Effect of MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation on Atrial Arrhythmia Recurrence in Patients With Persistent Atrial Fibrillation: The DECAAF II Randomized Clinical Trial

Small extracellular vesicles associated miRNA in myocardial fibrosis

Myocardial fibrosis involves the loss of cardiomyocytes, myocardial fibroblast proliferation, and a reduction in angiogenesis, ultimately leading to heart failure, Given its significant implications, it is crucial to explore novel therapies for myocardial fibrosis. Recently one emerging avenue has been the use of small extracellular vesicles (sEV)-carried miRNA. In this review, we summarize the regulatory role of sEV-carried miRNA in myocardial fibrosis. We explored not only the potential diagnostic value of circulating miRNA as biomarkers for heart disease but also the therapeutic implications of sEV-carried miRNA derived from various cellular sources and applications of modified sEV. This exploration is paramount for researchers striving to develop innovative, cell-free therapies as potential drug candidates for the management of myocardial fibrosis.

[Initial ablation of atrial fibrillation-Is pulmonary vein isolation sufficient? : Pro and contra]

Pulmonary vein isolation (PVI) is currently the gold standard for the ablation of atrial fibrillation (AF). Although this procedure shows good success rates, the recurrence rates after PVI alone are significantly higher in advanced AF and in the presence of comorbidities. Therefore, it is important to consider additional arrhythmogenic mechanisms outside the pulmonary veins, depending on the individual case, in order to improve the patients' outcome.

Catheter ablation for atrial fibrillation: indications and future perspective

Recent advances in techniques, technologies and proven superiority over anti-arrhythmic drugs have made catheter ablation the cornerstone of management for atrial fibrillation (AF), which has shown a steady increase in prevalence in the ageing population worldwide. The aim of therapeutic interventions is to achieve stable sinus rhythm that would improve the quality of life and reduce the risk of AF-associated complications. Pulmonary veins (PVs) were first described as the source of initiation of ectopic triggers driving AF, which led to the establishment of PV isolation (PVI) as the most widely practiced procedure to treat AF. Antral PVI is still recognized as the stand-alone ablation strategy for newly diagnosed paroxysmal AF (PAF). However, in non-PAF patients, PVI seems to be inadequate and several adjunctive strategies, including ablation of left atrial posterior wall and non-PV triggers, AF mapping and ablation of rotors and drivers, ethanol infusion of vein of Marshall and renal denervation, etc. have been reported with mixed results. Recent trials have also documented the benefits of early rhythm control in preventing cardiovascular events in addition to slowing the progression of PAF to more persistent forms. Similarly, very late relapse of the arrhythmia after successful PVI has drawn attention to the critical role of non-PV triggers and highlighted their relevance as potential ablation targets during repeat procedures. Ablation technology is also under constant evolution with the introduction of non-thermal energy sources and new tools to create durable lesions. This review summarizes the indications, advancements, and future perspective of AF ablation.

Atrial Fibrillation and Underlying Structural and Electrophysiological Heterogeneity

As atrial fibrillation (AF) progresses from initial paroxysmal episodes to the persistent phase, maintaining sinus rhythm for an extended period through pharmacotherapy and catheter ablation becomes difficult. A major cause of the deteriorated treatment outcome is the atrial structural and electrophysiological heterogeneity, which AF itself can exacerbate. This heterogeneity exists or manifests in various dimensions, including anatomically segmental structural features, the distribution of histological fibrosis and the autonomic nervous system, sarcolemmal ion channels, and electrophysiological properties. All these types of heterogeneity are closely related to the development of AF. Recognizing the heterogeneity provides a valuable approach to comprehending the underlying mechanisms in the complex excitatory patterns of AF and the determining factors that govern the seemingly chaotic propagation. Furthermore, substrate modification based on heterogeneity is a potential therapeutic strategy. This review aims to consolidate the current knowledge on structural and electrophysiological atrial heterogeneity and its relation to the pathogenesis of AF, drawing insights from clinical studies, animal and cell experiments, molecular basis, and computer-based approaches, to advance our understanding of the pathophysiology and management of AF.

Beyond pulmonary vein isolation: approaches to treat patients with persistent atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most common arrhythmia. Catheter ablation is a successful rhythm control strategy in paroxysmal AF, but it has demonstrated dramatically lower AF-free survival rates in patients with persistent AF. In recent years, myriad novel rhythm control strategies have been developed, each with the promise of improved persistent AF ablation success.

AREAS COVERED

This review discusses multiple novel techniques and approaches to persistent AF. Authors identified relevant papers by searching PubMed and Google Scholar databases and considered all papers identified, regardless of publication date. It begins by discussing recent advances in electrogram analysis that yielded improved AF-free survival following persistent AF catheter ablation. Next, it discusses several trials revealing the shortcomings of MRI in guiding persistent AF ablation. Finally, it discusses one nascent technique (Vein of Marshall ablation) and technology (AI-assisted electrogram analysis) who have shown promise in improving persistent AF ablation.

EXPERT OPINION

In the authors' expert opinions, upcoming persistent AF ablations will utilize a stepwise approach of (1) ensuring PV isolation, (2) Vein of Marshall ablation and (3) AI-assisted ablation to optimize future persistent AF ablation outcomes. This approach systematically addresses arrhythmogenic sources beyond the pulmonary veins, the historical treatment target.

Coronary sinus signal amplitude: A predictor of the atrial substrate and low voltage areas

BACKGROUND

Low voltage areas (LVA) are pivotal in atrial fibrillation (AF) pathogenesis, influencing local left atrial LA excitation and perpetuating AF occurrences. While pulmonary vein isolation (PVI) with cryo-balloon (CB) ablation is effective for AF, it doesn't provide insights into the LA substrate or detect LVA, which affects ablation success rates. This study examines whether LA voltage and LVAs can be anticipated by analyzing the voltage signal amplitude at the coronary sinus (CS) catheter, which is standard in CB and radiofrequency ablation procedures.

METHODS

A retrospective analysis of 284 patients with recurrent AF undergoing RF catheter ablation was conducted at a high-volume EP center in Germany. The correlation between LA voltage and LVA with the CS signal was explored.

RESULTS

The signal amplitude in the CS significantly correlated with voltage in LA walls, particularly in the proximal CS (correlation coefficient ρ = 0.81, p < 0.001). A CS signal cut-off of 1.155 mV effectively predicted severe atrial LVAs (>40%) with a sensitivity of 90.7% and a specificity of 100%. While a threshold of 1.945 mV identified patients with no significant atrial LVAs (<5%) with a sensitivity of 88% and a specificity of 50% (AUC: 0.81, 95% CI: 0.71-0.89, p < 0.001).

CONCLUSION

The CS signal amplitude is associated with the LA voltage. Due to its potential as a diagnostic tool for atrial LVAs, the signal amplitude in the CS could provide valuable information about the LA substrate, especially when 3D mapping is not feasible.

Lesion delivery and scar formation in catheter ablation for atrial fibrillation: The DECAAF II trial

BACKGROUND

The Efficacy of Delayed Enhancement MRI-Guided Fibrosis Ablation vs Conventional Catheter Ablation of Atrial Fibrillation randomized trial showed no difference in atrial fibrillation (AF) recurrence with additional delayed enhancement magnetic resonance imaging (DE-MRI) fibrosis-targeted ablation to pulmonary vein isolation (PVI) in persistent AF.

OBJECTIVE

We evaluated the effect of lesion delivery on ablation-induced scarring and AF recurrence.

METHODS

Lesions delivered, targeting fibrotic and nonfibrotic areas identified from preablation DE-MRI, were studied in relation to ablation-induced scarring on 3-month DE-MRI, including their association with arrhythmia recurrence.

RESULTS

A total of 593 patients treated with radiofrequency were analyzed: 293 underwent PVI and 300 underwent additional fibrosis-guided ablation. Lesion analysis showed that 80.9% in the MRI fibrosis-guided group vs 16.5% in the PVI group (P < .001) had ≥40% of baseline fibrosis targeted. MRI assessment of ablation-induced scar showed that 44.8% of fibrosis-guided ablation and 15.5% of PVI had ≥40% of their fibrosis covered by scar (P < .001), demonstrating significant attenuation from lesions delivered to scar formed. In the overall population, fibrosis coverage with scar was not associated with recurrence (hazard ratio [HR] 0.90; 95% confidence interval [CI] 0.80-1.01; P = .08 per 20% increase). In patients with baseline fibrosis < 20%, fibrosis coverage with scar was associated with lower recurrence than PVI (HR 0.85; 95% CI 0.73-0.97; P = .03), whereas the association was not significant when baseline fibrosis ≥ 20% (HR 0.97; 95% CI 0.80-1.17; P = .77). Significant center variation was observed in fibrosis targeting and coverage with scarring.

CONCLUSION

Radiofrequency ablation lesions do not uniformly result in scar formation. A post hoc analysis suggests reduced arrhythmia recurrence when ablation-induced scarring covers fibrotic regions in patients with low baseline fibrosis.

Research Priorities for Atrial Fibrillation in Australia: A Statement From the Australian Cardiovascular Alliance Clinical Arrhythmia Theme

Atrial fibrillation (AF) is highly prevalent in the Australian community, ranking amongst the highest globally. The consequences of AF are significant. Stroke, dementia and heart failure risk are increased substantially, hospitalisations are amongst the highest for all cardiovascular causes, and Australians living with AF suffer from substantial symptoms that impact quality of life. Australian research has made a significant impact at the global level in advancing the care of patients living with AF. However, new strategies are required to reduce the growing incidence of AF and its associated healthcare demand. The Australian Cardiovascular Alliance (ACvA) has led the development of an arrhythmia clinical theme with the objective of tackling major research priorities to achieve a reduction in AF burden across Australia. In this summary, we highlight these research priorities with particular focus on the strengths of Australian research and the strategies needed to move forward in reducing incident AF and improving outcomes for those who live with this chronic condition.

Utility of CT and MRI in Cardiac Electrophysiology

Cardiac electrophysiology involves the diagnosis and management of arrhythmias. CT and MRI play an increasingly important role in cardiac electrophysiology, primarily in preprocedural planning of ablation procedures but also in procedural guidance and postprocedural follow-up. The most common applications include ablation for atrial fibrillation (AF), ablation for ventricular tachycardia (VT), and for planning cardiac resynchronization therapy (CRT). For AF ablation, preprocedural evaluation includes anatomic evaluation and planning using CT or MRI as well as evaluation for left atrial fibrosis using MRI, a marker of poor outcomes following ablation. Procedural guidance during AF ablation is achieved by fusing anatomic data from CT or MRI with electroanatomic mapping to guide the procedure. Postprocedural imaging with CT following AF ablation is commonly used to evaluate for complications such as pulmonary vein stenosis and atrioesophageal fistula. For VT ablation, both MRI and CT are used to identify scar, representing the arrhythmogenic substrate targeted for ablation, and to plan the optimal approach for ablation. CT or MR images may be fused with electroanatomic maps for intraprocedural guidance during VT ablation and may also be used to assess for complications following ablation. Finally, functional information from MRI may be used to identify patients who may benefit from CRT, and cardiac vein mapping with CT or MRI may assist in planning access. ©RSNA, 2024 Supplemental material is available for this article.

Subjective identification and ablation of drivers improves rhythm control in patients with persistent atrial fibrillation. The CHAOS-AF study

INTRODUCTION AND OBJECTIVES

The optimal approach for persistent atrial fibrillation (AF) ablation remains unknown. In patients with persistent AF, we compared an ablation strategy based on pulmonary vein isolation (PVI) plus ablation of drivers (PVI+D), with a conventional PVI-only approach performed in a 1:1 propensity score-matched cohort.

METHODS

Drivers were subjectively identified using conventional high-density mapping catheters (IntellaMap ORION, PentaRay NAV or Advisor HD Grid), without dedicated software, as fractionated continuous or quasicontinuous electrograms on 1 to 2 adjacent bipoles, which were ablated first; and as sites with spatiotemporal dispersion (the entire cycle length comprised within the mapping catheter) plus noncontinuous fractionation, which were only targeted in patients without fractionated continuous electrograms, or without AF conversion after ablation of fractionated continuous electrograms. Ablation included PVI plus focal or linear ablation targeting drivers.

RESULTS

A total of 50 patients were included in each group (61±10 years, 25% women). Fractionated continuous electrograms were found and ablated in 21 patients from the PVI+D group (42%), leading to AF conversion in 7 patients. In the remaining 43 patients, 143 sites with spatiotemporal dispersion plus noncontinuous fractionation were targeted. Globally, AF conversion was achieved in 21 patients (42%). The PVI+D group showed lower atrial arrhythmia recurrences at 1 year of follow-up (30.6% vs 48%; P=.048) and at the last follow-up (46% vs 72%; P=.013), and less progression to permanent AF (10% vs 40%; P=.001).

CONCLUSIONS

Subjective identification and ablation of drivers, added to PVI, increased 1-year freedom from atrial arrhythmia and decreased long-term recurrences and progression to permanent AF.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Ablation of persistent atrial fibrillation based on atrial electrogram duration map: methodology and clinical outcomes from the AEDUM pilot study

BACKGROUND

Catheter ablation of persistent atrial fibrillation (PsAF) represents a challenge for the electrophysiologist and there are still divergences regarding the best ablative approach to adopt. Create a new map of the duration of atrial bipolar electrograms (Atrial Electrogram DUration Map, AEDUM) to recognize a functional substrate during sinus rhythm and guide a patient-tailored ablative strategy for PsAF.

METHODS

Forty PsAF subjects were assigned in a 1:1 ratio to either for PVI alone (Group B1) or PVI+AEDUM areas ablation (Group B2). A cohort of 15 patients without AF history undergoing left-sided accessory pathway ablation was used as a control group (Group A). In all patients, voltage and AEDUM maps were created during sinus rhythm. The minimum follow-up was 12 months, with rhythm monitoring via 48-h ECG Holter or by implantable cardiac device.

RESULTS

Electrogram (EGM) duration was higher in Group B than in Group A (49±16.2ms vs 34.2±3.8ms; p-value<0.001). In Group B the mean cumulative AEDUM area was 21.8±8.2cm2; no difference between the two subgroups was observed (22.3±9.1cm2 vs 21.2±7.2cm2; p-value=0.45). The overall bipolar voltage recorded inside the AEDUM areas was lower than in the remaining atrial areas [median: 1.30mV (IQR: 0.71-2.38mV) vs 1.54mV (IQR: 0.79-2.97mV); p-value: <0.001)]. Low voltage areas (<0.5mV) were recorded in three (7.5%) patients in Group B. During the follow-up [median 511 days (376-845days)] patients who underwent PVI-only experienced more AF recurrence than those receiving a tailored approach (65% vs 35%; p-value= 0.04).

CONCLUSIONS

All PsAF patients exhibited AEDUM areas. An ablation approach targeting these areas resulted in a more effective strategy compared with PVI only.

Identification of Critical Slowing of Conduction Using Unipolar Atrial Voltage and Fractionation Mapping

BACKGROUND

Ablation strategies targeting fractionated or low-voltage potentials have been widely used in patients with persistent types of atrial fibrillation (AF). However, recent studies have questioned their role in effectively representing sites of conduction slowing, and thus arrhythmogenic substrates.

OBJECTIVES

The authors studied the relationship between local conduction velocity (CV) and the occurrence of fractionated and/or low-voltage potentials in order to identify areas with critically slowing of conduction.

METHODS

Intraoperative epicardial mapping was performed during sinus rhythm. Unipolar potentials with an amplitude <1.0 mV were initially classified as low-voltage and potentials with ≥3 deflections as fractionation. A range of thresholds were also explored. Local CV was computed using discrete velocity vectors.

RESULTS

A total of 319 patients were included. Fractionated, low-voltage potentials were rare, accounting for only 0.36% (Q1-Q3: 0.15%-0.78%) of all atrial sites. Local CV at sites with fractionated, low-voltage potentials (46.0 cm/s [Q1-Q3: 22.6-72.7 cm/s]) was lowest compared with sites with either low-voltage, nonfractionated potentials (64.5 cm/s [Q1-Q3: 34.8-99.4 cm/s]) or fractionated, high-voltage potentials (65.9 cm/s [Q1-Q3: 41.7-92.8 cm/s]; P < 0.001). Slow conduction areas (CV <50 cm/s) could be most accurately identified by using a low voltage threshold (<1 mV) and a minimum of 3 deflections (positive predictive value: 54.2%-70.7%), although the overall sensitivity remained low (0.1%-1.9%).

CONCLUSIONS

Sites with fractionated, low-voltage potentials have substantially slower local CV compared with sites with either low-voltage, nonfractionated potentials or fractionated, high-voltage potentials. However, the strong inverse relationship between the positive predictive value and sensitivity of a combined voltage and fractionation threshold for slowed conduction is likely to complicate the use of these signal-based ablation approaches in AF patients.

Atrial cardiomyopathy revisited-evolution of a concept: a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS)

AIMS

The concept of "atrial cardiomyopathy" (AtCM) had been percolating through the literature since its first mention in 1972. Since then, publications using the term were sporadic until the decision was made to convene an expert working group with representation from four multinational arrhythmia organizations to prepare a consensus document on atrial cardiomyopathy in 2016 (EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication). Subsequently, publications on AtCM have increased progressively.

METHODS AND RESULTS

The present consensus document elaborates the 2016 AtCM document further to implement a simple AtCM staging system (AtCM stages 1-3) by integrating biomarkers, atrial geometry, and electrophysiological changes. However, the proposed AtCM staging needs clinical validation. Importantly, it is clearly stated that the presence of AtCM might serve as a substrate for the development of atrial fibrillation (AF) and AF may accelerates AtCM substantially, but AtCM per se needs to be viewed as a separate entity.

CONCLUSION

Thus, the present document serves as a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS) to contribute to the evolution of the AtCM concept.

Discordant Treatment Goals for Patients With Atrial Fibrillation and Clinical Trials Metrics

BACKGROUND

Most clinical trials define successful atrial fibrillation (AF) treatment as no AF episodes longer than 30 seconds. Yet, there has been minimal study of how patients define successful treatment and whether their perspectives align with trial outcomes.

OBJECTIVES

Survey patients with AF to identify: 1) what aspect of AF is most important to address (frequency, duration, or severity of AF episodes); 2) what AF burden would be considered acceptable to consider treatment successful; and 3) to establish patient preferences for successful treatment thresholds for a validated patient-reported outcome (PRO) score.

METHODS

We surveyed patients receiving active care for AF at a single tertiary care center modeled after the Toronto AF Severity Scale (AFSS). The survey consisted of current and "successful treatment" AF frequency, burden, and symptom domains; and baseline socioeconomic information.

RESULTS

Of 7,000 invitations, 852 individuals completed the survey (12% response) with a mean age of 65 ± 13 years, 36.5% were female, and they had a mean CHA2DS2-VAsc score of 2.9 ± 1.9. Overall, 114 (13%) selected a decrease in AF episode duration as their top treatment priority, 505 (59%) episode frequency, and 230 (27%) episode severity. Overall, 207 (24%) patients would only consider a treatment successful if they never had AF again, whereas 645 (76%) patients considered success to be fewer AF episodes. A total of 341 (40%) patients would only consider a treatment successful if AF episodes lasted less than a few minutes, whereas 509 (60%) patients would accept AF episodes lasting >30 minutes. An AFSS symptom score ≤5 was considered a good outcome by 80% of respondents.

CONCLUSIONS

Patients prioritize decreased AF frequency over improvements in severity or duration, and an AFSS ≤5 would be a reasonable outcome of AF treatment. Most patients would consider treatment successful if they had more than 1 AF episode lasting longer than 30 seconds. Future clinical trial design should consider patients' perspectives when designing outcomes.

Low-Voltage Area Ablation in Addition to Pulmonary Vein Isolation in Patients with Atrial Fibrillation: A Systematic Review and Meta-Analysis

Background: Low-voltage area (LVA) ablation, in addition to pulmonary vein isolation (PVI), has been proposed as a new strategy in patients with atrial fibrillation (AF), but clinical trials have shown conflicting results. We performed a systematic review and meta-analysis to assess the impact of LVA ablation in patient undergoing AF ablation (PROSPERO-registered CRD42024537696). Methods: Randomized clinical trials investigating the role of LVA ablation in addition to PVI in patients with AF were searched on PubMed, Embase, and the Cochrane Library from inception to 22 April 2024. Primary outcome was atrial arrhythmia recurrence after the first AF ablation procedure. Secondary endpoints included procedure time, fluoroscopy time, and procedure-related complication rate. Sensitivity analysis including only patients with LVA demonstration at mapping and multiple subgroups analyses were also performed. Results: 1547 patients from 7 studies were included. LVA ablation in addition to PVI reduced atrial arrhythmia recurrence (odds ratio [OR] 0.65, 95% confidence interval [CI] 0.52-0.81, p < 0.001) with a number needed to treat to prevent recurrence of 10. No difference in procedure time (mean difference [MD] -5.32 min, 95% CI -19.01-8.46 min, p = 0.45), fluoroscopy time (MD -1.10 min, 95% CI -2.48-0.28 min, p = 0.12) and complication rate (OR 0.81, 95% CI 0.40-1.61, p = 0.54) was observed. Consistent results were demonstrated when considering only patients with LVA during mapping and in prespecified subgroups for AF type (paroxysmal vs. persistent), multicentric vs. monocentric trial, and ablation strategy in control group. Conclusions: In patients with AF, ablation of LVAs in addition to PVI reduces atrial arrhythmia recurrence without a significant increase in procedure time, fluoroscopy time, or complication rate.

Effects of antiarrhythmic drug responsiveness and diagnosis-to-ablation time on outcomes after catheter ablation for persistent atrial fibrillation

Background

The impact of delaying atrial fibrillation catheter ablation (AFCA) for antiarrhythmic drug (AAD) management on the disease course remains unclear. This study investigated AFCA rhythm outcomes based on the diagnosis-to-ablation time (DAT) and AAD responsiveness in participants with persistent AF (PeAF).

Methods

We included data from 1038 AAD-resistant PeAF participants, all of whom had a clear time point for AF diagnosis, especially PeAF at diagnosis time, and had undergone an AFCA for the first time. Participants who experienced recurrences of paroxysmal type on AAD therapy were analyzed as a cohort of AAD-partial responders; those maintaining PeAF on AAD were AAD-non-responders. We determined the DAT cutoff for best discriminating long-term rhythm outcomes using a maximum log-likelihood estimation method based on the Cox proportional hazard regression model.

Results

Of the participants (79.8% male; median age 61), 806 (77.6%) were AAD-non-responders. AAD-non-responders had a higher body mass index and a larger left atrial diameter than AAD-partial-responders. They also had a higher incidence of AF recurrence after AFCA (adjusted hazard ratio 1.75, 95% confidence interval 1.33-2.30; log-rank p < .001) compared to AAD-partial-responders. The maximum log-likelihood estimation showed bimodal cutoffs at 22 and 40 months. The optimal DAT cutoff rhythm outcome was 22 months, which discriminated better in the AAD-partial-responders than in the AAD-non-responders.

Conclusions

Both DAT and AAD responsiveness influenced AFCA rhythm outcomes. Delaying AFCA to a DAT of longer than 22 months was inadvisable, particularly in the participants in whom PeAF was changed to paroxysmal AF during AAD therapy.

Real-world evidence demonstrates an appropriate atrial fibrillation population for hybrid convergent approach versus stand-alone cryoballoon ablation: A long-term safety and efficacy study

INTRODUCTION

A hybrid convergent approach (endocardial and epicardial ablation) demonstrated superior effectiveness in a recent randomized study for long-standing persistent atrial fibrillation (LSPAF). Yet, there is a lack of real-world, long-term evidence as to which patients are best candidates for a hybrid convergent approach compared to standard endocardial cryoballoon pulmonary vein isolation (CB PVI).

METHODS AND RESULTS

This single-center, retrospective analysis spanning from 2010 to 2015 compared two distinctly different atrial fibrillation (AF) cohorts; one treated with stand-alone cryoablation and one treated with a hybrid convergent approach. Baseline characteristics described candidates for each approach. The following criteria were utilized to determine CB PVI candidacy: (1) paroxysmal AF (PAF) (stage 3A) with failed class I/III antiarrhythmic drug (AAD) or (2) persistent/LSPAF (stage 3B/3C/3D) with failed class I/III AAD unwilling to undergo hybrid procedure. Selection criteria for the hybrid procedure included: (1) PAF refractory to both class I/III AAD and prior CB PVI (stage 3D) or (2) persistent/LSPAF (stage 3B/3C/3D) with failed class I/III AAD agreeable to hybrid procedure. Prior sternotomy was excluded. Serial electrocardiograms and continuous monitoring evaluated primary efficacy outcome of time-to-first recurrence of atrial arrhythmia after a 90-day blanking period. Secondary outcomes were procedure-related complications and AAD use (at discharge, 12, and 36 months). Kaplan-Meier methods evaluated arrhythmia recurrence. Of 276 patients, 197 (64.2 ± 10.6 years old; 66.5% male; 74.1% 3A-PAF; 18.3% 3B/3D-persistent AF; 1.0% 3C-LSPAF; 6.6% undetermined) underwent CB PVI and 79 (61.4 ± 8.1 years old; 83.5% male; 41.8% 3D-PAF; 45.5% 3B/3D-persistent AF; 12.7% 3C/3D-LSPAF) underwent hybrid procedure. Arrhythmia freedom through 36 months was 55.2% for CB PVI and 50.4% for hybrid (p = .32). Class I AAD utilization at discharge occurred in 38 (19.3%) patients in the CB PVI group and 5 (6.3%) patients in the hybrid group (p = .01). CB PVI class I AAD utilization at 12 months occurred in 14 (9.0) patients versus 0 patients for hybrid convergent (p = .004). Patients with one or more adverse event were as follows: two (1.0%) in the CB PVI group (both transient phrenic nerve palsy) and three (3.7%) in the hybrid group (two with significant bleeding and one with wound infection) (p = .14).

CONCLUSION

This study demonstrated that patients with more complex forms of AF (3D-PAF or 3B/3C/3D-persistent/LSPAF) could be well managed with a convergent approach. In a real-world evaluation, outcomes match safety and efficacy thresholds achieved for patients with earlier, less complex AF etiologies treated by CB PVI alone.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

Case report of persistent atrial fibrillation with durably isolated pulmonary veins: what's next?

Background

Pulmonary vein isolation (PVI) has emerged as a safe and effective treatment for patients with paroxysmal and persistent atrial fibrillation. Nevertheless, in some patients, a relapse of atrial fibrillation occurs although pulmonary veins are durably isolated. For those patients, the underlying mechanisms of atrial fibrillation perpetuation are manifold and optimal treatment options are not yet defined.

Case summary

We describe a case of a 55-year-old man with a history of atrial fibrillation and previous PVI presenting with persistent AF and arrhythmia induced cardiomyopathy. During the redo procedure, electro-anatomical mapping revealed durably isolated PV. Bipolar mapping showed large low-voltage areas at the posterior wall and the septum. As the patient was refractory to electrical cardioversion, it was decided to modify the large low-voltage areas as potential arrhythmic substrate. After performing additional ablation with isolation of the posterior wall and two anterior/septal lines, the patient spontaneously converted to sinus rhythm.

Discussion

Ablation in patients with persistent AF despite durable PVI remains a challenge for the treating team. Individualized ablation approaches addressing additional arrhythmic substrates or extra-PV triggers can be considered to treat patients with persistent AF and durable PVI.

Adjunctive left atrial posterior wall isolation for atrial fibrillation: An updated systematic review and meta-analysis

OBJECTIVE

Posterior left atrial wall isolation (PWI) plus traditional pulmonary vein isolation (PVI) has been proposed as a promising intervention to decrease atrial fibrillation (AF) recurrence. We aim to investigate the efficacy and safety of adding PWI to the traditional PVI in patients with AF.

METHODS

A systematic review and meta-analysis was conducted using synthesizing randomized controlled trials (RCTs) retrieved by systematically searching PubMed, Web of Science, SCOPUS, EMBASE, and Cochrane through June 14, 2023. We used Stata version 17 to pool dichotomous data using risk ratio (RR) and continuous data using mean difference (MD), with a 95% confidence interval (CI) (PROSPERO ID: CRD42023446227).

RESULTS

We included 11 RCTs with a total number of 1534 patients. Combined ablation with PWI + PVI was not associated with any significant difference over PVI only regarding the recurrence of clinical AF (RR: 0.86 with 95% CI [0.70-1.06]), all atrial arrhythmia (RR: 0.93 with 95% CI [0.82-1.07]), nonatrial fibrillation arrhythmia (RR: 1.22 with 95% CI [0.97-1.53]), early AF (RR: 0.89 with 95% CI [0.62-1.27]), and antiarrhythmic drugs at discharge (RR: 0.83 with 95% CI [0.67-1.04]). However, it was associated with increased total ablation duration (minutes) (MD: 12.58 with 95% CI [6.80-18.37]) and total procedure duration (minutes) (MD: 16.77 with 95% CI [9.63-23.91]), without any significant difference regarding adverse events (RR: 1.05 with 95% CI [0.63-1.74]).

CONCLUSION

While the pooled data from PWI + PVI using point-by-point radiofrequency did not suggest a benefit in the recurrence of various atrial arrhythmias compared to PVI alone, PWI+PVI using direct posterior wall ablation, especially with cryoballoon, demonstrated a significant reduction in recurrence of AF/atrial arrhythmias. Also, PWI + PVI significantly increased the ablation and total procedure durations.

Leveraging 3D Atrial Geometry for the Evaluation of Atrial Fibrillation: A Comprehensive Review

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia associated with significant morbidity and mortality. Managing risk of stroke and AF burden are pillars of AF management. Atrial geometry has long been recognized as a useful measure in achieving these goals. However, traditional diagnostic approaches often overlook the complex spatial dynamics of the atria. This review explores the emerging role of three-dimensional (3D) atrial geometry in the evaluation and management of AF. Advancements in imaging technologies and computational modeling have enabled detailed reconstructions of atrial anatomy, providing insights into the pathophysiology of AF that were previously unattainable. We examine current methodologies for interpreting 3D atrial data, including qualitative, basic quantitative, global quantitative, and statistical shape modeling approaches. We discuss their integration into clinical practice, highlighting potential benefits such as personalized treatment strategies, improved outcome prediction, and informed treatment approaches. Additionally, we discuss the challenges and limitations associated with current approaches, including technical constraints and variable interpretations, and propose future directions for research and clinical applications. This comprehensive review underscores the transformative potential of leveraging 3D atrial geometry in the evaluation and management of AF, advocating for its broader adoption in clinical practice.

Factors predicting the recurrence of atrial fibrillation after catheter ablation: A review

Atrial fibrillation (AF) is the most common and clinically significant type of cardiac arrhythmia. Although catheter ablation (CA) can restore sinus rhythm in patients with AF, some patients experience recurrence after the procedure. This requires us to find a simple and effective way to identify patients at a high risk of recurrence and to intervene early in the high-risk population to improve patient prognosis. The mechanism of AF recurrence is unclear, but it involves several aspects including patient history, inflammation, myocardial fibrosis, and genes. This article summarizes the current predictors of AF recurrence after CA, including myocardial fibrosis markers, inflammatory markers, MicroRNAs, Circular RNAs, AF recurrence scores, and imaging indicators. Each predictor has its own scope of application, and the predictive capacity and joint application of multiple predictors may improve the predictive power. In addition, we summarize the mechanisms involved in AF recurrence. We hope that this review will assist researchers understand the current predictors of AF recurrence and help them conduct further related studies.

Contact-force local impedance algorithm to guide effective pulmonary vein isolation in AF patients: 1-year outcome from an international multicenter clinical setting

BACKGROUND

The combination of highly localized impedance (LI) and contact force (CF) may improve tissue characterization and lesion prediction during radiofrequency (RF) pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF).

OBJECTIVE

We report the outcomes of our acute and long-term clinical evaluation of CF-LI-guided PVI in consecutive AF ablation cases from an international multicenter clinical setting.

METHODS

Three hundred twenty-four consecutive patients from 20 European centers undergoing RF catheter ablation with the Stablepoint™ catheter were enrolled in the CHARISMA registry. Of these, 275 had a minimum follow-up of 1 year and were included in the primary analysis.

RESULTS

The mean procedure duration was 115 ± 47 min, and the mean fluoroscopy time was 9.9 ± 6 min. At the end of the procedures, all PVs had been successfully isolated in all study patients. Minor complications were reported in 12 patients (4.4%). At 1 year, 36 (13.1%) patients had had an AF recurrence, and freedom from antiarrhythmic drugs and AF recurrence was achieved in 228 (82.9%) patients. The recurrence rate was higher in patients with persistent AF (21/116, 18.1%) than in those with paroxysmal AF (15/159, 9.4%; p = 0.0459). On multivariate logistic analysis adjusted for baseline confounders, only time > 6 months from first diagnosis of AF to ablation (HR = 2.93, 95%CI 1.03 to 8.36, p = 0.0459) was independently associated with recurrences.

CONCLUSION

An ablation strategy for PVI guided by CF-LI technology proved safe and effective and resulted in a low recurrence rate of AF over 1-year follow-up, irrespective of the underlying AF type.

CLINICAL TRIAL REGISTRATION

Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice. (CHARISMA). URL: http://clinicaltrials.gov/ Identifier: NCT03793998.

Sex difference in atrial scar prevalence: What can we learn from the STABLE-SR-III trial?

BACKGROUND

Female sex has long been recognized to present a higher risk of stroke and atrial fibrillation (AF) recurrence after circumferential pulmonary vein isolation (CPVI) than in males. However, the underlying mechanisms and benefits of additional low-voltage area (LVA) modification in women remain unknown.

OBJECTIVE

The purpose of this study was to investigate differences in atrial substrate and efficacy of additive LVA ablation between sex subgroups.

METHODS

Patients with paroxysmal atrial fibrillation (PAF) aged 65-80 years were randomly assigned to either CPVI plus LVA modification (STABLE-SR) group or CPVI alone group. The primary outcome was freedom from atrial arrhythmias after a single ablation procedure.

RESULTS

Of 414 patients included in STABLE-SR-III, 204 (49.3%) were women (mean age 70.5 ± 4.7 years). Women demonstrated significantly higher LVA prevalence (51.5% vs 32.9%; P <.001) and LVA burden (6.5% vs 2.9%; P <.001) than men. In the STABLE-SR group, additional LVA ablation was associated with a 63% reduction in recurrence for women compared with the CPVI alone group (10.8% vs 29.4%; adjusted hazard ratio 0.37; 95% confidence interval 0.18-0.75; P for interaction = .040). However, this finding was not observed in men (18.7% vs 18.5%). In the female subgroup, both group 1 (CPVI + LVA modification) and group 3 (CPVI alone in females without LVA) had similar clinical outcomes, which were much better than in Group 2 (CPVI alone in women with LVA) (90% vs 83.8% vs 63.6%; P = .003).

CONCLUSION

In older patients with PAF, women demonstrated more advanced atrial substrate, including higher prevalence and burden of LVA compared with men. Women may receive greater benefit from additional LVA modification than men.

Assessing the arrhythmogenic propensity of fibrotic substrate using digital twins to inform a mechanisms-based atrial fibrillation ablation strategy

Atrial fibrillation (AF), the most common heart rhythm disorder, may cause stroke and heart failure. For patients with persistent AF with fibrosis proliferation, the standard AF treatment-pulmonary vein isolation-has poor outcomes, necessitating redo procedures, owing to insufficient understanding of what constitutes good targets in fibrotic substrates. Here we present a prospective clinical and personalized digital twin study that characterizes the arrhythmogenic properties of persistent AF substrates and uncovers locations possessing rotor-attracting capabilities. Among these, a portion needs to be ablated to render the substrate not inducible for rotors, but the rest (37%) lose rotor-attracting capabilities when another location is ablated. Leveraging digital twin mechanistic insights, we suggest ablation targets that eliminate arrhythmia propensity with minimum lesions while also minimizing the risk of iatrogenic tachycardia and AF recurrence. Our findings provide further evidence regarding the appropriate substrate ablation targets in persistent AF, opening the door for effective strategies to mitigate patients' AF burden.

Hybrid-Convergent Procedure or Pulsed Field Ablation in Long-Standing Persistent Atrial Fibrillation

BACKGROUND

Hybrid-convergent radiofrequency (RF) ablation targeting pulmonary veins (PVs) and left atrial posterior wall (LAPW) has shown better arrhythmic outcomes than an endocardial-only RF strategy, despite higher rates of complications. Comparisons with extensive pulsed field ablation (PFA) are currently lacking.

OBJECTIVES

This study aimed to compare the efficacy and safety of the hybrid-convergent RF vs PFA of PVs and LAPW in long-standing persistent atrial fibrillation (LSPAF).

METHODS

Ninety-three consecutive LSPAF patients, treated with 2-step hybrid-convergent RF ablation (hybrid group, n = 49) or with PFA of PVs and LAPW (PFA group, n = 44) were enrolled. Primary efficacy endpoint was defined as any atrial tachyarrhythmias (ATA) recurrence after the 3-month blanking period, over a follow-up time of 12 months. Periprocedural adverse events and late complications during follow-up were deemed primary safety outcomes.

RESULTS

The hybrid and PFA groups had similar baseline characteristics; mean age was hybrid 63.8 ± 10.6 years vs PFA 66.0 ± 7.4 years; P = 0.105. PV and LAPW ablation were acutely successful in all patients. Step 1 hybrid-epicardial procedures were longer than PFA (166 [Q1-Q3: 140-205] minutes vs 107.5 [Q1-Q3: 82.5-12] minutes; P < 0.01). At 12-month follow-up, there was no difference in ATA recurrences between groups (hybrid 36.7% vs PFA 40.9%; P = 0.680; log-rank at survival analysis P = 0.539). After adjusting for confounders, a larger left atrial volume and recurrences during the blanking-period were predictors of ATA recurrences after ablation, regardless of procedural technique employed. PFA showed a better safety profile with a lower rate of major periprocedural complications compared with hybrid ablation (12% vs 0%; P = 0.028).

CONCLUSIONS

Hybrid-convergent and PFA share comparable arrhythmic outcomes in LSPAF, but hybrid-convergent ablation carries higher periprocedural risks.

Adjunctive low-voltage area ablation for patients with atrial fibrillation: An updated meta-analysis of randomized controlled trials

BACKGROUND

The efficacy and safety of adjunctive low-voltage area (LVA) ablation on outcomes of catheter ablation (CA) for atrial fibrillation (AF) remains uncertain.

METHODS

PubMed, Embase, Cochrane Library, and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) comparing CA with versus without LVA ablation for patients with AF. Risk ratios (RR) with 95% confidence intervals (CI) were pooled with a random-effects model. Our primary endpoint was recurrence of atrial tachyarrhythmia (ATA), including AF, atrial flutter, or atrial tachycardia. We used R version 4.3.1 for all statistical analyses.

RESULTS

Our meta-analysis included 10 RCTs encompassing 1780 patients, of whom 890 (50%) were randomized to LVA ablation. Adjunctive LVA ablation significantly reduced recurrence of ATA (RR 0.76; 95% CI 0.67-0.88; p < .01) and reduced the number of redo ablation procedures (RR 0.54; 95% CI 0.35-0.85; p < .01), as compared with conventional ablation. Among 691 (43%) patients with documented LVAs on baseline substrate mapping, adjunctive LVA ablation substantially reduced ATA recurrences (RR 0.57; 95% CI 0.38-0.86; p < .01). There was no significant difference between groups in terms of periprocedural adverse events (RR 0.78; 95% CI 0.39-1.56; p = .49).

CONCLUSIONS

Adjunctive LVA ablation is an effective and safe strategy for reducing recurrences of ATA among patients who undergo CA for AF.

Impact of Posterior Wall Isolation During AF Ablation on the Incidence of Left Atrial Flutter

BACKGROUND

Linear and complex electrogram ablation (LCEA) beyond pulmonary vein isolation (PVI) is associated with an increase in left atrial macro-re-entrant tachycardias (LAMTs). Posterior wall isolation (PWI) is increasingly performed to improve AF ablation outcomes. However, the impact of PWI on the incidence of LAMT is unknown.

OBJECTIVES

The purpose of this study was to establish the incidence of LAMT following PVI alone vs PVI + PWI vs PVI + PWI + LCEA.

METHODS

Consecutive patients undergoing catheter ablation for AF or LAMT post-AF ablation between 2008 and 2022 from 4 electrophysiology centers were reviewed with a minimum follow-up of 12 months.

RESULTS

In total, 5,619 (4,419 index, 1,100 redo) AF ablation procedures were performed in 4,783 patients (mean age 60.9 ± 10.6 years, 70.7% men). Over a mean follow-up of 6.4 ± 3.8 years, 246 procedures for LAMT were performed in 214 patients at a mean of 2.6 ± 0.6 years post-AF ablation. Perimitral (52.8% of patients), roof-dependent (27.1%), PV gap-related (17.3%), and anterior circuits (8.9%) were most common, with 16.4% demonstrating multiple circuits. The incidence of LAMT was significantly higher following PVI + PWI (6.2%) vs PVI alone (3.0%; P < 0.0001) and following PVI + PWI + LCEA vs PVI + PWI (12.5%; P = 0.019). Conduction gaps in previous ablation lines were responsible for LAMT in 28.4% post-PVI alone, 35.3% post-PVI + PWI (P = 0.386), and 81.8% post-PVI + PWI + LCEA (P < 0.005).

CONCLUSIONS

The incidence of LAMT following PVI + PWI is higher than with PVI alone but significantly lower than with more extensive atrial substrate modification. Given a low frequency of LAMT following PWI, empiric mitral isthmus ablation is not justified and may be proarrhythmic.

Real world risk of discontinuing oral anticoagulation after successful catheter ablation for atrial fibrillation

Background

Many patients with atrial fibrillation (AF) discontinued oral anticoagulation (OAC) therapy after successful catheter ablation. We aimed to determine the real-world risks and consequences of discontinuing OAC use after catheter ablation for AF.

Methods

Patients who underwent successful catheter ablation for AF from January 2004 to December 2020 were divided into continued long-term OAC (On-OAC, n = 1062) and discontinued (Off-OAC, n = 1055) groups. The long-term outcomes including thromboembolic events, major bleeding, all-cause mortality and major adverse cardiovascular events (MACE), were compared between the two groups.

Results

The CHA2DS2-VASc score was 3.44 ± 1.12. After a mean follow-up of 37.09 months, thromboembolism risk was higher and major bleeding risk was lower in the Off-OAC than in the On-OAC group (Both log-rank P < 0.001). CHA2DS2-VASc score-stratified subgroup analysis showed similar cumulative event rates between the two groups in men and women with scores of 2 and 3 (intermediate risk for stroke), respectively, (P > 0.05), except for a higher major bleeding rate in the On-OAC group (P = 0.002). Patients at high risk for stroke (men and women with scores ≥3 and ≥ 4) had better non-thromboembolic and non-MACE results (Both log-rank P < 0.05).

Conclusion

Men with a CHA2DS2-VASc score of 2 and women with a score of 3 had a relatively low incidence of stroke events after successful catheter ablation for AF and may be safe for anticoagulation cessation. Greater benefits from long-term OAC were observed in men with CHA2DS2-VASc score ≥3 and women with score ≥4.

Chinese guidelines for the diagnosis and management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of the guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice timely and fully, the Chinese Society of Cardiology of Chinese Medical Association and the Heart Rhythm Committee of Chinese Society of Biomedical Engineering jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2‑VASc‑60 stroke risk score based on the characteristics of the Asian AF population. The guidelines also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

The Value of Adjunctive Left Atrial Posterior Wall Isolation on Clinical Outcomes in Atrial Fibrillation Patients: A Systematic Review and Meta-Analysis

Background

Although pulmonary vein isolation (PVI) remains the mainstream way of atrial fibrillation (AF) ablation. The left atrial posterior wall (LAPW) may contributes to the development of AF as an arrhythmogenic substrate. The efficacy of additional left atrial posterior wall isolation (LAPWI) beyond PVI is in AF patients remains undefined. This study explored the influence of posterior wall isolation (PWI) on clinical outcomes in AF patients.

Methods

PubMed, EMBASE, and Cochrane Library databases were searched for studies comparing the outcomes of AF with and without PWI. The efficacy outcomes were recurrence of all atrial arrhythmia (AA), atrial fibrillation (AF), and atrial flutter (AFL)/atrial tachycardia (AT). The safety outcomes were mainly focused on procedural adverse events.

Results

A total of 16 studies (7 randomized controlled trials (RCTs), 3 prospective studies and 6 retrospective analyses) with 3340 AF patients were enrolled (1550 patients in PVI with PWI group and 1790 in PVI alone group). 12 studies included persistent atrial fibrillation patients, 3 studies with paroxysmal AF patients and 1 study with paroxysmal AF and persistent AF concurrently. Mean follow-up period was 16.56 months. In AF patients, adjunctive PWI obviously reduced the recurrence of all atrial arrhythmias (risk ratio (RR) 0.78 [95% CI 0.64-0.95], I 2 = 79%, p = 0.01) and the recurrence of AF (RR 0.68 [95% CI 0.53-0.88], I 2 = 75%, p = 0.004); Meanwhile, additional PWI left no impact substantially on lower recurrence of AFL/AT (RR 1.23 [95% CI 0.94-1.60], I 2 = 49%, p = 0.12). The results seemed to be no significant differences in occurrence rate of procedural complications between the PVI only and PWI+PVI (RR 1.19 [95% CI 0.80-1.79], I 2 = 0%, p = 0.39). In subgroup analyses, the benefit of adjunctive PWI compared with PVI only was more distinct in persistent AF group and cryoballoon ablation group. Notably, adjunctive PWI with radiofrequency ablation may induce a slight increase of recurrent AFL/AT compared with PVI only (RR 1.56 [95% CI 1.02-2.39], I 2 = 30%, p = 0.04).

Conclusions

Compared with PVI alone, additional PWI to PVI appeared to be associated with decreased recurrence of AF and atrial arrhythmias without an increased occurrence of procedural complications, especially in persistent AF patients. Cryoballoon ablation seemed more suitable for PWI compared with radiofrequency ablation. More RCTs are needed to verify the conclusion.

2023 Cardiac Society of Australia and New Zealand Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has increased exponentially in many developed countries, including Australia and New Zealand. This Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation from the Cardiac Society of Australia and New Zealand (CSANZ) recognises healthcare factors, expertise and expenditure relevant to the Australian and New Zealand healthcare environments including considerations of potential implications for First Nations Peoples. The statement is cognisant of international advice but tailored to local conditions and populations, and is intended to be used by electrophysiologists, cardiologists and general physicians across all disciplines caring for patients with AF. They are also intended to provide guidance to healthcare facilities seeking to establish or maintain catheter ablation for AF.

Left atrial low-voltage areas, but not volume, predict the recurrence of atrial fibrillation in repeat ablation procedures

INTRODUCTION

Left atrial (LA) low voltage areas (LVA) are a controversial target in atrial fibrillation ablation procedures. However, LVA and LA volume are good predictors of arrhythmia recurrence in ablation-naïve patients. Their predictive value in progressively diseased pre-ablated atria is uncertain.

METHODS

Consecutive patients with recurrent atrial fibrillation (AF) or atrial tachycardia (AT), who were scheduled for repeat LA ablation, were enrolled in the prospective Bernau ablation registry between 2016 and 2020. All patients received a complete LA ultrahigh-density map before ablation. Maps were analyzed for LA size, LVA percentage and distribution. The predictive value of demographic, anatomic, and mapping variables on AF recurrence was analyzed.

RESULTS

160 patients (50.6% male, 1.3 pre-ablations, 60% persistent AF) with complete LA voltage maps were included. Mean follow-up time was 16 ± 11 months. Mean recorded electrograms (EGMs) per map were 9754 ± 5808, mean LA volume was 176.1 ± 35.9 ml and mean rate of LVAs <0.5 mV was 30.6% ± 23.1%. During follow-up recurrence rate of AF or AT >30 s was 55.6%. Patients with recurrence had a significant higher percentage of LVAs (40.0% vs. 18.8%, p < .001) but no relevant difference in LA volume (172 vs. 178 mL, p = .299). ROC curves revealed LVA as a good predictor for recurrence (AUC = 0.79, p < .001) and a cut-off of 22% LVAs with highest sensitivity (73.0%) and specificity (71.8%). Based on this cut off, event free survival was significantly higher in the Low LVA group (p < .01).

CONCLUSION

Total LVA percentage has a good predictive power on arrhythmia recurrence in a cohort of advanced scarred left atria in repeat procedures independent of the applied ablation strategy. Left atrial volume seems to have minor impact on the rhythm outcome in our study cohort.

Imaging of Cardiac Fibrosis: An Update, From the AJR Special Series on Imaging of Fibrosis

Myocardial fibrosis (MF) is defined as excessive production and deposition of extra-cellular matrix proteins that result in pathologic myocardial remodeling. Three types of MF have been identified: replacement fibrosis from tissue necrosis, reactive fibrosis from myocardial stress, and infiltrative interstitial fibrosis from progressive deposition of nondegradable material such as amyloid. Although echocardiography, nuclear medicine, and CT play important roles in the assessment of MF, MRI is pivotal in the evaluation of MF, with the late gadolinium enhancement (LGE) technique used as a primary end point. The LGE technique focuses on the pattern and distribution of gadolinium accumulation in the myocardium and assists in the diagnosis and establishment of the cause of both ischemic and nonischemic cardiomyopathy. LGE MRI also aids prognostication and risk stratification. In addition, LGE MRI is used to guide the management of patients considered for ablation for arrhythmias. Parametric mapping techniques, including T1 mapping and extracellular volume measurement, allow detection and quantification of diffuse fibrosis, which may not be detected by LGE MRI. These techniques also allow monitoring of disease progression and therapy response. This review provides an update on the imaging of MF, including prognostication and risk stratification tools, electrophysiologic considerations, and disease monitoring.

Predictors of low-voltage zones in patients with persistent atrial fibrillation eligible for catheter ablation: An observational study

INTRODUCTION

The presence of low-voltage zones (LVZs) in the left atrium (LA) is associated with the recurrence of atrial fibrillation (AF) following pulmonary vein isolation (PVI). However, there is variability and conflict in the data regarding predictors of LVZs as reported in previous studies. The objective of this study was to identify predictors for the presence of LVZs in a cohort of patients with persistent AF.

METHODS

The study prospectively enrolled 439 patients with persistent AF who were scheduled for ablation. Voltage map of the LA was collected using a multipolar catheter. An LVZ was defined as an area of ≥3 cm2 exhibiting a peak-to-peak bipolar voltage of <0.5 mV.

RESULTS

The mean age of the cohort was 65.3 ± 8.6 years and 26.4% were female. Additionally, 25.7% had significant LVZs, most frequently located in the anterior wall of the LA. Multivariable analysis identified the following independent predictors for LVZ: advanced age (OR [odds ratio] = 1.08, 95% CI [confidence interval] = 1.03-1.13, p = .002); female sex (OR = 4.83, 95% CI = 2.66-8.76, p < .001); coronary artery disease (CAD) (OR = 3.20, 95% CI = 1.32-7.77, p = .01) and enlarged LA diameter (OR = 1.10, 95% CI = 1.04-1.17, p = .001). The area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the final model was 0.829.

CONCLUSION

Approximately 25% of the patients with persistent AF had LVZs. Advanced age, female sex, CAD, and a larger LA were independent predictors for LVZs with the model demonstrating a very good AUC for the ROC curve. These findings hold the potential to be used to tailor the ablation procedure for the individual patient.

Patient-specific multi-physics simulations of fibrotic changes in left atrial tissue mechanics impact on hemodynamics

Stroke is a leading cause of death and disability worldwide. Atrial myopathy, including fibrosis, is associated with an increased risk of ischemic stroke, but the mechanisms underlying this association are poorly understood. Fibrosis modifies myocardial structure, impairing electrical propagation and tissue biomechanics, and creating stagnant flow regions where clots could form. Fibrosis can be mapped non-invasively using late gadolinium enhancement magnetic resonance imaging (LGE-MRI). However, fibrosis maps are not currently incorporated into stroke risk calculations or computational electro-mechano-fluidic models. We present multi-physics simulations of left atrial (LA) myocardial motion and hemodynamics using patient-specific anatomies and fibrotic maps from LGE-MRI. We modify tissue stiffness and active tension generation in fibrotic regions and investigate how these changes affect LA flow for different fibrotic burdens. We find that fibrotic regions and, to a lesser extent, non-fibrotic regions experience reduced myocardial strain, resulting in decreased LA emptying fraction consistent with clinical observations. Both fibrotic tissue stiffening and hypocontractility independently reduce LA function, but together, these two alterations cause more pronounced effects than either one alone. Fibrosis significantly alters flow patterns throughout the atrial chamber, and particularly, the filling and emptying jets of the left atrial appendage (LAA). The effects of fibrosis in LA flow are largely captured by the concomitant changes in LA emptying fraction except inside the LAA, where a multi-factorial behavior is observed. This work illustrates how high-fidelity, multi-physics models can be used to study thrombogenesis mechanisms in a patient-specific manner, shedding light onto the link between atrial fibrosis and ischemic stroke.

Key points

Left atrial (LA) fibrosis is associated with arrhythmogenesis and increased risk of ischemic stroke; its extent and pattern can be quantified on a patient-specific basis using late gadolinium enhancement magnetic resonance imaging.Current stroke risk prediction tools have limited personalization, and their accuracy could be improvedfib by incorporating patient-specific information like fibrotic maps and hemodynamic patterns.We present the first electro-mechano-fluidic multi-physics computational simulations of LA flow, including fibrosis and anatomies from medical imaging.Mechanical changes in fibrotic tissue impair global LA motion, decreasing LA and left atrial appendage (LAA) emptying fractions, especially in subjects with higher fibrosis burdens.Fibrotic-mediated LA motion impairment alters LA and LAA flow near the endocardium and the whole cavity, ultimately leading to more stagnant blood regions in the LAA.

Targeting the Substrate for Atrial Fibrillation: JACC Review Topic of the Week

The identification of the pulmonary veins as a trigger source for atrial fibrillation (AF) has established pulmonary vein isolation (PVI) as a key target for AF ablation. However, PVI alone does not prevent recurrent AF in many patients, and numerous additional ablation strategies have failed to improve on PVI outcomes. This therapeutic limitation may be due, in part, to a failure to identify and intervene specifically on the pro-fibrillatory substrate within the atria and pulmonary veins. In this review paper, we highlight several emerging approaches with clinical potential that target atrial cardiomyopathy-the underlying anatomic, electrical, and/or autonomic disease affecting the atrium-in various stages of practice and investigation. In particular, we consider the evolving roles of risk factor modification, targeting of epicardial adipose tissue, tissue fibrosis, oxidative stress, and the inflammasome, along with aggressive early anti-AF therapy in AF management. Attention to combatting substrate development promises to improve outcomes in AF.

Autonomic neuronal modulations in cardiac arrhythmias: Current concepts and emerging therapies

The pathophysiology of atrial fibrillation and ventricular tachycardia that result in cardiac arrhythmias is related to the sustained complicated mechanisms of the autonomic nervous system. Atrial fibrillation is when the heart beats irregularly, and ventricular arrhythmias are rapid and inconsistent heart rhythms, which involves many factors including the autonomic nervous system. It's a complex topic that requires careful exploration. Cultivation of speculative knowledge on atrial fibrillation; the irregular rhythm of the heart and ventricular arrhythmias; rapid oscillating waves resulting from mistakenly inconsistent P waves, and the inclusion of an autonomic nervous system is an inconceivable approach toward clinical intricacies. Autonomic modulation, therefore, acquires new expansions and conceptions of appealing therapeutic intelligence to prevent cardiac arrhythmia. Notably, autonomic modulation uses the neural tissue's flexibility to cause remodeling and, hence, provide therapeutic effects. In addition, autonomic modulation techniques included stimulation of the vagus nerve and tragus, renal denervation, cardiac sympathetic denervation, and baroreceptor activation treatment. Strong preclinical evidence and early human studies support the annihilation of cardiac arrhythmias by sympathetic and parasympathetic systems to transmigrate the cardiac myocytes and myocardium as efficient determinants at the cellular and physiological levels. However, the goal of this study is to draw attention to these promising early pre-clinical and clinical arrhythmia treatment options that use autonomic modulation as a therapeutic modality to conquer the troublesome process of irregular heart movements. Additionally, we provide a summary of the numerous techniques for measuring autonomic tone such as heart rate oscillations and its association with cutaneous sympathetic nerve activity appear to be substitute indicators and predictors of the outcome of treatment.

Pre- and post-procedural cardiac imaging (computed tomography and magnetic resonance imaging) in electrophysiology: a clinical consensus statement of the European Heart Rhythm Association and European Association of Cardiovascular Imaging of the European Society of Cardiology

Imaging using cardiac computed tomography (CT) or magnetic resonance (MR) imaging has become an important option for anatomic and substrate delineation in complex atrial fibrillation (AF) and ventricular tachycardia (VT) ablation procedures. Computed tomography more common than MR has been used to detect procedure-associated complications such as oesophageal, cerebral, and vascular injury. This clinical consensus statement summarizes the current knowledge of CT and MR to facilitate electrophysiological procedures, the current value of real-time integration of imaging-derived anatomy, and substrate information during the procedure and the current role of CT and MR in diagnosing relevant procedure-related complications. Practical advice on potential advantages of one imaging modality over the other is discussed for patients with implanted cardiac rhythm devices as well as for planning, intraprocedural integration, and post-interventional management in AF and VT ablation patients. Establishing a team of electrophysiologists and cardiac imaging specialists working on specific details of imaging for complex ablation procedures is key. Cardiac magnetic resonance (CMR) can safely be performed in most patients with implanted active cardiac devices. Standard procedures for pre- and post-scanning management of the device and potential CMR-associated device malfunctions need to be in place. In VT patients, imaging-specifically MR-may help to determine scar location and mural distribution in patients with ischaemic and non-ischaemic cardiomyopathy beyond evaluating the underlying structural heart disease. Future directions in imaging may include the ability to register multiple imaging modalities and novel high-resolution modalities, but also refinements of imaging-guided ablation strategies are expected.

Comprehensive atrial fibrillation burden and symptom reduction post-ablation: insights from DECAAF II

AIMS

Traditional atrial fibrillation (AF) recurrence after catheter ablation is reported as a binary outcome. However, a paradigm shift towards a more granular definition, considering arrhythmic or symptomatic burden, is emerging. We hypothesize that ablation reduces AF burden independently of conventional recurrence status in patients with persistent AF, correlating with symptom burden reduction.

METHODS AND RESULTS

Ninety-eight patients with persistent AF from the DECAAF II trial with pre-ablation follow-up were included. Patients recorded daily single-lead electrocardiogram (ECG) strips, defining AF burden as the proportion of AF days among total submitted ECG days. The primary outcome was atrial arrhythmia recurrence. The AF severity scale was administered pre-ablation and at 12 months post-ablation. At follow-up, 69 patients had atrial arrhythmia recurrence and 29 remained in sinus rhythm. These patients were categorized into a recurrence (n = 69) and a no-recurrence group (n = 29). Both groups had similar baseline characteristics, but recurrence patients were older (P = 0.005), had a higher prevalence of hyperlipidaemia (P = 0.007), and had a larger left atrial (LA) volume (P = 0.01). There was a reduction in AF burden in the recurrence group when compared with their pre-ablation burden (65 vs. 15%, P < 0.0001). Utah Stage 4 fibrosis and diabetes predicted less improvement in AF burden. The symptom severity score at 12 months post-ablation was significantly reduced compared with the pre-ablation score in the recurrence group, and there was a significant correlation between the reduction in symptom severity score and the reduction in AF burden (R = 0.39, P = 0.001).

CONCLUSION

Catheter ablation reduces AF burden, irrespective of arrhythmia recurrence post-procedure. There is a strong correlation between AF burden reduction and symptom improvement post-ablation. Notably, elevated LA fibrosis impedes AF burden decrease following catheter ablation.

Functional substrate mapping of atrium in patients with atrial scar: A novel method to predict critical isthmus of atrial tachycardia

Atrial tachycardia (AT) is a common rhythm disorder, especially in patients with atrial structural abnormalities. Although voltage mapping can provide a general picture of structural alterations which are mainly secondary to prior ablations, surgery or pressure/volume overload, data is scarce regarding the functional characteristics of low voltage regions in the atrium to predict critical isthmus of ATs. Recently, functional substrate mapping (FSM) emerged as a potential tool to evaluate the functionality of structurally altered regions in the atrium to predict critical sites of reentry. Current evidence suggested a clear association between deceleration zones of isochronal late activation mapping (ILAM) during sinus/paced rhythm and critical isthmus of reentry in patients with left AT. Therefore, these areas seem to be potential ablation targets even not detected during AT. Furthermore, abnormal conduction detected by ILAM may also have a role to identify the potential substrate and predict atrial fibrillation outcome after pulmonary vein isolation. Despite these promising findings, the utility of such an approach needs to be evaluated in large-scale comparative studies. In this review, we aimed to share our experience and review the current literature regarding the use of FSM during sinus/paced rhythm in the prediction of re-entrant ATs and discuss future implications and potential use in patients with atrial low-voltage areas.

Epicardial Atrial Fat at Cardiac Magnetic Resonance Imaging and AF Recurrence after Transcatheter Ablation

The relationship between epicardial adipose tissue (EAT) and atrial fibrillation (AF) has gained interest in recent years. The previous literature on the topic presents great heterogeneity, focusing especially on computed tomography imaging. The aim of the present study is to determine whether an increased volume of left atrial (LA) EAT evaluated at routine pre-procedural cardiac magnetic resonance imaging (MRI) relates to AF recurrences after catheter ablation. A total of 50 patients undergoing AF cryoballoon ablation and pre-procedural cardiac MRI allowing quantification of LA EAT were enrolled. In one patient, the segmentation of LA EAT could not be achieved. After a median follow-up of 16.0 months, AF recurrences occurred in 17 patients (34%). The absolute volume of EAT was not different in patients with and without AF recurrences (10.35 mL vs. 10.29 mL; p-value = 0.963), whereas the volume of EAT indexed on the LA volume (EATi) was lower, albeit non-statistically significant, in patients free from arrhythmias (12.77% vs. 14.06%; p-value = 0.467). The receiver operating characteristic curve testing the ability of LA EATi to predict AF recurrence after catheter ablation showed sub-optimal performance (AUC: 0.588). The finest identified cut-off of LA EATi was 10.65%, achieving a sensitivity of 0.5, a specificity of 0.82, a positive predictive value of 0.59 and a negative predictive value of 0.76. Patients with values of LA EATi lower than 10.65% showed greater survival, free from arrhythmias, than patients with values above this cut-off (84% vs. 48%; p-value = 0.04). In conclusion, EAT volume indexed on the LA volume evaluated at cardiac MRI emerges as a possible independent predictor of arrhythmia recurrence after AF cryoballoon ablation. Nevertheless, prospective studies are needed to confirm this finding and eventually sustain routine EAT evaluation in the management of patients undergoing AF catheter ablation.

Vein of Marshall Ethanol Infusion for AF Ablation; A Review

The outcomes of persistent atrial fibrillation (AF) ablation are modest with various adjunctive strategies beyond pulmonary vein isolation (PVI) yielding largely disappointing results in randomised controlled trials. Linear ablation is a commonly employed adjunct strategy but is limited by difficulty in achieving durable bidirectional block, particularly at the mitral isthmus. Epicardial connections play a role in AF initiation and perpetuation. The ligament of Marshall has been implicated as a source of AF triggers and is known to harbour sympathetic and parasympathetic nerve fibres that contribute to AF perpetuation. Ethanol infusion into the Vein of Marshall, a remnant of the superior vena cava and key component of the ligament of Marshall, may eliminate these AF triggers and can facilitate the ease of obtaining durable mitral isthmus block. While early trials have demonstrated the potential of Vein of Marshall 'ethanolisation' to reduce arrhythmia recurrence after persistent AF ablation, further randomised trials are needed to fully determine the potential long-term outcome benefits afforded by this technique.

Association of extra-pulmonary vein triggers with low-voltage area and clinical recurrence in patients with atrial fibrillation undergoing catheter ablation

Background and Objectives

Although extra-pulmonary vein (PV) triggers (ExPVTs) play a role in atrial fibrillation (AF) recurrence after catheter ablation (AFCA), the mechanism is unknown. We explored whether the locations of ExPVTs were associated with low-voltage scar areas (LVAs).

Methods

Among 2255 consecutive patients who underwent a de novo AFCA, 1696 (male 72.1%, median 60 years old, paroxysmal 64.7%) were included who underwent isoproterenol provocation and voltage mapping of the left atrium (LA) during their procedures. We investigated the associations between ExPVTs and their mean LA voltage and colocalization of ExPVTs within LVAs (<0.2 mV).

Results

We observed ExPVTs in 181 (10.7%) patients (60 in the LA, 99 in the right atrium [RA], 16 biatrial, and 6 unmappable). A lower mean LA voltage was independently associated with the existence of ExPVTs (OR 0.77 per 1 SD mV increase, 95% CI 0.60-0.99, p = .039). Among 76 patients who had ExPVTs[LA], 43 (56.6%) had ExPVTs within LVAs. During a median of a 42-month follow-up, patients with ExPVTs had a higher AF recurrence than those without (HR 1.87, 95% CI 1.48-2.37, Log-rank p < .001), but colocalization of ExPVTs and LVAs (Log-rank p = .544) and the anatomical location of ExPVTs (Log-rank p = .084) did not affect the rhythm outcome.

Conclusions

The presence of ExPVTs was associated with low LA voltage and poor rhythm outcome post-AFCA, but the colocalization of ExPVTs and LVA in LA did not affect rhythm outcome.

Performance of Image-navigated and Diaphragm-navigated 3D Late Gadolinium-enhanced Cardiac MRI for the Assessment of Atrial Fibrosis

Purpose To perform a qualitative and quantitative evaluation of the novel image-navigated (iNAV) 3D late gadolinium enhancement (LGE) cardiac MRI imaging strategy in comparison with the conventional diaphragm-navigated (dNAV) 3D LGE cardiac MRI strategy for the assessment of left atrial fibrosis in atrial fibrillation (AF). Materials and Methods In this prospective study conducted between April and September 2022, 26 consecutive participants with AF (mean age, 61 ± 11 years; 19 male) underwent both iNAV and dNAV 3D LGE cardiac MRI, with equivalent spatial resolution and timing in the cardiac cycle. Participants were randomized in the acquisition order of iNAV and dNAV. Both, iNAV-LGE and dNAV-LGE images were analyzed qualitatively using a 5-point Likert scale and quantitatively (percentage of atrial fibrosis using image intensity ratio threshold 1.2), including testing for overlap in atrial fibrosis areas by calculating Dice score. Results Acquisition time of iNAV was significantly lower compared with dNAV (4.9 ± 1.1 minutes versus 12 ± 4 minutes, P < .001, respectively). There was no evidence of a difference in image quality for all prespecified criteria between iNAV and dNAV, although dNAV was the preferred image strategy in two-thirds of cases (17/26, 65%). Quantitative assessment demonstrated that mean fibrosis scores were lower for iNAV compared with dNAV (12 ± 8% versus 20 ± 12%, P < .001). Spatial correspondence between the atrial fibrosis maps was modest (Dice similarity coefficient, 0.43 ± 0.15). Conclusion iNAV-LGE acquisition in individuals with AF was more than twice as fast as dNAV acquisition but resulted in a lower atrial fibrosis score. The differences between these two strategies might impact clinical interpretation. ©RSNA, 2024.

Pulmonary vein isolation plus adjunctive therapy for the treatment of atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

Pulmonary vein isolation (PVI) is the primary technique for ablation of atrial fibrillation (AF). It is unclear whether adjunctive therapies in addition to PVI can reduce atrial arrhythmia recurrence (AAR) compared to PVI alone in patients with AF.

METHODS

A meta-analysis of randomized controlled trials comparing PVI plus an adjunctive therapy (autonomic modulation, linear ablation, non-pulmonary vein trigger ablation, epicardial PVI [hybrid ablation], or left atrial substrate modification) to PVI alone was conducted. The primary outcome was AAR. Cumulative odd's ratios (OR) and 95% confidence intervals (CI) were calculated for each treatment type.

RESULTS

Forty-six trials were identified that included 8,500 participants. The mean age (± standard deviation) was 60.2 (±4.1) years, and 27.2% of all patients were female. The mean follow-up time was 14.6 months. PVI plus autonomic modulation and PVI plus hybrid ablation were associated with a relative 53.1% (OR 0.47; 95% CI 0.32 to 0.69; p < 0.001) and 59.1% (OR 0.41; 95% CI 0.23 to 0.75; p = 0.003) reduction in AAR, respectively, compared to PVI alone. All categories had at least moderate interstudy heterogeneity except for hybrid ablation.

CONCLUSION

Adjunctive autonomic modulation and epicardial PVI may improve the effectiveness of PVI. Larger, multi-center randomized controlled trials are needed to evaluate the efficacy of these therapies.