Beyond Pulmonary Vein Isolation in Nonparoxysmal Atrial Fibrillation: Posterior Wall, Vein of Marshall, Coronary Sinus, Superior Vena Cava, and Left Atrial Appendage

The Genetic Mechanisms and Pathology of Atrial Fibrillation: A Narrative Review

Atrial fibrillation (AF), the most prevalent tachyarrhythmia worldwide, is a complex condition influenced by genetic, structural, and environmental factors. While AF in the elderly is often associated with underlying cardiac disease, early-onset or "lone" AF (LAF) exhibits a stronger genetic predisposition. Studies have identified both monogenic and polygenic contributors to AF risk. Monogenic mutations, inherited in Mendelian patterns, often affect ion channels and regulatory proteins, while polygenic variants modulate susceptibility and interact with environmental factors. Genome-wide association studies (GWAS) and exosome-wide association studies (ExWAS) have expanded our understanding of AF genetics, identifying numerous susceptibility loci, though challenges remain in linking these variants to specific molecular mechanisms. Pathophysiologically, AF results from a balance of triggers, drivers, and substrates. Triggers, such as ectopic foci in the pulmonary veins, initiate AF episodes, while structural and electrical remodeling perpetuates the arrhythmia. Fibrosis, atrial dilation, and tachycardia-induced remodeling promote reentry circuits and irregular conduction, increasing AF vulnerability. The interplay between genetic predisposition and remodeling processes underscores the complexity of AF maintenance, particularly in persistent AF forms. Emerging insights into AF genetics and pathophysiology highlight the need for personalized approaches to its prevention and management. Understanding genetic risk, combined with targeted therapies addressing structural and electrical remodeling, holds promise for improved patient outcomes. Future research into AF's molecular and genetic mechanisms will be key to advancing precision medicine in this field.

Radiofrequency catheter ablation for re-do procedure after single-shot pulmonary vein isolation with pulsed field ablation for paroxysmal atrial fibrillation: case report

Background

Catheter ablation is frequently used to manage recurrent atrial fibrillation (AF) resistant to drug therapy, with pulmonary vein isolation (PVI) as a key tactic. Pulsed field ablation (PFA) has emerged as an innovative technology for PVI but poses challenges for redo procedures.

Case presentation

We report on a 73-year-old female patient who experienced recurrent AF after initial successful PVI using a novel PFA technology and subsequently underwent radiofrequency catheter ablation during a repeat intervention. The reconnection of pulmonary veins was discovered primarily in the anterior region of the right superior PV and the superior portion of the left superior PV. An anatomically-based segmental approach and larger circumferential PVI, followed by additional linear ablations at non-PV trigger sites, proved decisive in preventing further recurrence of atrial tachycardia.

Conclusion

While PFA exhibits promise as a secure and efficient modality for PVI, it necessitates excellent contact quality to ensure lasting results. For patients experiencing AF recurrences post-PFI, expanded strategies incorporating both comprehensive PVI and linear ablations at targeted non-PV sites might enhance treatment outcomes.

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.

Posterior wall isolation via a multi-electrode radiofrequency balloon catheter: feasibility, technical considerations, endoscopic findings and comparison with cryoballoon technologies

BACKGROUND

Posterior wall (PW) isolation is an important adjunctive ablation target in patients with non-paroxysmal atrial fibrillation (AF). Traditionally performed with point-by-point radiofrequency (RF) ablation, PW isolation has also been performed with different cryoballoon technologies. We aimed at assessing the feasibility of PW isolation with the novel RF balloon catheter Heliostar™ (Biosense Webster, CA, USA).

METHODS

We prospectively enrolled 32 consecutive patients with persistent AF scheduled for first-time ablation with the Heliostar™ device. Procedural data were compared with those from 96 consecutive persistent AF patients undergoing pulmonary vein (PV) plus PW isolation with a cryoballoon device. The ratio RF balloon/cryoballoon was 1:3 for each operator involved in the study, aiming at avoiding any imbalance related to different experience.

RESULTS

Single-shot PV isolation was documented in a significantly higher number of cases with the RF balloon technology compared to cryoballoon ablation (89.8% vs. 81.0%; p = 0.02, respectively). PW isolation was achieved with a similar number of balloon applications between the two groups (11 ± 4 with the RF balloon versus 11 ± 2 with the cryoballoon; p = 0.16), but in a significantly shorter time among RF balloon patients (228 ± 72 s versus 1274 ± 277 s with cryoballoon; p < 0.001). Primary safety endpoint occurred in none of the RF balloon patients versus 5 (5.2%) patients in the cryoballoon group (p = 0.33). Primary efficacy endpoint was achieved in all (100%) RF balloon patients versus 93 (96.9%) cryoballoon ones (p = 0.57). Oesophageal endoscopy did not show any signs of thermal lesions in RF balloon patients with luminal temperature rise.

CONCLUSIONS

RF balloon-based PW isolation was safe and promoted shorter procedure times compared to similar cryoballoon-based ablation procedures.

Management of atrial fibrillation: two decades of progress - a scientific statement from the European Cardiac Arrhythmia Society

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice. The aim of this review was to evaluate the progress made in the management of AF over the two last decades.

RESULTS

Clinical classification of AF is usually based on the presence of symptoms, the duration of AF episodes and their possible recurrence over time, although incidental diagnosis is not uncommon. The majority of patients with AF have associated cardiovascular diseases and more recently the recognition of modifiable risk factors both cardiovascular and non-cardiovascular which should be considered in its management. Among AF-related complications, stroke and transient ischaemic accidents (TIAs) carry considerable morbidity and mortality risk. The use of implantable devices such as pacemakers and defibrillators, wearable garments and subcutaneous cardiac monitors with recording capabilities has enabled to access the burden of "subclinical AF". The recent introduction of non-vitamin K antagonists has led to improve the prevention of stroke and peripheral embolism. Agents capable of reversing non-vitamin K antagonists have also become available in case of clinically relevant major bleeding. Transcatheter closure of left atrial appendage represents an option for patients unable to take oral anticoagulation. When treating patients with AF, clinicians need to select the most suitable strategy, i.e. control of heart rate and/or restoration and maintenance of sinus rhythm. The studies comparing these two strategies have not shown differences in terms of mortality. If an AF episode is poorly tolerated from a haemodynamic standpoint, electrical cardioversion is indicated. Otherwise, restoration of sinus rhythm can be obtained using intravenous pharmacological cardioversion and oral class I or class III antiarrhythmic is used to prevent recurrences. During the last two decades after its introduction in daily practice, catheter ablation has gained considerable escalation in popularity. Progress has also been made in AF associated with heart failure with reduced or preserved ejection fraction.

CONCLUSIONS

Significant progress has been made within the past 2 decades both in the pharmacological and non-pharmacological managements of this cardiac arrhythmia.

Comparing the efficacy of catheter ablation strategies for persistent atrial fibrillation: a Bayesian analysis of randomized controlled trials

BACKGROUND

Catheter ablation has been recommended as the first-line treatment option for selected patients with atrial fibrillation (AF). However, a widely accepted ablation strategy for persistent AF (perAF) has not yet been established. The benefits of ablation strategies are not conclusive for perAF. There is an urgent need to systematically analyze the results of previous studies and rank these treatment strategies to guide clinical practice.

METHODS

Randomized controlled trials (RCTs) on ablation for perAF were included. The primary outcome was recurrence of atrial tachyarrhythmia (AT) after a single ablation procedure. A Bayesian random-effects network meta-analysis model was fitted.

RESULTS

Twenty-three studies were included in the analysis. A total of 3394 patients and 22 ablation strategies were found in the involved studies. The ablation strategy of pulmonary vein isolation (PVI) + electrical box isolation of the left atrial posterior wall (PBOX) + non-PV trigger ablation (NPV) showed the best treatment effect in terms of the primary outcome. The individualized ablation strategies of mapping and ablation combined with PVI, such as PVI + rotors, PVI + dispersion areas, and PVI + low voltage zone (LVZ) also showed a better ablation effect in perAF.

CONCLUSIONS

PVI ablation is a widely used strategy in perAF and is recognized as a cornerstone procedure for perAF. The PVI + PBOX + NPV strategy showed the highest rank in our analysis. Mapping and ablation strategies that could provide individualized substrate modification also showed a better rank in our analysis and are believed to be a promising direction for the treatment of perAF.

Exclusion of left atrial appendage: effects beyond thromboembolic prevention

PURPOSE OF REVIEW

This review aims to summarize the nonthromboembolic prevention effects of left atrial appendage exclusion (LAAE).

RECENT FINDINGS

Left atrial appendage (LAA) secretes multiple hormones; regulates blood volume and pressure; and generates trigger activities. Exclusion of the LAA by different techniques may lead to downstream effects including changes in blood pressure and cardiac performance, improvement of outcome of atrial fibrillation (AF) ablation, and alteration of metabolism.

SUMMARY

LAAE procedures not only prevent thromboembolic events in patients with AF, but rather may bring additional benefits or side-effect to patients undergoing LAAE.

Extra-Pulmonary Vein Triggers at de novo and the Repeat Atrial Fibrillation Catheter Ablation

Background: Extra-pulmonary vein triggers can play a significant role in atrial fibrillation recurrence after catheter ablation. We explored the characteristics of the extra-pulmonary vein (PV) triggers in de novo and repeat atrial fibrillation (AF) catheter ablation (AFCA).

Methods: We included 2,118 patients who underwent a de novo AFCA (women 27.6%, 59.2 ± 10.9 years old, paroxysmal AF 65.9%) and 227 of them conducted repeat procedures. All included patients underwent isoproterenol provocation tests at the end of the procedure, and then we analyzed extra-PV triggers-related factors.

Results: Extra-PV triggers were documented in 11.7% of patients undergoing de novo AFCA (1.22 ± 0.46 foci per patient) and 28.6% undergoing repeat AFCA (1.49 ± 0.73 foci per patient). Older age and higher LA volume index in de novo procedures and women, diabetes, and higher parasympathetic nerve activity (heart rate variability) in repeat-AFCA were independently associated with the existence of extra-PV triggers. The septum (19.9%), coronary sinus (14.7%), and superior vena cava (11.2%) were common extra-PV foci. Among 46 patients who were newly found to have mappable extra-PV triggers upon repeat procedures, 15 (32.6%) matched with the previous focal or empirical extra-PV ablation sites. The rate of AF recurrence was significantly higher in patients with extra-PV triggers than in those without after de novo (HR 1.91, 95% CI 1.54–2.38, p < 0.001) and repeat procedures (HR 2.68, 95% CI 1.63–4.42, p < 0.001).

Conclusions: Extra-PV triggers were commonly found in AF patients with significant remodeling and previous empirical extra-PV ablation. The existence of extra-PV triggers was independently associated with poorer rhythm outcomes after the de novo and repeat AFCA.