• electrophysiology
• ablation techniques

Atrial fibrillation (AF) is the most frequently encountered sustained cardiac arrhythmia that is associated with reduced quality of life (QOL) and increased risks of heart failure, cognitive impairment, stroke and death. Contemporary management of AF should primarily include optimal rhythm control strategy and stroke prevention in order to improve AF-related health outcome measures and patient satisfaction. In addition, modification of risk factors is important to consolidate treatment effects. Rate control with medication or ‘ablate and pace’ strategy should be reserved for patients with symptomatic AF in whom rhythm control is not a viable option.1 The major impact of AF on cardiovascular morbidity and mortality has driven the cardiac electrophysiology community to improve strategies to deliver therapies that are safe, effective and patient centred to timely restore and maintain sinus rhythm. Currently, the therapeutic armamentarium for rhythm control in patients with symptomatic AF includes anti-arrhythmic medication and catheter ablation. Catheter ablation has been shown to be superior to anti-arrhythmic drug therapy in maintaining sinus rhythm and reducing symptoms in patients with AF.2 3

It is generally accepted that the pathophysiology of AF includes a trigger to initiate AF, a substrate to maintain AF and modulating risk factors, ultimately resulting in progression to more persistent forms of AF. Over the years, AF ablation strategies have targeted elimination of AF triggers or modification of the arrhythmogenic substrate. Durable pulmonary vein (PV) isolation is the cornerstone of catheter ablation in patients with symptomatic paroxysmal AF.1 Despite advances in catheter-based AF ablation technologies, creation of durable lesions for pulmonary vein isolation (PVI) in a safe and effective way remains challenging. The AF recurrence rate after ablation remains relatively high mainly due to reconnection of PVs. Although 3D electroanatomical mapping-guided point-by-point radiofrequency (RF) ablation is the most commonly applied PVI technique, the procedure is still technically challenging, even in experienced centres. Potential complications associated with the RF point-by-point ablation technique include cardiac tamponade, thromboembolism, oesophageal damage including atrio-oesophageal fistulae, PV stenosis and atypical atrial flutters.

Over the past years, different catheter ablation systems using various energy sources, including 3D electroanatomical mapping-guided point-by-point RF ablation and balloon-based ‘single shot’ ablation technologies, such as Cryo and Laser and RF balloon ablation of the antrum of the PVs, have been developed to improve catheter handling, thereby enhancing safety, efficiency and efficacy of PVI procedures. Gupta and colleagues4 report their findings on post-PVI improvements in QOL and healthcare utilisation in patients with paroxysmal AF. This is an ancillary investigation of the VISTAX Study and the paper covers a currently important topic, namely to increase our understanding of the role of AF ablation and clinical outcome measures. This manuscript conveys an important message underlining the importance of a protocolised, that is, CLOSE (contiguous optimised lesions) algorithm-guided PVI as an effective rhythm control strategy to improve QOL and reduce AF disease burden. They4 used this specific PVI RF ablation technique to create durable contiguous circumferential ablation lesions at the antrum of the PVs. Patients with drug-resistant symptomatic paroxysmal AF were included in this non-randomised multicentre study and PVI procedures were performed in dedicated high-volume AF management centres. QOL was measured at baseline and 12 months post-ablation using Atrial Fibrillation Effect on QualiTy-of-life Questionnaire (AFEQT) and EQ-5D-5L questionnaires. The mean AFEQT score increased by 25.7, which is in line with the improvement in QOL observed in previous studies such as the CABANA trial.2–4 Although the majority of the patients included in the CABANA trial had persistent or longstanding persistent AF, the mean AFEQT score increase of 23.5 at 12 months post-ablation is very similar to the results of the VISTAX Study.2 4 Randomised clinical trials of medical and catheter ablation strategies clearly demonstrated a significant and clinically relevant improvement in QOL at 12 months after randomisation to catheter ablation compared with drug therapy.2 However, the effect of AF ablation on mortality is not well established yet. In the CASTLE AF trial,5 catheter ablation was associated with improved survival and reduced heart failure hospitalisations in patients with AF and heart failure. The CABANA trial failed to show significant survival benefit of catheter ablation compared with medical therapy.2 Meanwhile, symptom reduction and QOL improvement remain the primary indication for catheter ablation according to the European Society of Cardiology 2020 guidelines.1

Significant reduction of the impact of AF on healthcare utilisation and improvement of QOL metrics should be regarded as important and patient-relevant healthcare values gained by catheter ablation of paroxysmal AF. Moreover, Gupta and colleagues report an inverse association between the extent of QOL improvement and residual AF burden post-ablation.4 These results emphasise the importance of incorporating AF-specific QOL metrics in AF ablation studies.

Although this study was not designed to continuously monitor AF burden, a practical approach was chosen to estimate the symptomatic AF burden using serial Holter recordings and transtelephonic monitoring, which is not reflecting the real AF burden as determined by continuous cardiac monitoring using, for example, an implantable loop recorder system. Nevertheless, the outcomes elucidated the significant and clinically relevant impact of standardised point-by-point PVI on patient‐experienced AF disease burden by assessing subjective and objective outcome measures of AF disease burden, that is, validated AF-specific QOL metrics, repeat ablations and cardiovascular hospitalisations, which may be regarded as the outcome measures of ablative AF disease burden management.6 7 Do we need to consider an arrhythmia recurrence, defined as an ECG showing the characteristics of AF/atrial flutter/atrial tachycardia, or on a 30-second telemetry strip, as a failure of PVI? Or do we need to focus on AF disease burden reduction? The VISTAX Study highlights the increasing need to reconsider the optimal AF ablation study endpoint. The investigators identified higher pre-ablation AFEQT and CHA2DS2-VASc scores and higher AF burden post-ablation as predictors of failure treatment in this study.4 VISTAX-like studies provide important data that can be used as a source to measure robust clinical outcomes. They demonstrated that in experienced centres, standardised point-by-point PVI can be performed successfully and safely by skilled operators. There are numerous reports regarding outcomes of routine AF care, in particular anticoagulant therapy in the prevention of stroke. The VISTAX Study highlights the need for structured assessment of the QOL and AF disease burden as an integral part of the contemporary AF management pre-ablation and post-ablation.7

So, this subanalysis of the VISTAX Study provides intriguing data regarding the added value of catheter ablation in the comprehensive management of paroxysmal drug refractory AF. Although the CLOSE protocol-guided PVI was associated with an augmented arrhythmic outcome compared with data derived from randomised studies such as the Fire and Ice trial, the improvement in QOL and reduction of healthcare utilisation were comparable.4 6 8 The field of AF catheter ablation technologies is moving fast. Therefore, we need to put the VISTAX Study results of point-by-point RF PVI into perspective. In the next decade, this 3D mapping-guided protocolised point-by-point ablation algorithm for primo PVI may be regarded as a historical reference and will mainly be replaced by novel ‘single shot’ ablation technologies using different energy sources. This includes Cryo and Laser balloon systems, and last but not least irreversible electroporation (IRE) as a potentially promising ‘new kid on the block’, that is, non-thermal durable PVI using IRE pulses that create nanoscale pores in myocardial cell membranes without damaging surrounding structures, such as the oesophagus, nerves and arteries. The journey of innovations in AF ablation technologies will continue. In the meantime, the VISTAX Study conveys clinically relevant messages regarding the role of standardised PVI in paroxysmal AF disease management.