Anatomical targets and expected outcomes of catheter-based ablation of atrial fibrillation in 2020

Concurrent vs Staged Hybrid Ablation for Long-Standing Persistent Atrial Fibrillation: A Propensity-Matched Cohort Study

BACKGROUND

Long-term success rates of catheter ablation (CA) for long-standing persistent atrial fibrillation (LSPAF) are less than satisfactory. Further improvement of ablation methods is crucial for enhancing the treatment of LSPAF.

OBJECTIVE

This study sought to compare the outcomes of concurrent vs staged minimally invasive surgical-catheter hybrid ablation for LSPAF.

METHODS

From December 2015 to December 2021, 104 matched patients (concurrent and staged, 1:1) were included in study. In the concurrent group, both left unilateral thoracoscopic epicardial ablation (EA) and CA were performed simultaneously in one procedure. In the staged group, EA was performed at the first hospitalization. If the patients experienced atrial fibrillation (AF) recurrence, CA was performed between 3 months and 1 year after EA.

RESULTS

In the concurrent group, 4 patients were restored to sinus rhythm after EA, and 41 were patients restored to sinus rhythm during CA; 86.5% (45 of 52) achieved intraprocedural AF termination during concurrent hybrid ablation. In the staged group, all 52 patients underwent staged CA because of the recurrence of AF or atrial tachycardia (AT). Forty-seven (90.4%) patients achieved intraprocedural AF or AT termination during CA. Freedom from AF or AT off antiarrhythmic drugs at 2 years after hybrid ablation was 79.9% ± 5.7% in the concurrent group and 86.0% ± 4.9% in the staged group (P = 0.390). Failure of intraprocedural AF termination (HR: 14.378) was an independent risk factor for AF recurrence after hybrid ablation.

CONCLUSIONS

Both concurrent and staged hybrid ablation could be safely and effectively applied to treat LSPAF. Improving the intraprocedural AF termination rate predicted better outcomes.

Advances in basic and translational research in atrial fibrillation

Atrial fibrillation (AF) is a very common cardiac arrhythmia with an estimated prevalence of 33.5 million patients globally. It is associated with an increased risk of death, stroke and peripheral embolism. Although genetic studies have identified a growing number of genes associated with AF, the definitive impact of these genetic findings is yet to be established. Several mechanisms, including electrical, structural and neural remodelling of atrial tissue, have been proposed to contribute to the development of AF. Despite over a century of exploration, the molecular and cellular mechanisms underlying AF have not been fully established. Current antiarrhythmic drugs are associated with a significant rate of adverse events and management of AF using ablation is not optimal, especially in cases of persistent AF. This review discusses recent advances in our understanding and management of AF, including new concepts of epidemiology, genetics and pathophysiological mechanisms. We review the current status of antiarrhythmic drug therapy for AF, new potential agents, as well as mechanism-based AF ablation. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.

Mapping Technologies for Catheter Ablation of Atrial Fibrillation Beyond Pulmonary Vein Isolation

Catheter ablation remains the most effective and relatively minimally invasive therapy for rhythm control in patients with AF. Ablation has consistently shown a reduction of arrhythmia-related symptoms and significant improvement in patients’ quality of life compared with medical treatment. The ablation strategy relies on a well-established anatomical approach of effective pulmonary vein isolation. Additional anatomical targets have been reported with the aim of increasing procedure success in complex substrates. However, larger ablated areas with uncertainty of targeting relevant regions for AF initiation or maintenance are not exempt from the potential risk of complications and pro-arrhythmia. Recent developments in mapping tools and computational methods for advanced signal processing during AF have reported novel strategies to identify atrial regions associated with AF maintenance. These novel tools – although mainly limited to research series – represent a significant step forward towards the understanding of complex patterns of propagation during AF and the potential achievement of patient-tailored AF ablation strategies for the near future.

Novel approaches to mechanism-based atrial fibrillation ablation

Modern cardiac electrophysiology has reported significant advances in the understanding of mechanisms underlying complex wave propagation patterns during atrial fibrillation (AF), although disagreements remain. One school of thought adheres to the long-held postulate that AF is the result of randomly propagating wavelets that wonder throughout the atria. Another school supports the notion that AF is deterministic in that it depends on a small number of high-frequency rotors generating three-dimensional scroll waves that propagate throughout the atria. The spiralling waves are thought to interact with anatomic and functional obstacles, leading to fragmentation and new wavelet formation associated with the irregular activation patterns documented on AF tracings. The deterministic hypothesis is consistent with demonstrable hierarchical gradients of activation frequency and AF termination on ablation at specific (non-random) atrial regions. During the last decade, data from realistic animal models and pilot clinical series have triggered a new era of novel methodologies to identify and ablate AF drivers outside the pulmonary veins. New generation electroanatomical mapping systems and multielectrode mapping catheters, complimented by powerful mathematical analyses, have generated the necessary platforms and tools for moving these approaches into clinical procedures. Recent clinical data using such platforms have provided encouraging evidence supporting the feasibility of targeting and effectively ablating driver regions in addition to pulmonary vein isolation in persistent AF. Here, we review state-of-the-art technologies and provide a comprehensive historical perspective, characterization, classification, and expected outcomes of current mechanism-based methods for AF ablation. We discuss also the challenges and expected future directions that scientists and clinicians will face in their efforts to understand AF dynamics and successfully implement any novel method into regular clinical practice.