Additional Ablation Strategies Research Articles

The contribution of pulmonary veins to the mechanism of persistent AF is dependent on their extent of electrical connection

Abstract Introduction Success rate of pulmonary vein isolation (PVI) is lower in patients with persistent AF (peAF) compared to paroxysmal AF. The indiscriminate use of adjunctive catheter ablation (CA) strategies beyond PVI involve potential risks and new areas of iatrogenic arrhythmogenesis. Thus, distinguishing patients with peAF who may be cured with PVI-only from those who need CA beyond PVI would allow a more efficient patient-tailored CA strategy. Purpose We aimed to evaluate whether the circumferential extent of PV electrical connection assessed during pre-ablation mapping predicts the success rate of a PVI-only CA strategy. Methods Consecutive patients with peAF undergoing first CA consisting of a PVI-only CA were included. The extent of PV electrical connection was assessed using a circular mapping catheter placed within the PVs prior to ablation. Based on their follow-up (FU), patients were considered: a) PVI-responders, in the absence of AF or atrial flutter recurrence ≥ 12 months off-anti-arrhythmic drugs, b) PVI-non responders, in case of AF recurrence despite absence of any PV reconnection at reintervention, or despite one reintervention consisting of stand-alone residual PV connection ablation, c) PVI response was considered as indeterminate for all other instances (eg. Sinus rhythm maintenance on-AAD, shorter FU, etc). Results 148 patients were included (mean age 64 ± 9.7 years, mean peAF duration 7.3 ± 7 months). After a mean FU of 18 months after last PVI, we identified 60 PVI-responders and 25 PVI- non responders. In the remaining 63 patients, PVI response was indeterminate. In PVI-responders, the median percentage of the PV circumference displaying PVs potentials was significantly higher compared to PVI-non responders (68% vs. 60%, respectively; p=0.035). Conclusions The circumferential extent of PVs connection is correlated to the success rate of a stand-alone PVI CA strategy in patients with peAF. It may be a marker of the contribution of PVs to AF. Patients with poorly connected PVs during index CA ablation may warrant additional ablation strategies beyond PVI.

Hybrid ablation for persistent atrial fibrillation: a narrative review.

Treatment for atrial fibrillation (AF) has evolved significantly, with pulmonary vein isolation (PVI) becoming an established treatment. However, the outcomes following catheter ablation for persistent AF remain unsatisfactory. Hybrid catheter-surgical ablation has emerged as a therapeutic approach for persistent AF, combining the strengths of both interventions. The purpose of this narrative review is to comprehensively examine the current state of knowledge regarding hybrid ablation for AF. A thorough PubMed search using the terms "hybrid ablation", "atrial fibrillation", "catheter ablation", and "guideline on cardiology" within the timeframe of 1980 to 2024 resulted in 138,969 articles. Consensus on the selected articles was reached through a series of structured meetings and discussions. PVI has demonstrated higher sinus rhythm maintenance rates, especially for paroxysmal AF. However, the efficacy is not as high for persistent AF. Additional ablation strategies, such as linear ablation, complex fractionated atrial electrogram ablation, low voltage zone ablation as well as posterior wall isolation, lack consistent evidence of effectiveness. Hybrid ablation, involving collaboration between cardiac surgeons and electrophysiologists, presents a promising alternative for hard-to-treat AF. Recent studies report favorable outcomes of hybrid ablation, with atrial arrhythmia-free rates ranging from 53.5% to 76%, surpassing those of catheter ablation alone, which might result from better lesion durability or intervention for non-PV foci and left atrial appendage excision or closure during hybrid ablation. The rate of complications associated with hybrid ablation is higher than catheter ablation alone. While favorable outcomes of hybrid ablation for persistent AF have been reported, it is not recommended for all AF patients due to its invasiveness compared to catheter ablation. Additionally, some patients with persistent AF maintain sinus rhythm with catheter ablation alone. More clinical data are needed to determine which patients are suitable candidates for hybrid ablation.

Association with the nonparoxysmal atrial fibrillation duration and outcome of ExTRa Mapping-guided rotor ablation.

Additional ablation strategies after pulmonary vein isolation (PVI) for patients with nonparoxysmal atrial fibrillation (non-PAF) lasting ≥2 years have not been fully effective. This is presumably because of insufficient identification of non-PAF maintenance mechanisms. In this study, we employed a novel online and real-time phase mapping system, ExTRa Mapping, to identify and modulate rotors as one of the non-PAF maintenance mechanisms in patients with non-PAF sustained after PVI. We investigated the relationship between outcomes of ExTRa Mapping-guided rotor ablation (ExTRa-ABL) and non-PAF duration prior to this procedure. This study consisted of 73 non-PAF patients (63 ± 8 years, non-PAF duration 31 ± 37 months) who underwent the first ExTRa-ABL in patients with non-PAF sustained after completion of PVI. Freedom from non-PAF/atrial tachycardia (AT) recurrence at 12 months after ExTRa-ABL was achieved in 50 (69%) of patients. The non-PAF duration prior to ExTRa-ABL was significantly longer in patients with non-PAF/AT recurrence after ExTRa-ABL compared with those without (56 ± 50 vs. 19 ± 22 months, p = .001). In patients with non-PAF duration of ≤60 months prior to ExTRa-ABL, compared with >60 months, non-PAF/AT-free rate was significantly higher (68.9% vs. 23.1%, p < .001), during the follow-up of 36 ± 18 months. A non-PAF duration of ≤60 months prior to ExTRa-ABL was associated with a better outcome. The effect of ExTRa-ABL was considered to be limited in patients with >60 months of non-PAF duration.

AB-452642-1 TEMPORAL TREND IN PROCEDURE-RELATED COMPLICATIONS OF CATHETER ABLATION FOR ATRIAL FIBRILLATION: A SYSTEMATIC REVIEW AND POOLED ANALYSIS OF RANDOMIZED CONTROL TRIALS.

Catheter ablation of atrial fibrillation (AF) is one of the most commonly performed procedures in electrophysiology. However, it is associated with potentially significant complications. Reported procedure-related complication rates are highly variable, depending in part on study design. Objectives of this systematic review and pooled analysis were to determine the rate of procedure-related complications associated with catheter ablation of AF using data from randomized control trials (RCTs), and to assess temporal trends. MEDLINE and EMBASE databases were searched from January 2013 to September 2022 for RCTs that included patients undergoing a first catheter ablation procedure for the treatment of AF using either radiofrequency or cryoballoon ablation (PROSPERO CRD42022370273). The study adhered to Cochrane Collaboration guidelines. The quality of included trials was assessed using the Cochrane Collaboration’s tool for assessing risk of bias in RCTs. Results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses report. A total of 1,468 references were retrieved and evaluated, of which 89 studies met inclusion criteria. A total of 15,701 patients who underwent a first catheter ablation procedure for AF were included in the current analysis. Procedure-related and severe complication rates were 3.5% (95%CI: 2.9-4.1) and 2.1% (95%CI: 1.7-2.5), respectively. Vascular complications were the most frequent type of complication (1.21%). The most frequently reported complications were then pericardial effusions and tamponades (0.51%), strokes/transient ischemic attacks (0.48%) and reversible phrenic nerve palsy (0.40%). The procedure-related complication rate during the most recent 5-year period of publication [2018-2022] was significantly lower than during the earlier 5-year period [2013-2017] (2.9% vs 4.1%, p=0.043). The pooled mortality rate was stable over the two time periods (0.06% vs 0.05%, p=0.562). By meta-regression analyses, there was no significant difference in complication rate according to pattern of AF (paroxysmal or non-paroxysmal), ablation modality (radiofrequency or cryoballoon), or additional ablation strategies beyond pulmonary vein isolation. Procedure-related complications and mortality rates associated with catheter ablation of AF are low and have declined in the past decade.

Abstract 11159: Assessment of Atrial Cardiomyopathy by High-Density Mapping Can Guide Additional Procedures in AF Ablation

Background: The efficacy of catheter ablation (CA) for atrial fibrillation (AF) has been lower in persistent AF (PeAF). Additional ablation strategies beyond pulmonary vein isolation (PVI) are not routinely recommended in PeAF because their efficacy is not established yet. The clinical AF patterns could not expect the degree of atrial abnormal voltage area (AVA). The inability to discriminate significant atrial cardiomyopathy may lead to diverse ablation outcomes beyond PVI in PeAF. Objectives: The objective of this study was to find out how much proportion of AVA can predict higher AF recurrence after PVI. Methods: We enrolled the consecutive 49 patients who underwent CA of AF. LA was mapped with Pentaray® catheter (2-6-2 spacing) during mid-CS pacing (600msec) using the CONFIDENCE Module. The peak-to-peak bipolar voltage was obtained using only 2mm spacing electrodes. The AVA was defined when the bipolar voltage was &lt; 1.5mV, which is known to be normal in LA. After excluding PVs, appendage, and mitral valve region, the proportion of AVA was calculated by the Carto 3 mapping system. The ablation strategy was PVI only regardless of the AF pattern &amp; degree of AVA. Results: The mean age was 58.1 ± 7.7 years, and 73.5% were male. The average mapping points were 3557.5 ± 760.9. The average proportion of AVA was 31.4 ± 15.3%. The paroxysmal AF (PAF) patients were 71.4%, and the mean AVA between PAF and PeAF was significantly different (28.7 ± 15.5 vs. 38.2 ± 12.7, p=0.049). The mean follow-up duration was 265.8 ± 150.4 days. Atrial tachyarrhythmia recurred in 35.7%. In receiver-operating curve analysis, the proportion of AVA of 33.4% predicts AF recurrence regardless of AF type with a sensitivity of 75% and specificity of 78.8% (AUC 0.864, P&lt;0.001). Conclusion: More than one-third of AVA assessed by high-density mapping could be used as a predictor of the recurrence of AF after CA, which may guide the consideration of additional ablation. However, a randomized controlled trial is warranted.

Abstract 11177: Pulmonary Vein Reconnections Predict Good Clinical Outcomes After a Second Catheter Ablation of Persistent Atrial Fibrillation: Insight From the EARNEST-PVI Trial

Introduction: The effect of an extensive ablation strategy in addition to pulmonary vein (PV) isolation is still controversial in persistent atrial fibrillation (AF) ablation. Electrical PV reconnection is an important confounder affecting the trial results. Objectives: To evaluate the PV reconnection rate and association between the reconnection and AF recurrence after a re-do AF ablation in the EARNEST-PVI trial (NCT03514693). Methods: The analysis was performed using the extended data of the EARNEST-PVI trial (N=512), a randomized controlled trial to evaluate ablation strategies for persistent AF, which was conducted in the Osaka region of Japan. During a median follow-up of 47 months, a total of 126 (25%) patients underwent a re-do AF ablation. Among them, 120 (median age, 68 years; 36% female; 31% long-standing persistent AF, 95% contact force-sensing catheter use) whose follow-up data were available after the 2 nd AF ablation were enrolled in this study. Results: PV reconnections were observed in 75 (63%) patients. Although there was no difference in age, gender, long-standing persistent AF, and CA strategy during the index procedure, AF recurrence within 1 year was more frequent in patients with PV reconnections (81.3% vs. 64.4%, p = 0.039). During a median follow-up of 31 months after the re-do AF ablation, patients with PV reconnections had a lower clinical recurrence rate than those without (38.7 vs. 44.4%, log-rank p = 0.047). However, additional linear ablation did not affect the recurrence rate. Even after adjustment for age, gender, long-standing persistent AF, and presence of non-PV triggers, Cox regression analysis revealed that a number of reconnected PVs of ≥2 was independently associated with a lower recurrence of AF after the 2 nd AF ablation (hazard ratio, 0.36; 95% confidence interval, 0.19-0.67; p = 0.001). Conclusions: Among patients who underwent a redo-AF ablation in the EARNEST-PVI trial, about two-thirds exhibited PV reconnections. Patients with ≥2 PV reconnections had better clinical outcomes than those with ≤1 PV reconnections. A durable PV isolation is an important pre-requisite before exploring any additional ablation strategies for persistent AF.

Catheter ablation for atrial fibrillation in adult congenital heart disease: an international registry study

Abstract Background Life expectancies for patients with congenital heart disease (CHD) have dramatically increased in recent years, accompanied by a rise in atrial fibrillation (AF) prevalence. Data on AF ablation strategy and outcomes are limited in CHD. Purpose We aimed to investigate the characteristics of CHD patients presenting for AF ablation and their outcomes. Methods A multicenter, retrospective analysis was performed of CHD patients undergoing AF ablation between 2004 and 2020 at 13 participating centers. The severity of CHD was classified using the 2014 PACES/HRS guidelines. Clinical data were collected including ablation strategy and follow up. One-year procedural success was defined as freedom from AF in the absence of antiarrhythmic drugs (AADs, complete) or including previously failed AADs (partial). Results Of 240 patients, 127 (53.4%) had persistent AF, 62.5% were male, and mean age was 55.2±0.9 years. CHD complexity categories included 147 (61.3%) simple, 69 (28.8%) intermediate and 25 (10.4%) severe. The most common CHD type was atrial septal defect (n=78). More complex CHD conditions included transposition of the great arteries (n=14), anomalous pulmonary veins (n=13), tetralogy of Fallot (n=8), cor triatriatum (n=7), single ventricle physiology (n=2), among others. The majority (71.3%) of patients had AF despite at least one AAD. 46 patients (22.1%) had a reduced systemic ventricular ejection fraction &amp;lt;50%, and the mean left atrial diameter was 44.1±0.7 mm. PV isolation (PVI) was performed in 227 patients (94.6%); additional ablation strategies included left atrial linear ablations (25.4%), CFAE (19.2%), and cavotricuspid isthmus ablation (40.8). One-year complete and partial success rates were 45.0% and 20.5%, respectively, with no significant difference in the rate of complete success between complexity groups. Overall, 38 patients (15.8%) required more than one ablation procedure. There were 3 (1.3%) major and 13 (5.4%) minor procedural complications. Conclusion AF ablation in this complex population was safe and resulted in AF control in the majority of patients. Future work should address the most appropriate ablation targets in the challenging population. Funding Acknowledgement Type of funding sources: None.

Pulmonary vein isolation alone vs. more extensive ablation with defragmentation and linear ablation of persistent atrial fibrillation: the EARNEST-PVI trial.

Previous studies could not demonstrate any benefit of more intensive ablation in addition to pulmonary vein isolation (PVI) including complex fractionated atrial electrogram (CFAE) and linear ablation for recurrence in the initial catheter ablation of persistent atrial fibrillation (AF). This study aimed to establish the non-inferiority of PVI alone to PVI plus these additional ablation strategies. Patients with persistent AF who underwent an initial catheter ablation (n = 512, long-standing persistent AF; 128 cases) were randomly assigned in a 1:1 ratio to either PVI alone (PVI-alone group) or PVI plus CFAE and/or linear ablation (PVI-plus group). After excluding 15 cases who did not receive procedures, we analysed 249 and 248 patients, respectively. The primary endpoint was recurrence of AF, atrial flutter, and/or atrial tachycardia, and the non-inferior margin was set at a hazard ratio of 1.43. In the PVI-plus group, 85.1% of patients had linear ablation and 15.3% CFAE ablation. After 12 months, freedom from the primary endpoint occurred in 71.3% of patients in the PVI-alone group and in 78.3% in the PVI-plus group [hazard ratio = 1.56 (95% confidence interval: 1.10-2.24), non-inferior P = 0.3062]. The procedure-related complication rates were 2.0% in the PVI-alone group and 3.6% in the PVI-plus group (P = 0.199). This randomized trial did not establish the non-inferiority of PVI alone to PVI plus linear ablation or CFAE ablation in patients with persistent AF, but implied that the PVI plus strategy was promising to improve the clinical efficacy (NCT03514693).

Catheter Ablation of Atrial Fibrillation: State of the Art and Future Perspectives.

Purpose of ReviewAtrial fibrillation (AF), the most common sustained arrhythmia, is associated with high rates of morbidity and mortality. Maintenance of stable sinus rhythm (SR) is the intended treatment target in symptomatic patients, and catheter ablation aimed at isolating the pulmonary veins provides the most effective treatment option, supported by encouraging clinical outcome data. A variety of energy sources and devices have been developed and evaluated. In this review, we summarize the current state of the art of catheter ablation of AF and describe future perspectives.Recent FindingsCatheter ablation is a well-established treatment option for patients with symptomatic AF and is more successful at maintaining SR than antiarrhythmic drugs. Antral pulmonary vein isolation (PVI) as a stand-alone ablation strategy results in beneficial clinical outcomes and is therefore recommended as first-line strategy for both paroxysmal and persistent AF. While radiofrequency-based PVI in conjunction with a three-dimensional mapping system was for many years considered to be the “gold standard”, the cryoballoon has emerged as the most commonly used alternative AF ablation tool, especially in patients with paroxysmal AF. Patients with persistent or long-standing persistent AF and with arrhythmia recurrence after previous PVI may benefit from additional ablation strategies, such as substrate modification of various forms or left atrial appendage isolation. New technologies and techniques, such as identification of the AF sources and magnetic resonance imaging-guided substrate modification, are on the way to further improve the success rates of catheter ablation for selected patients and might help to further reduce arrhythmia recurrence.ConclusionsPulmonary vein isolation is the treatment of choice for symptomatic patients with paroxysmal and persistent drug-refractory AF. The reconnection of previously isolated pulmonary veins remains the major cause of AF recurrence. Novel ablation tools, such as balloon technologies or alternative energy sources, might help to overcome this limitation. Patients with non-paroxysmal AF and with AF recurrence might benefit from alternative ablation strategies. However, further studies are warranted to further improve our knowledge of the underlying mechanisms of AF and to obtain long-term clinical outcomes on new ablation techniques.

P983Long-standing persistent atrial fibrillation: what can we achieve with ablation?

Abstract Introduction Atrial fibrillation (AF) ablation presents suboptimal results in patients (pts) with persistent long-lasting forms (LSPAF, AF ≥12 months). Recently, the STAR AF-II trial has shown that in these pts complex additional strategies do not improve success compared to only performing pulmonary vein isolation (PVI). Objectives To evaluate the success of AF ablation, particularly in long-standing persistent AF Methods Single-center prospective study of pts with AF submitted to ablation. The strategy, regardless of the type of AF, was based on PVI, complemented by cavo-tricuspid isthmus line (CTI) in pts with history of flutter. Additional ablation strategies were selectively considered in pts with stable atypical flutter conversion, persistent triggers or no electrograms in the VPs. Pts were monitored with Holter/7-day event loop recorder (3, 6, 12 months and annually up to 5 years). Success was assessed from the 90th day after ablation, with the absence of recurrences of any sustained atrial arrhythmias (&gt;30 sec). Cox regression and Kaplan-Meier survival were used to compare the success of ablation as a function of the clinical type of AF in our population and with pts included in STAR-II AF trial. Results 620 patients were submitted to AF ablation, 67% male, 58±12 years, including 78 pts (13%) with LSPAF - pts with paroxysmal and persistent short duration AF represented 61% and 26% of the population. In LSPAF, VPI was performed with irrigated catheter (N=33), PVAC (N=44) or nMARQ (N=1), complemented by CTI ablation in 15, linear left atrial lesions in 3, ablation of areas of low voltage in 3 and elimination of fractionated electrograms in 1 patient. With a median follow-up of 426 days (94–989), the 3-year success rate after a single procedure was 53% in LSPAF, lower than that observed in patients with paroxysmal AF (69%) or short-duration persistent AF (61%) - LogRank P=0.002. The risk of arrhythmias was double in LSPAF vs paroxysmal AF (HR: 2.0; P=0.001). However, after an average of 1.2 procedures/patient, the success rate in LSPAF was 80% at 3 years, comparable to that observed for other types of AF (Log Rank 2.5, p=0.29). Effectively, the long-term success rate of our LSPAF pts treated with PVI and very selective additional strategies was higher than that observed in the STAR-II AF pts treated with PVI and indiscriminate complex ablations (80% vs. 69%, t-test p&lt;0.001, with similar mean follow-up). Conclusions AF ablation is more effective if it is performed earlier in the natural history of the disease. However, even in LSPAF, high success rates are achieved through PVI-based ablation strategies, although more procedures are required.

Catheter ablation of atrial fibrillation: current status, techniques, outcomes and challenges

Atrial fibrillation (AF) is the most common human arrhythmia. Interventional treatment with catheter ablation is an established technique that is increasingly applied and has become one of the main treatment modalities in patients with AF. Ablation results in significant improvement of symptoms and the quality of life. There is as yet no clear evidence of any impact of the procedure on hard clinical endpoints, except in patients with heart failure, who seem to benefit significantly from ablation. The cornerstone of the procedure is the achievement of pulmonary vein isolation. Radiofrequency energy is the main applied energy source, but cryoballoon ablation has emerged as a safe and effective alternative to radiofrequency ablation. Additional ablation strategies and novel technical features have been proposed but without unequivocal proof of clinical benefit. The most promising of these seems to be substrate mapping of the left atrium with substrate modification in areas with low voltage as an adjunct to pulmonary vein isolation. Complication rates remain considerable despite accumulated experience and can be partly reduced by application of preventive measures.

Durability of wide-area left atrial appendage isolation: Results from extensive catheter ablation for treatment of persistent atrial fibrillation

Extensive ablation strategies are currently performed in addition to pulmonary vein isolation (PVI) to improve the clinical outcome of patients with drug-refractory persistent atrial fibrillation (AF). Ablation of complex fractionated atrial electrograms (CFAEs), linear lesions, and/or isolation of the left atrial appendage (LAA) are thought to improve arrhythmia-free survival. The purpose of this study was to assess the durability of wide-area left atrial appendage isolation (LAAI) achieved by PVI, an anterior line, and a mitral isthmus line. Seventy-one patients with intentional or incidental LAAI during repeat catheter ablation for treatment of persistent AF were included. The initial ablation strategy was PVI. Additional ablation strategies were performed only if PVI failed to maintain stable sinus rhythm. Durability of LAAI was assessed during a subsequent ablation procedure for arrhythmia recurrences (n = 23) or a subsequent percutaneous LAA closure (n = 48). LAAI was performed after a mean of 3 ± 1 procedures. Ablation strategies included circumferential PVI in 71 patients (100%), mitral isthmus line in 64 (90%), anterior line in 60 (85%), CFAE in 27 (38%), and roof line in 13 (18%). LAAI occurred after ablation and bidirectional block of LA linear lesions in 63 patients (89%) and during extensive CFAE ablation in 8 patients (11%). After a median of 105 [61;426] days, the LAA remained electrically isolated in 52 of 71 patients (73%). Wide-area LAAI after extensive catheter ablation for persistent AF is durable in the majority of patients. The potential clinical benefit of LAAI for maintaining stable sinus rhythm requires further investigation.

Predictors of Recurrence After Radiofrequency Ablation of Persistent Atrial Fibrillation.

Radiofrequency catheter ablation that targets the pulmonary veins is well established as a mainstay for drug-refractory, paroxysmal atrial fibrillation (AF). However, in patients with persistent AF, the ideal approach remains elusive. Further, despite the various additional ablation strategies that have been investigated in patients with persistent AF, the rate of recurrent atrial tachyarrhythmias after ablation remains relatively high. In this review, the predictors of recurrent atrial tachyarrhythmias after catheter ablation of persistent AF will be discussed.

Linear ablation for atrial fibrillation guided by acoustic imaging: “How does it sound?”

Despite advances in techniques on catheter ablation of atrial fibrillation (AF), a substantial proportion of patients after ablation had recurrences of AF, and even after multiple repeated procedures. Pulmonary vein isolation remains the cornerstone of most AF ablation procedures, and additional ablation strategies such as creation of lines of conduction block in the left atrium (LA) and right atrium (RA) and ablation targeting onpulmonary vein triggers, the autonomic ganglia, or complex fractionated electrograms have been employed in either the initial or the repeat procedure with variable success. Catheter-based linear atrial ablation attempts to replicate the surgical Maze procedure, in which up to a 90% long-term success rate of maintaining sinus rhythm has been reported. The comparatively lower success rate of catheter vs surgically delivered linear ablation could be explained by multiple factors such as inadequate line continuity and transmurality, difference in line design, and additional effect of surgical procedures on autonomic ganglia. Among these factors, uncertainty in creating a complete line of block is thought to be the main Achilles tendon of catheter-based approach, not only because it is unable to eliminate AF but also because it is potentially proarrhythmogenic. In this issue of HeartRhythm, Eyerly et al report their experience of using intracardiac acoustic radiation force impulse imaging (ARFI) in animals to guide the creation of a complete line of block. This technology is based on the principle that focused and short duration intracardiac ultrasound will create an acoustic force on myocardial tissue. These pulses induce local tissue displacements that are influenced by tissue characteristics. Thus, protein denaturation following catheter blation will result in a “stiffer” myocardium compared with he surrounding untreated myocardium and thus provide an ndicator of the adequacy of catheter ablation, almost like an ndirect “palpation” of the tissue characteristics. The authors have demonstrated previously in an in vitro porcine myocardium model that this technology is capable of “visualizing” radiofrequency ablation (RFA)-induced lesions of dimension within 1 mm (axial) to 2 mm (lateral).

Catheter Ablation of Long‐Standing Persistent Atrial Fibrillation: A Lesson from Circumferential Pulmonary Vein Isolation

Circumferential pulmonary vein isolation (CPVI) is associated with a high success rate in patients with paroxysmal and persistent atrial fibrillation (AF). However, in patients with long-standing persistent AF, the ideal ablation strategy still remains a matter of debate. Two-hundred and five patients underwent catheter ablation for long-standing persistent AF defined as continuous AF of more than 1-year duration. In a first step, all patients underwent CPVI. If direct-current cardioversion failed following CPVI, ablation of complex fractionated atrial electrograms (CFAEs) was performed. The goal was conversion into sinus rhythm (SR) or, alternatively, atrial tachycardia (AT) with subsequent ablation. A total of 340 procedures were performed. CPVI alone was performed during 165 procedures in 124 of 205 (60.5%) patients. In the remaining 81 patients, additional CFAE ablation was performed in 45, left linear lesions for recurrent ATs in 44 and SVC isolation in 15 patients, respectively, resulting in inadvertent left atrial appendage isolation in 9 (4.4%) patients. After the initial ablation procedure, 67 of 199 patients remained in SR during a mean follow-up of 19 ± 11 months. Six patients were lost to follow-up. After a mean of 1.7 ± 0.8 procedures, 135 of 199 patients (67.8%) remained in SR. Eighty-six patients (43.2%) remained in SR following CPVI performed as the sole ablative strategy. CPVI alone is sufficient to restore SR in 43.2% of patients with long-standing persistent AF. Multiple procedures and additional ablation strategies with a significant risk of inadvertent left atrial appendage isolation are often required to maintain stable SR.

Novel non-pharmacological approaches for antiarrhythmic therapy of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. Its prevalence is increasing in our ageing population, and it has a soaring impact on health systems. It can cause thrombo-embolism, heart failure, and hospitalizations, and is associated with a two-fold increase in all-cause mortality. There have been great advances in understanding the mechanism of AF that are currently being translated into new therapeutic concepts. Experimental studies demonstrated that AF-induced electrical and structural remodelling of the fibrillating atria perpetuate AF ('AF begets AF'). Furthermore, there is growing understanding that the atria are an endocrine organ expressing angiotensin and thrombogenic substances. Clinical, electrophysiological studies have identified automatic triggers, often in the pulmonary veins, that initiate paroxysmal AF. Electrical isolation of the pulmonary veins by circular ablation abolishes these triggers. Whereas isolation of the pulmonary veins often maintains sinus rhythm in patients with paroxysmal AF, additional ablation strategies are used in persistent and permanent AF to modify the more complex electrical and structural atrial changes. The 'role model' for extensive ablation in the left atrium is the surgical MAZE procedure that abolishes long-standing AF by cutting and sewing the atria into complex pieces. New surgical approaches of AF therapy use radiofrequency or other sources for an easy ablation during open-heart surgery. A lot of effort has also been put in the development of device therapy for the treatment of AF, with mixed effects on maintenance of sinus rhythm, but unexpected insights into the development of asymptomatic AF recurrences. This review aims to provide an overview of these non-pharmacological treatment options of AF in the context of potential pathophysiological processes.