7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate Official reprint from UpToDate www.uptodate.com 2023 UpToDate, Inc. and/or its affiliates. All Rights Reserved. Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists : Rod Passman, MD, MSCE : Bradley P Knight, MD, FACC, N A Mark Estes, III, MD : Nisha Parikh, MD, MPH All topics are updated as new evidence becomes available and our peer review process is complete. Literature review current through: Jun 2023. This topic last updated: Jun 13, 2022. INTRODUCTION The primary trigger for most episodes of atrial fibrillation (AF) is an electrical discharge(s) within one of the four pulmonary veins (see "Mechanisms of atrial fibrillation", section on 'Triggers of AF'). The cornerstone of any procedure aimed at reducing AF burden is the electrical isolation of the pulmonary veins so that these discharges do not trigger the initiation of AF. In those with persistent and longstanding persistent AF, and in some patients with paroxysmal AF, additional areas, often in one or both of the atria or surrounding structures, are targeted for ablation, as they may also serve as a source of AF triggers or maintenance. Catheter ablation (CA) is the procedure that is used to prevent the initiation of AF by electrically isolating these triggers from the rest of the atrial chamber tissue. This topic is intended to be viewed primarily by non-electrophysiologists. Electrophysiologists may be more interested in other topics: (See "Overview of catheter ablation of cardiac arrhythmias".) (See "Maintenance of sinus rhythm in atrial fibrillation: Catheter ablation versus antiarrhythmic drug therapy".) (See "Atrial fibrillation: Catheter ablation".) (See "Invasive diagnostic cardiac electrophysiology studies".) https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 1/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate (See "Catheter ablation to prevent recurrent atrial fibrillation: Anticoagulation".) PATIENT SELECTION A major clinical goal of CA is a reduction in AF-related symptoms. CA is superior to medical therapy at improving quality of life. Therefore, it is generally reserved for individuals with symptoms attributable to the arrhythmia, which most often include palpitations, shortness of breath, or generalized fatigue [1,2]. Even if they have no AF-related symptoms, older individuals with early AF (duration <1 year) and additional cardiovascular conditions also benefit from therapies aimed at maintaining sinus rhythm; these therapies include CA [3]. (See "Maintenance of sinus rhythm in atrial fibrillation: Catheter ablation versus antiarrhythmic drug therapy", section on 'Recommendations of others'.) Patients should be considered for ablation for AF after the history and physical exam have been reviewed and there is documentation of symptomatic correlation with AF on electrocardiogram (ECG) or other forms of monitoring. Modifiable risk factors including obesity, excessive alcohol intake, and sleep apnea should be addressed, as they are important components of AF treatment and impact the success of any rhythm control intervention [4-8]. AF CA may be appropriate in the following groups: Patients with paroxysmal or persistent AF who have tried a class I or III antiarrhythmic drug ablation can be considered if such medications are either unsuccessful or are not tolerated. Some individuals may choose ablation as first-line therapy. For patients with long-standing persistent AF, a trial of one or more class I or III antiarrhythmic drugs is recommended. Ablation as first-line therapy can be considered in those with contraindications to drugs. Asymptomatic younger individuals and patients with heart failure due to reduced ejection fraction may also benefit from ablation [9,10]. We do not perform CA in: Individuals who are too frail to safely undergo the procedure. Patients with a left atrial appendage thrombus. Individuals with bleeding diathesis who cannot receive intra- and postprocedural anticoagulation. PREPROCEDURAL PREPARATION https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 2/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate Once a patient has been selected for AF ablation, the clinician performing the procedure or their designee should obtain informed consent from the patient. This involves shared decision- making after discussing the indications, benefits, risks, and alternatives of the planned procedure. Sedation options include general anesthesia that requires an endotracheal tube or monitored anesthesia care with sedation but not requiring intubation. Most procedures are performed under general anesthesia. Medication management Most physicians performing ablation will discontinue antiarrhythmic drugs prior to the ablation with the rationale that it may help to identify the triggers of the AF at the time of the procedure. We acknowledge that many other electrophysiologists will continue them. There are no well-performed studies to guide practice. With regard to oral anticoagulation, randomized trials have demonstrated superior efficacy and safety of uninterrupted anticoagulation throughout the ablation procedure compared with temporary discontinuation of anticoagulation and bridging with low molecular weight heparin. Most operators, including the authors, perform the procedure on uninterrupted or minimally interrupted direct-acting oral anticoagulants (DOACs) or vitamin K antagonists (VKAs) such as warfarin. A meta-analysis of 17,434 patients from 12 observational trials and one randomized trial compared uninterrupted warfarin with interrupted warfarin and heparin bridging at the time of AF ablation. Uninterrupted warfarin was associated with significant reductions in stroke and major and minor bleeding [11]. Studies have shown that patients on uninterrupted DOACs have either lower (dabigatran, edoxaban [12,13]) or similar (rivaroxaban, apixaban) [14,15] bleeding risks compared with those on uninterrupted VKA. Studies of DOACS with lower bleeding risks compared with VKA: The RE-CIRCUIT trial randomized 704 patients undergoing AF ablation to uninterrupted dabigatran or VKA. The incidence of major bleeding events during and up to eight weeks after ablation was lower with dabigatran than with warfarin (1.6 versus 6.9 percent) [12]. In a trial of 614 patients undergoing CA, participants were randomly assigned to uninterrupted edoxaban or VKA. Major bleeds were nonsignificantly lower in persons assigned to edoxaban compared with VKA (0.2 versus 2 percent; hazard ratio 0.16; 95% CI 0.02-1.73) [13]. Studies of DOACS with similar bleeding risks compared with VKA: https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 3/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate In a trial of rivaroxaban or VKA in people undergoing AF ablation, bleeding events were similar in the two study arms [14]. In a trial that compared uninterrupted apixaban with placebo, the rates of clinically significant and major bleeding were also similar for both groups (10.6 versus 9.8 percent) [15]. Imaging All patients with AF, not just those being considered for CA, should undergo transthoracic echocardiography (TTE) to evaluate for factors that may affect treatment including the presence and extent of valvular disease, chamber size, and ventricular function. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation", section on 'Echocardiogram'.) Transesophageal echocardiography (TEE), which is superior to TTE for finding atrial thrombus, is often performed within 24 hours prior to ablation since the presence of thrombus in the left atrium or left atrial appendage is a contraindication to AF ablation. Some operators may choose to forego TEE in patients with a low risk of stroke (ie, CHA DS -VASc 1) who are expected to be 2 2 in sinus rhythm at the time of the procedure and who have been and will be maintained on uninterrupted anticoagulation throughout the periprocedural timeframe. Some operators will individualize the need for preprocedure TEE and tend to only perform it in higher-risk patients. Risk factors for left atrial appendage thrombus prior to ablation include hypertrophic cardiomyopathy, ejection fraction <30 percent, persistent or longstanding persistent AF, and elevated CHA DS -VASc score [16]. In a study of 1058 preprocedure TEEs, the rate of detection of 2 2 left atrial thrombus or prethrombus was 1 percent in patients with paroxysmal AF in sinus rhythm and 2 percent for patients with paroxysmal AF who were in AF at the time of the procedure. The risk increased with increasing CHADS score [17]. 2 Computed tomography (CT) or cardiac magnetic resonance imaging (cMRI) may be performed preablation to define the left atrial anatomy, specifically the number, size, and location of the pulmonary veins ( figure 1). Data are emerging to suggest that these imaging techniques are also highly sensitive for left atrial thrombus, and many operators use CT or cMRI to evaluate for left atrial thrombus instead of TEE in low-risk individuals. A comparison of cMRI with TEE to evaluate preablation left atrial appendage thrombus demonstrated 100 percent sensitivity and 99.2 percent specificity for equilibrium phase delayed enhancement CMR with a long inversion time [18]. New high-dimensional mapping catheters used during the procedure can create high- definition structural geometry, and for many operators has obviated the need for preprocedure imaging. PROCEDURAL ISSUES https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 4/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate Ablation for AF is among the most complicated procedures performed by electrophysiologists. The procedure should be performed in centers with experience with complex electrophysiologic procedures and capabilities in managing acute complications. Advancements in procedural technologies and techniques have significantly shortened the duration of ablation procedures for AF. Total procedure time typically ranges from 1.5 to 4 hours [19]. The ablation is performed using uni- or bilateral femoral venous access and transseptal puncture for accessing the left atrium. Anesthesia Ablation for AF is performed in the fasting state with general anesthesia or monitored anesthesia care (MAC) using sedation. In a retrospective cohort study of CA performed under either general anesthesia or conscious sedation, conscious sedation had shorter total procedure times and equivalent success rates compared with general anesthesia [20]. In a retrospective cohort study of CA performed under either general anesthesia or MAC, MAC had shorter total procedure times and equivalent success rates with general anesthesia [19]. Agents typically used for conscious sedation include short-acting benzodiazepines (eg, midazolam) and opioids (eg, fentanyl) in divided doses [21]. The type of anesthesia used for AF ablation procedures is dependent on several variables including the expected complexity and duration of the procedure, energy source being utilized, patient comorbidities, patient preference, and availability of anesthesia support. Patient immobility is important to optimize catheter contact and reduce movement error in the anatomic mapping systems. Paralytics should not be used when testing for phrenic nerve capture during ablation. High frequency ventilation, also called jet ventilation, which utilizes a respiratory rate greater than four times the normal value. (>150 [Vf] breaths per minute) and very small tidal volumes, is used in some centers to aid catheter stability and has been associated with improved outcomes [22]. Intraprocedural medications In addition to anesthetic agents, intravenous heparin is administered throughout the AF ablation procedure to reduce the risk of thrombus formation on the catheters, sheaths, left atrium and left atrial appendage, and at ablation sites. Heparin is administered prior to or immediately after transseptal access has been achieved with a targeted activated clotting time (ACT) of >300 seconds. Target ACT may be reached faster and with lower loading doses in patients undergoing ablation on uninterrupted vitamin K antagonists (VKA) compared with non-vitamin K antagonist oral anticoagulants (NOACs; also referred to as direct acting oral anticoagulants [DOAC]) [23]. Additionally, time to target ACT varies amongst the NOACs, with average time in minutes required to achieve a target ACT of >300 seconds https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 5/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate significantly longer in those receiving uninterrupted dabigatran or apixaban compared with those receiving rivaroxaban [24]. Protamine can be used to reverse anticoagulation at the time of sheath removal post-procedure. Esophageal imaging and temperature monitoring The proximity of the esophagus to the posterior left atrium makes it susceptible to thermal injury (see 'Complications' below). Atrioesophageal fistula, typically occurring one to four weeks post-ablation, is a potentially lethal consequence of AF ablation, with a reported incidence of 0.02 to 0.11 percent. To minimize risk, operators will limit energy delivery in the posterior wall in areas adjacent to the esophagus. As the esophagus can have a highly variable position that can vary throughout the procedure, visualization of the esophagus can be performed using electroanatomic mapping, intracardiac ultrasound (ICE), or barium paste. Many operators use an esophageal temperature probe to assess the effects of ablation on intraluminal temperature, though this practice has not yet been shown to reduce the risk of fistula formation given the low incidence of these events. Given the very low overall incidence of fistula, there have been no randomized data to demonstrate superiority of one esophageal monitoring strategy over another. Consequently, minimization of power delivery to the atrial tissue adjacent to the esophagus or minimization of temperature elevation remain surrogates for procedural safety Vascular ultrasound CA for AF requires multiple sheaths with large diameters in one or both femoral veins in patients receiving oral and intravenous anticoagulation. These issues make vascular complications the most common complications of AF ablation. Access can be obtained through the modified Seldinger approach. Vascular ultrasound has been used for venipuncture guidance and postprocedural evaluation. In a cohort study of 1435 patients undergoing cryoballoon ablation for AF, major clinical events occurred in 1.7 percent of those patients who had their procedure performed without ultrasound guidance versus 0 percent in those that did have ultrasound guidance [25]. In a multicenter, randomized trial, 320 patients were randomized to ultrasound guided versus conventional venipuncture. Major complications were low and not significantly different between groups. Puncture time, inadvertent arterial puncture, and need for extra puncture attempts were all significantly reduced in the ultrasound arm [26]. Intracardiac ultrasound Intracardiac ultrasound allows for real-time imaging of cardiac anatomy. The probe is placed in the right atrium via the inferior vena cava. Common uses of ICE include the identification of intra- and extracardiac anatomic structures such as the esophagus, facilitation of transseptal puncture, guidance of catheter placement, and recognition of https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 6/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate complications including thrombus formation on sheaths and catheters and early recognition of pericardial effusion. Fluoroscopy Mapping and ablation of AF requires precise navigation of catheters within the left atrium and localization of intra- and extracardiac structures. Fluoroscopy is used to assess catheter placement, to visualize catheter movement, and to assess proximity to adjacent structures such as the esophagus when marked by an intraluminal catheter or barium paste. Patient and physician exposure to ionizing radiation during AF ablation are highly variable, and radiation injury to the patient is reported in <0.1 percent of cases. Efforts to reduce patient and physician exposure to ionizing radiation have successfully relied on alternative imaging modalities, including ICE and electroanatomic mapping. (See "Radiation-related risks of imaging".) Electroanatomic mapping Electroanatomic mapping systems combine real-time, detailed information of the anatomy and electrical properties of the cardiac structures under evaluation. These systems (Carto [Biosense Webster], NAVX [Abbott], and Rhythmia [Boston Scientific]) use diagnostic and ablation catheters and navigation patches on the patient's skin to create a three- dimensional anatomical map used to help localize critical sites for ablation. ABLATION TECHNIQUES AND TARGETS Energy sources There are three US Food and Drug Administration (FDA)-approved energy sources for AF ablation: radiofrequency energy, cryothermal energy in the form of cryoballoon, and laser balloon. This issue is discussed in detail elsewhere. (See "Overview of catheter ablation of cardiac arrhythmias", section on 'Energy sources used for ablation'.) The commonly used and approved energy sources for CA are radiofrequency and cryothermal. The efficacy and safety associated with these two energy sources have been found to be similar in multiple studies. This issue is discussed elsewhere. (See "Atrial fibrillation: Catheter ablation", section on 'Comparison of radiofrequency and cryothermal ablation'.) Pulmonary vein isolation Complete electrical isolation of all PVs using circumferential, wide area pulmonary vein isolation (PVI) is the goal of most procedures. The following explains the rationale. The initiation of AF requires a trigger either within or near the atrium (eg, PVs, crista terminalis, superior vena cava), and substrate within the atrium to maintain AF [9] (see "Mechanisms of atrial fibrillation", section on 'Basic atrial electrophysiology'). The anatomic significance of https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 7/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate triggers and substrate differs somewhat, depending upon whether the AF is paroxysmal, persistent, or permanent (see "Paroxysmal atrial fibrillation", section on 'Introduction'). In patients with paroxysmal AF, PV triggers are the primary stimulus in most cases. As AF becomes more persistent, non-PV sources become more important [27]. The following important observations regarding triggers came from early studies of patients with paroxysmal AF and have guided the development of successful ablation techniques for AF [28-30]. AF is commonly triggered by ectopic beats from muscle fibers (fascicles) extending from the left atrium into the PVs ( figure 1). Ectopic foci are localized to the PVs in approximately 90 percent of patients with predominantly structurally normal hearts [31]. Most patients have multiple foci that can act as triggers. Most (94 percent) of the foci are 2 to 4 cm inside the PVs, with the left superior vein being the most common site [28]. The remaining foci are usually in the right or left atrium. The superior vena cava is a much less common site of triggering ectopic beats [28]. Because of these observations, early attempts at ablation targeted these focal ectopic beats within the PV [28]. This approach was limited by: Inconsistent ability to identify the triggering beats during electrophysiology study. Difficulties with precise localization of appropriate ablation sites. The risk of PV stenosis, which can occur following ablation within the PVs. (See "Atrial fibrillation: Catheter ablation".) These limitations lead to the adoption of ablative techniques focused on the complete electrical isolation of all PVs using circumferential wide area PVI. The majority of ablations performed use radiofrequency energy or cryothermy (cryoballoon ablation). Infrared laser received FDA approval in 2018. Circumferential PVI involves the creation of confluent ablation lesions that encircle the ostia of all four PVs, usually in two pairs (ie, a left- and right-sided circles) [32-34]. The goal is to electrically isolate the PVs from the left atrium. For ablation using radiofrequency energy, power, duration, and the catheter contact force determine the size and the depth of the lesion created. It is generally felt that some lesions create edema but not scars, leading to temporary but not permanent ablation, and this ultimately leads to electrical reconnection of the left atrium to the https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 8/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate PVs. Greater power, longer duration, and greater contact force improve the efficacy of the procedure but lead to an increase in complications such as cardiac perforation [35,36]. The efficacy and safety of high-power, short-duration ablation, which creates larger, shallower, and more homogeneous lesions, is under evaluation [37]. Circumferential PVI results in extensive ablation across a wider area of the left atrium. Because of the more extensive ablation, this technique may provide additional methods for preventing AF, including autonomic denervation, elimination of triggering foci outside the PVs, and alteration of the left atrial substrate necessary for perpetuating AF. However, more extensive ablation, particularly in the posterior left atrium, may increase the rate of complications, including the development of left atrial tachycardias or flutters months or years after the ablation. The relative efficacy and safety of these methods are discussed elsewhere. (See "Atrial fibrillation: Catheter ablation", section on 'Efficacy'.) Use of a contact force-sensing catheter We use a contact force-sensing catheter in all patients with AF undergoing radiofrequency CA (RFA). The TOCCASTAR study found that patients who underwent CA with this catheter and who received a higher force ( 10 grams) had significantly lower rates of AF recurrence at one year. Use of adenosine-guided pulmonary vein isolation The administration of intravenous adenosine can be used to unmask dormant conduction at the time of CA. Reconnection rates are high in RFA, with three large studies finding rates of 21 (ADVICE), 27 (UNDER-ATP), and 34 percent [38-40]. The use of adenosine to guide additional CA has been shown to improve arrhythmia-free survival in some studies using RFA. Some technical aspects of the procedure are discussed separately. (See 'Ablation techniques and targets' above.) In the ADVICE study, 534 patients with paroxysmal AF who had failed drug therapy underwent a standard PV isolation procedure using radiofrequency energy [38]. Patients were observed for spontaneous recovery of conduction over 20 minutes to allow for reconnected PVs to be reisolated before adenosine administration. Intravenous adenosine was then given to all patients. The 284 patients in whom dormant conduction (evidence of persistent PV conduction) was unmasked by adenosine were randomly assigned to additional adenosine-guided ablation to abolish dormant conduction or to no additional ablation. Among the 250 patients without dormant conduction, 117 were enrolled in a registry. The primary endpoint of the time to first recurrence of symptomatic electrocardiographically documented atrial tachyarrhythmia was between 91 and 365 days. The following findings were noted: Dormant PV conduction was present in 284 (53 percent) of patients. https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 9/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate Freedom from symptomatic atrial tachycardia occurred more often with adenosine-guided further ablation (69.4 versus 42.3 percent; hazard ratio [HR] 0.44, 95% CI 0.31-0.64). Among patients in the registry, approximately 56 percent remained free from symptomatic atrial tachyarrhythmia. The rate of serious adverse events was similar in both groups. Limitations of this study include lack of generalizability (does not apply to patients undergoing cryoablation), lack of use of force-sensing catheters, which are used by many of our experts, and the use of "dormant connection" as an endpoint rather than AF recurrence. In the UNDER-ATP trial, 2113 patients with paroxysmal, persistent, or long-lasting AF were randomly assigned to either adenosine-guided PV isolation (1112 patients) or conventional PV isolation (1001 patients) [39]. The primary endpoint was recurrent atrial tachyarrhythmias lasting for >30 seconds or those requiring repeat ablation, hospital admission, or usage of Vaughan Williams class I or III antiarrhythmic drugs at one year with the blanking period of 90 days post-ablation. Among patients assigned to adenosine-guided PV isolation, adenosine provoked dormant PV conduction in 307 patients (27.6 percent). Additional radiofrequency energy applications successfully eliminated dormant conduction in 302 patients (98.4 percent). At one year, 68.7 percent of patients in the adenosine-guided PV isolation group and 67.1 percent of patients in the conventional PV isolation group were free from the primary endpoint, with no significant difference (adjusted HR 0.89; 95% CI 0.74-1.09; p = 0.25). The results were consistent across all the prespecified subgroups. Also, there was no significant difference in the one-year event-free rates from repeat ablation for any atrial tachyarrhythmia between the groups (adjusted HR 0.83; 95% CI 0.65-1.08; p = 0.16). Based on these studies, the use an adenosine in patients undergoing CA with radiofrequency energy is at the discretion of the operator. Confirmation of complete isolation Unlike many other cardiac ablation procedures, AF does not need to be present or induced at the time of the ablation procedure nor is termination of AF or inability to reinduce the arrhythmia a required endpoint of the procedure. For PVI, acute procedural success is defined as electrical isolation of all PVs [41]. This is defined by entry block or the inability to electrically capture PV myocardial tissue distal to the area of ablation when pacing is performed proximal to the ablation line. To do this, a circular catheter is positioned just distal to the PV ostium for the purpose of recording electrograms within the PVs. Confirmation is attempted after a 30-minute waiting period after isolation. https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 10/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate Some operators also test for exit block, defined by the inability to capture atrial myocardium when pacing is performed within the PV distal to the ablation line. There is a high correlation between AF recurrences and the demonstration of persistent or recurrent conduction between the PVs and left atrium (see "Atrial fibrillation: Catheter ablation", section on 'Efficacy'). Recurrent PV conduction explains most cases of recurrence; it is thought to be due to recovery of function of tissue that has been acutely injured (ie, edema and inflammation) but not permanently scarred. Administration of adenosine has been shown to identify PVs with dormant conduction by transiently restoring excitability and conduction across circumferential ablation lines at risk of reconnection [38]. However, improvements in ablation tools and techniques have significantly reduced the routine use of adenosine. It is used at the discretion of the operator. (See "Atrial fibrillation: Catheter ablation", section on 'Efficacy'.) Ablation targets in persistent atrial fibrillation In contrast to patients with paroxysmal AF, patients with persistent AF (and in particular longstanding persistent AF) often have multiple triggers distributed throughout the atria in addition to triggers within the PV [42]. It is thought that mechanisms that maintain rather than trigger the arrhythmia are more important in these individuals. These observations may explain the reduced efficacy of CA procedures that are limited to PVI in patients with longstanding persistent AF seen in most studies. In these patients, additional lesions are often needed to prevent recurrence of AF. These lesions are often placed anatomically in the left atrial posterior wall and roof, in the left atrial appendage, coronary sinus, or in the right atrium. Additional targets include sites of complex fractionated electrograms and rotors [43,44] (see "Mechanisms of atrial fibrillation", section on 'Mechanisms of atrial fibrillation: triggers and substrates'). Though the goal of additional lesion sets are to modify the AF substrate, these approaches may also result in proarrhythmia through the creation of new reentrant circuits. Data supporting the benefits and optimal approach for the treatment of persistent AF are inconclusive and are often individualized by patient and operator. Additional ablation targets/techniques outside the PVs include: Non-PV triggers (eg, coronary sinus, posterior left atrium, crista terminalis) Complex fractionated electrograms (CFAEs) Linear ablation (LA roof, mitral isthmus) Other thoracic veins (superior vena cava, coronary sinus) Posterior wall isolation Left atrial appendage isolation Ablation of cardiac autonomic nerves (ganglionic plexi) Focal impulse and rotor modulation (FIRM) phase mapping-guided ablation Stepwise approach (PVI, CFAE, linear, coronary sinus) https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 11/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate POSTPROCEDURAL ISSUES After the procedure, patients usually remain supine for a fixed period (usually two to four hours) following sheath removal to promote hemostasis at the venous puncture sites. Vascular closure devices allow for more rapid hemostasis and shorter time to ambulation. Most centers keep patients overnight following the procedure. Same-day discharge has become increasingly common given the shorter procedure times and use of venous closure techniques [45,46]. Post-discharge medications Oral anticoagulation is usually continued [47] for at least two months to ensure that the increased risk of embolization associated with the procedure has returned to a baseline risk, regardless of CHADS VA Sc score. This also allows for adequate time 2 2 to document an absence of recurrence of AF for those patients in whom practitioners and patients are contemplating discontinuing anticoagulation [48]. Importantly, there are no randomized data on the safety of discontinuing anticoagulation post-ablation for patients who have presumably maintained sinus rhythm. The risk of AF recurrence, the recognized proportional increase in the burden of asymptomatic AF, and the uncertainty surrounding the causal association between the arrhythmia itself and stroke all support the recommendation to risk stratify patients for oral anticoagulation use based on CHA DS -VASc no differently than if an 2 2 ablation had not been performed. (See "Catheter ablation to prevent recurrent atrial fibrillation: Anticoagulation", section on 'Postprocedural anticoagulation'.) Antiarrhythmic medications may or may not be continued after the procedure. Our preference is to stop them after the procedure. Patients in whom consideration should be given to continuing them include patients with long-standing persistent AF or patients with debilitating AF symptoms. Post-discharge follow-up At the time of discharge, patients are given instructions on activity and what potential complications to look for. They should refrain from heavy physical activity, including exercise and weight lifting, for the week post-procedure to allow for complete healing of the vascular access sites. Baths should also be avoided for one week to reduce infection risk. In patients without identified post-procedural complications such as vascular access site problems, we wait three months to reevaluate the patient [9] (see 'Complications' below). Patients with potential complications should be seen immediately. Patients who develop symptoms should contact either their primary care physician, general cardiologist, or electrophysiologist to discuss the need for early evaluation. Yearly follow-up with a physician thereafter is also recommended. These ongoing interactions with the medical profession allow the patient's clinical status to be evaluated, including an https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 12/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate assessment of the presence or absence of AF, as well as their stroke risk profile and anticoagulation needs. These interactions also provide an opportunity to focus on the treatment of associated diseases and lifestyle modifications [9]. Routine ECG should be performed at the time of follow-up visits, and more intense monitoring may be performed as dictated by patient symptoms and the clinical impact of AF detection [41]. Evaluation for recurrent atrial fibrillation The primary purpose of the first follow-up visit around the three-month mark is to determine the success of the procedure. Screening for post- procedure AF is discussed separately. (See "Atrial fibrillation: Catheter ablation", section on 'Follow-up'.) In general, we do not evaluate the patient for the presence of AF prior to three months, as early episodes do not necessarily predict the long-term success or failure of the procedure. They can often be managed with antiarrhythmic drugs or cardioversion. Repeat ablation during this time is rarely necessary. During this three-month healing phase, there is resolution of inflammation and consolidation of lesion formation. This time period is referred to in clinical research trials as the "post-procedure blanking period." Anticoagulants are continued throughout this period regardless of the patient's CHA DS -VASc score ( table 1). Antiarrhythmic drugs and/or electrical cardioversion 2 2 are used during this blanking period at the discretion of the treating physician and usually reserved for those with debilitating symptoms or recurrent persistent AF. Success rates The success rate of AF ablation is dependent on multiple factors including patient selection, technique, definition of success, and the intensity and duration of rhythm monitoring post-ablation. For research purposes, the primary endpoint of AF ablation trials is freedom from recurrent AF/ atrial tachycardia (AT) defined as the absence of any recurrent AF/AT >30 seconds without antiarrhythmic drugs. Using this strict definition, the one-year success rate for paroxysmal AF is approximately 70 to 80 percent and 60 to 70 percent for persistent AF at most experienced centers. However, a greater proportion of patients will derive an improvement in AF-related symptoms from ablation, and studies using implantable cardiac monitors or other devices that can record all episodes of AF have shown an AF burden reduction of over 98 percent [49]. (See "Maintenance of sinus rhythm in atrial fibrillation: Catheter ablation versus antiarrhythmic drug therapy", section on 'Patients with prior antiarrhythmic drug treatment'.) Complications Complications are discussed in detail separately. (See "Atrial fibrillation: Catheter ablation", section on 'Complications'.) https://www.uptodate.com/contents/catheter-ablation-for-the-treatment-of-atrial-fibrillation-technical-considerations-for-non-electrophysiologists/print 13/27 7/5/23, 9:12 AM Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists - UpToDate SOCIETY GUIDELINE LINKS Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Atrial fibrillation" and "Society guideline links: Arrhythmias in adults".) INFORMATION FOR PATIENTS UpToDate offers two types of patient education materials, The Basics and Beyond the Basics. th th The Basics patient education pieces are written in plain language, at the 5 to 6 grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more th th sophisticated, and more detailed. These articles are written at the 10 to 12 grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon. Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on patient info and the keyword(s) of interest.) Beyond the Basics topics (see "Patient education: Atrial fibrillation (Beyond the Basics)") SUMMARY AND RECOMMENDATIONS Pulmonary vein origin of atrial fibrillation (AF) The primary trigger for most episodes