Biatrial mapping in persistent atrial fibrillation: new insights into drivers

Persistent atrial fibrillation (AF) is often treated as a disorder sustained by several interacting mechanisms rather than a single, stable source. Electrical remodelling, atrial fibrosis, conduction slowing, autonomic influences and progressive chamber enlargement can create a substrate in which wavefronts continually fragment and reorganise. This complexity helps explain why pulmonary vein isolation alone may be insufficient for some patients with long-standing disease.

Biatrial mapping offers a broader view of that substrate. Instead of examining the left atrium in isolation, electrophysiologists can assess activation, voltage, conduction velocity and rhythm organisation across both atria. The approach may reveal interatrial connections, right atrial regions and septal pathways that participate in maintenance of AF or influence the success of rhythm-control procedures.

The clinical value of these observations depends on careful interpretation. A mapped driver may represent a true sustaining mechanism, a by-product of wavefront collision, or an artefact caused by limited electrode coverage and signal processing. High-density contact mapping, panoramic systems and phase-based analysis each provide valuable information, yet none removes the need to link electrical findings with anatomy, imaging and patient-specific disease history.

For clinicians following developments in electrophysiology, the Journal of Arrhythmia provides access to research, reviews and clinical guidance relevant to atrial tachyarrhythmias. The emerging biatrial perspective is especially important as ablation strategies move towards more selective treatment of demonstrable substrate rather than broad empirical lesion sets.

Why the second atrium matters

The right and left atria are electrically connected through structures such as Bachmann’s bundle, the fossa ovalis region, the coronary sinus musculature and other septal pathways. These connections can support rapid propagation between chambers. During persistent AF, wavefronts entering or leaving the right atrium may help maintain irregular activation, even when the dominant abnormalities appear to be located in the left atrium.

Left atrial enlargement and fibrosis remain central features in many patients, particularly those with hypertension, obesity, sleep apnoea, valvular disease or heart failure. However, right atrial dilation, tricuspid regurgitation, pulmonary hypertension and right-sided pressure loading can add an important layer of disease. Biatrial electroanatomical mapping may identify low-voltage areas, delayed activation or conduction block in the right atrium that would be missed by a left-sided strategy alone.

This broader assessment may also clarify why some patients relapse after apparently complete pulmonary vein isolation. Recurrence can arise from pulmonary vein reconnection, but it may also reflect extra-pulmonary triggers, an extensive atrial substrate or coordinated activation across interatrial bridges. Mapping both chambers creates an opportunity to distinguish these possibilities before additional ablation is undertaken.

Reading electrical drivers with greater precision

Atrial drivers are described using several overlapping concepts, including focal discharges, rotational activity, re-entry, repetitive conduction patterns and areas of localised irregular activation. In persistent AF, these phenomena may be transient rather than fixed. A region that appears dominant during one recording period can lose prominence as wavefronts change direction, autonomic tone shifts or ablation alters conduction.

High-density multipolar catheters can improve spatial resolution and help identify short intervals of organised activity within an otherwise chaotic rhythm. Activation mapping can show propagation sequences, while voltage mapping highlights scar and diseased myocardium. Phase mapping and electrogram morphology analysis may add information about wavefront rotation or fractionation, although their results depend heavily on filtering, annotation rules, cycle length and the quality of tissue contact.

A credible driver should therefore demonstrate reproducibility and a plausible relationship with surrounding activation. It should be assessed across several beats, catheter positions and rhythm conditions where possible. Simultaneous or near-simultaneous recordings from both atria may be particularly useful for determining whether apparent focal activity is truly initiating propagation or simply reflecting passive activation from a neighbouring region.

Signal interpretation is a major limitation. Far-field electrograms, electrode spacing, catheter motion and incomplete endocardial coverage can create false discontinuities. Epicardial conduction, intramural bundles and the ligament of Marshall may also produce electrical behaviour that surface or endocardial mapping cannot fully resolve. These limitations argue for combining mapping data with cardiac magnetic resonance imaging, computed tomography, echocardiography and the clinical context.

From mapped substrate to ablation decisions

The practical aim of biatrial mapping is not to create larger lesion sets. It is to identify treatment targets with a reasonable mechanistic basis while preserving atrial function and reducing unnecessary tissue injury. Pulmonary vein isolation remains the foundation of catheter ablation for many patients, but additional ablation may be considered when mapping shows reproducible non-pulmonary triggers, discrete scar-related channels or organised atrial tachycardias.

Potential targets include the posterior wall, septal regions, the coronary sinus, the right atrial free wall and the left atrial appendage. Each carries specific risks and uncertain benefits. Extensive posterior wall ablation can affect the oesophagus, while coronary sinus and septal interventions may damage nearby conduction tissue. Left atrial appendage isolation can reduce electrical contribution from the appendage but may impair contractility and increase thromboembolic management requirements.

Driver-guided procedures must therefore be integrated with established endpoints. These include durable pulmonary vein isolation, termination or slowing of AF where appropriate, confirmation of bidirectional block across selected lines and assessment for induced atrial tachycardia. A mapped abnormality should not automatically become an ablation target if it cannot be reproduced or if the anticipated risk outweighs the likely clinical gain.

In Australia, this balance is relevant across both public and private electrophysiology services in cities such as Sydney, Melbourne, Brisbane and Perth. Access to high-density mapping platforms can vary between hospitals, and patients from regional Queensland or Western Australia may need to travel substantial distances for complex ablation and follow-up. A technically sophisticated strategy must therefore be weighed against procedural duration, repeat intervention, travel burden and local expertise.

Patient selection and the Australian setting

Biatrial mapping is most likely to provide useful information in carefully selected patients with persistent or long-standing persistent AF, previous ablation failure, atypical atrial tachycardia or evidence of extensive atrial disease. It may be less helpful when AF is driven mainly by untreated risk factors, severe chamber enlargement or a diffuse substrate that offers no discrete target. Optimising blood pressure, weight, sleep apnoea, alcohol intake and heart failure treatment remains essential before interpreting a complex map.

Australian clinical practice also operates within specific regulatory and funding conditions. Mapping catheters and navigation technologies must meet Therapeutic Goods Administration requirements, while local hospital credentialing and procurement decisions influence which systems are available. Research involving patient data or experimental mapping workflows requires review through institutional Human Research Ethics Committees, with privacy obligations shaped by the Privacy Act 1988 and relevant state requirements.

Medicare arrangements do not eliminate the practical costs of travel, time away from work and repeated imaging or procedures. Telehealth can support follow-up for patients living outside metropolitan centres, although rhythm assessment, device interrogation and management of anticoagulation still require appropriate clinical infrastructure. These realities reinforce the value of selecting patients carefully and communicating the expected benefits and uncertainties of driver-guided ablation.

Patient factors should also influence the interpretation of atrial substrate. A person with inflammatory disease, previous cardiac surgery, congenital heart disease or Chagas disease may have a different distribution of scar and conduction abnormalities from a patient with hypertension-related atrial remodelling. The Journal of Arrhythmia’s discussion of Chagas pacing considerations illustrates why disease-specific electrophysiology cannot always be reduced to a standard ablation pathway.

What future studies need to establish

The central research question is whether biatrial mapping improves patient outcomes rather than simply producing more detailed visualisations. Prospective studies should compare mapping-guided treatment with standard ablation while reporting arrhythmia-free survival, quality of life, repeat procedures, atrial function, stroke risk and complications. Consistent definitions of a driver are needed so that results from different mapping platforms can be meaningfully compared.

Future trials may combine electroanatomical data with late gadolinium enhancement magnetic resonance imaging, artificial intelligence, autonomic markers and molecular indicators of fibrosis. Machine-learning methods could help distinguish reproducible driver patterns from signal artefact, but algorithmic outputs will require external validation and transparent reporting. A predictive model should support clinical judgement rather than obscure the uncertainty inherent in mapping a dynamically changing rhythm.

Multicentre collaboration will be particularly important. Differences in catheter design, mapping density, annotation software and operator technique can alter the apparent distribution of drivers. Shared protocols for acquisition, segmentation and follow-up would improve reproducibility. Australian centres could contribute valuable real-world data because they manage diverse populations across metropolitan, regional and remote settings, with meaningful variation in access to specialist care.

The most useful endpoint may eventually be a personalised treatment pathway. Some patients may benefit from pulmonary vein isolation alone, while others may require targeted treatment of a reproducible biatrial circuit or focal trigger. Others may gain more from risk-factor modification, rate control or device-based management than from escalating ablation. Biatrial mapping has the greatest promise when it helps make that distinction with greater confidence.

Clinicians, researchers and trainees can follow emerging evidence through the Journal of Arrhythmia and contribute to the continuing discussion through original research, reviews and clinically grounded reports. For manuscript queries, educational collaboration or publication-related matters, the editorial contact page offers a direct route to the journal team.