AT), further demonstrating that such lesions may at least in some patients deeply modify the substrate for AF.69,70 Most of these ATs are macroreentrant and require linear lesions to be treated.71 Such organized tachycardias may be observed during the index procedure or emerge upon follow-up. Although complete linear lesions can terminate such organized tachycardias, the development of a gap in conduction block along such lines has the potential for a proarrhythmic effect and can facilitate sustained reentry.72 For patients in whom atrial flutter has been previously recorded clinically as well as those in whom right atrial flutter is inducible after PV isolation, ablation of the right atrial cavo-tricuspid isthmus73 may be appropriate but on long-term follow-up may be of limited added value beyond PV isolation alone.74,75 Ablation of the posterolateral mitral isthmus (to the inferior pole of the left PV antrum) has been widely deployed in patients with persistent AF.69,76,77 One limitation of the mitral isthmus ablation is that it can require supplemental radiofrequency applications in the distal CS with its intrinsic safety concerns before conduction block is achieved. A number of approaches have been proposed to overcome this requirement, including balloon occlusion of the CS to reduce the heat sink effect of the CS blood flow during endocardial ablation78 and modification of the line to a more supero-lateral trajectory. With wide area circumferential PV antral isolation approach, the distance between the contralateral encirclements is greatly reduced posteriorly. Thus, an LA roof line (which can be created sufficiently superiorly to minimize ablation adjacent to the esophagus) can be achieved with a short transverse lesion connecting the 2 encirclements. More recently the creation of a second transverse linear lesion between the inferior poles of the contralateral encirclements has been deployed in order to complete a box isolation of the posterior LA wall.79 This latter technique has the advantage of isolating a large area of high frequency activity where triggers and drivers are more likely to occur than other parts of the atria. Supplemental linear ablation on the anterior wall of the LA appears to be of lesser potential impact.80 Autonomic influences in the heart are produced by the extrinsic (central) and intrinsic cardiac autonomic nervous systems. The intrinsic cardiac autonomic nervous system contains clusters of autonomic GP located in epicardial fat pads on the left and right atria (superior left GP, inferior left GP, anterior right GP, inferior right GP) and in the ligament of Marshall (Marshall tract GP).81–83 In patients with AF, endocardial high-frequency stimulation (HFS, cycle length 50 ms, 12 Volt actual output, 10 ms pulse width) produces a positive vagal response (transient AV block during AF and hypotension), allowing the identification and localization of left atrial GP. These GP may represent a target of AF ablation. For endocardial GP ablation, RF energy should be applied to each site exhibiting a positive vagal response to HFS.83,84 HFS is repeated after each RF application. If a vagal response is still present, RF energy is reapplied until the vagal response is eliminated. Elimination of the vagal response to HFS at each GP generally requires 3-10 RF applications (usually 30-35-40 Watts for 30–40 seconds but less when close to the esophagus). In a population of 63 patients with paroxysmal AF undergoing ablation of the left atrial GP followed by PV antrum isolation, GP ablation alone (prior to PV antrum isolation) decreased the occurrence of PV firing from 47 of 63 patients (75%) before GP ablation to only 9 of the 63 patients (14%) (P < 0.01) after GP ablation.83 PV antrum isolation was then performed, which eliminated PV firing in the remaining 9 patients (0/63 patients). The description in this and earlier studies of the elimination of PV firing by PV isolation, without targeting the sites of firing,85 may be explained by the interruption of the axons extending from the GP to the PV myocardium. A similar relationship is present between CFAE ablation86 and GP ablation. GP ablation alone often eliminates the majority of CFAE, despite ablating a much smaller area than the overall CFAE area. CFAE ablation may eliminate much of the fractionation by ablating the axons without ablation of the GP cell bodies. Pachon et al. have developed a system for real-time spectral mapping using fast Fourier transform in sinus rhythm.86 This mapping strategy identifies sites in which the unfiltered, bipolar atrial electrograms contain unusually high frequencies, namely fibrillar myocardium or the so-called AF Nest. The investigators successfully targeted biatrial AF Nests, without intentional PV isolation, as a novel approach for AF ablation. Oh et al. compared CFAE sites and AF Nests in an animal model of vagally mediated AF and concluded that these sites did not share identical anatomical locations.87 Typically for AF Nest ablation, RF delivery for 20–30 seconds abolishes the high-frequency potentials normalizing the spectrum. Arruda et al. evaluated the adjunctive role of AF Nest ablation to antral PV isolation and SVC isolation in a prospective randomized study. The adjunct of AF Nest ablation resulted in a 10% decrease of recurrence as compared to conventional antral PV isolation and superior vena cava isolation.88 A stepwise approach has been recently developed in patients with long-lasting persistent AF with different sequences that target multiple atrial areas.89 The endpoint of the sequential ablation strategy is termination of AF. This can be achieved by passing directly from AF either to sinus rhythm or, more commonly, to AT, which is then mapped and ablated. The first step consists in PV isolation using antral isolation. As only 12% of AF will stop at that stage, the second step is frequently needed. It requires ECG-guided ablation targeting continuous electrical activities, focal sources, areas with temporal gradient, etc. The last step uses linear lesions and is used in case of persisting AF/AT after the first 2 steps. The mitral isthmus line is deployed after the roof line as a last resort given the difficulties observed in achieving a complete block. Once sinus rhythm has been restored, PV isolation and linear lesions are checked for completeness and areas re-ablated if needed. It should be emphasized that this approach represents an extensive procedure associated with significant risks and requires careful and individualized risk–benefit assessment. However, it is associated with unprecedented success rate in long-lasting AF, particularly when AF termination is achieved during the index procedure. In order to improve permanent transmural lesion formation, contact force sensing technology (Biosense Webster and Endosense SA) is currently under clinical investigation. The contact force sensor integrates within the distal tip of a conventional mapping and ablation catheter, providing real-time catheter tip-to-tissue contact feedback. Preliminary results using the Endosense catheter demonstrate feasibility and safety in using this new technology for PV isolation.90 Several ongoing studies will determine whether the addition of contact force measurement during AF ablation will result also in improved procedural outcome. An alternative means of contact force assessment utilizes local impedance changes between catheter tip and cardiac tissue. The software integrates with the Ensite NavX electroanatomical mapping system and initial animal and human studies have shown its clinical utility during mapping and ablation within the LA.91,92 The ability to register real-time in-tissue temperature during ablation could potentially facilitate better lesion formation. Using microwave radiometry, very early in-human data demonstrate a correlation between in-tissue temperature and lesion transmurality. Future studies are needed to assess the system's feasibility during AF ablation. The remote magnetic mapping and ablation system by Magnetecs promises real-time catheter maneuverability within a magnetic field of 1.5 Tesla. The system uses 8 electrical magnets that can be switched off. Hence, no magnetic shielding of the examination room is needed. Studies are under way to test the system's mapping capabilities within humans. The Amigo robotic arm by Catheter Robotics can be mounted on any conventional examination table and facilitates remote-controlled movement of mapping and ablation catheters. The system is available in Europe and can be integrated with any electroanatomical mapping system. Clinical data are limited with 1 trial currently recruiting patients to assess the system's ability to navigate and map within the human heart. A new electroanatomical mapping system is currently being developed that uses a basket-shaped mapping catheter to facilitate acquisition of several thousand mapping points within several minutes. Initial clinical data indicate that the system is able to map complex left atrial arrhythmias in humans. The key points regarding the techniques and technologies for AF catheter ablation are reported in Table 4. The principal procedural endpoints used for catheter ablation of AF depend on the type of AF being treated. Endpoints include completion of a predetermined lesion set,93 termination of AF during ablation,89 and noninducibility of AF following ablation.94,95 There is still debate surrounding the predictive value of such endpoints, in particular AF termination. In patients with paroxysmal AF, it is possible that the termination of AF during ablation is coincidental. In these patients noninducib