Conduction System Pacing in Atrial Fibrillation with Heart Failure

Patients with atrial fibrillation and reduced ejection fraction represent one of the most challenging cohorts in contemporary cardiology, particularly when symptoms progress despite optimal medical therapy. Across Australian tertiary centres such as Royal Adelaide, Westmead and The Royal Melbourne, electrophysiologists are increasingly turning to conduction system pacing as a physiological alternative to traditional biventricular resynchronisation. The procedure engages the patient's native His-Purkinje network, restoring a more coordinated ventricular activation pattern and offering benefits that align well with cardiac resynchronisation therapy while preserving atrioventricular synchrony where sinus rhythm persists.

The National Heart Foundation of Australia reports that roughly one in twenty adults live with atrial fibrillation, and heart failure with reduced ejection fraction coexists in a substantial proportion. As device technology matures and operator experience deepens, conduction system pacing is moving from an experimental niche to a mainstream consideration in the multidisciplinary heart failure clinic. Trainees on the CSANZ fellowship track now learn both His-bundle and left bundle branch area pacing as part of their core curriculum, reflecting how rapidly this field has evolved.

The Physiological Rationale for Engaging the Native Conduction System

Electrical activation through the His-Purkinje system produces a rapid, near-synchronous biventricular contraction that matches the physiological design of the heart. Conventional right ventricular apical pacing distorts this pattern, generating dyssynchronous contraction that can worsen left ventricular function over time, particularly in patients already vulnerable because of atrial fibrillation and reduced ejection fraction. Engaging the conduction system directly preserves a more physiological wavefront and limits the pro-arrhythmic substrate created by non-physiological pacing sites.

For patients in atrial fibrillation, the appeal extends beyond ventricular synchrony. When AV node ablation is required for rate control, conduction system pacing provides a coordinated escape rhythm that minimises the risk of wide-QRS dyssynchrony, an important consideration in those who would otherwise depend on chronic right ventricular pacing. Studies cited in the Journal of Arrhythmia suggest that left bundle branch area pacing in particular can deliver resynchronisation comparable to coronary sinus lead placement, while avoiding many of the anatomical constraints that complicate left-sided implantation in patients with dilated cardiomyopathy.

Selecting Suitable Candidates Among Patients with Atrial Fibrillation and Heart Failure

Patient selection begins with careful mapping of the arrhythmia and the structural substrate. Patients with long-standing persistent atrial fibrillation, severely dilated left atria, and high pulmonary pressures require individualised assessment, since the benefit of restoring AV synchrony is limited when sinus rhythm cannot be reliably maintained. Conversely, those with paroxysmal atrial fibrillation, early-stage atrial remodelling, and left ventricular ejection fraction below thirty-five percent often represent strong candidates, especially when QRS duration is modestly prolonged or when the patient is anticipated to require a high burden of ventricular pacing.

Within Australian practice, candidacy decisions are usually made within a heart team that includes an electrophysiologist, a heart failure cardiologist, an imaging specialist and often a cardiac surgeon. Public hospital waitlists at centres such as the Prince Charles Hospital in Brisbane or Fiona Stanley in Perth shape the timing of intervention, and clinicians frequently optimise guideline-directed medical therapy for several months before listing for device implantation. Functional capacity, frailty, and renal function all feed into the final decision, with device choice reflecting a balance between expected symptomatic gain and procedural risk.

Implantation Techniques and Practical Considerations

Achieving successful conduction system capture demands precision. His-bundle pacing requires identifying the His electrogram and placing the lead in a position that captures the bundle directly, often using dedicated sheaths and stylet-driven delivery systems. Left bundle branch area pacing has become the more popular technique in many Australian labs because of its broader safety margin and more achievable capture thresholds, particularly in patients with infranodal conduction disease. Implantation typically involves a transventricular septal approach using a dedicated lumenless lead delivered through a fixed-curve or deflectable sheath.

Fluoroscopy times tend to be longer than for routine dual-chamber implants, and operators rely on a combination of unipolar pacing impedance mapping, intracardiac electrograms, and increasingly on electro-anatomical mapping integration. In teaching hospitals such as Monash Medical Centre, fellows are taught to recognise the characteristic narrow-QRS morphology that confirms left-sided conduction system capture, distinguishing it from mere septal myocardial capture. Procedure times of between seventy and one hundred and twenty minutes are typical, with significant variation based on the underlying conduction disease and atrial remodelling.

Clinical Outcomes Relative to Conventional Resynchronisation

Randomised comparisons and large registry analyses suggest that conduction system pacing produces meaningful improvements in left ventricular ejection fraction, with gains of roughly five to ten absolute percentage points in properly selected patients. QRS narrowing is often more pronounced with His-bundle pacing than with biventricular CRT, while left bundle branch area pacing yields very high response rates across broad patient populations. Hospitalisation rates for heart failure decline, and exercise capacity as measured by cardiopulmonary testing improves, particularly when atrial fibrillation is converted to sinus rhythm or when AV node ablation is added to achieve reliable rate control.

In Australian real-world cohorts followed by groups at the Baker Heart and Diabetes Institute, the benefits have tracked closely with international experience. Mortality outcomes remain favourable when compared with right ventricular pacing, and the risk of pacing-induced cardiomyopathy appears substantially reduced. Local data also indicate that patients with atrial fibrillation and bundle branch block respond particularly well, especially when the block is relatively narrow or when the conduction system lesion can be recruited with a modest increase in pacing output. These findings are reshaping how device clinics frame the conversation with patients referred for resynchronisation.

Managing the Risk of Lead-Related Tricuspid Regurgitation

Tricuspid regurgitation is a recurring concern with any transvenous right-sided lead, and conduction system pacing leads traversing the tricuspid valve can contribute to leaflet impingement or perforation. Careful attention to lead trajectory, deployment height, and final tip position is critical to minimise this risk. Discussions around lead-related tricuspid regurgitation increasingly inform consent processes in Australian device clinics, with operators emphasising techniques that position the lead along the septum rather than the free wall.

Pre-procedural echocardiography, including three-dimensional assessment of tricuspid anatomy, helps identify patients with pre-existing leaflet tethering or annular dilatation. Post-implant surveillance includes routine echocardiography at six to twelve months, with earlier review if there is symptomatic deterioration. In some Australian centres, same-day procedural collaboration with cardiac imaging specialists has become standard, allowing immediate repositioning when a lead appears to interfere with leaflet coaptation. Such forward planning has been associated with lower rates of clinically significant tricuspid regurgitation at twelve-month follow-up in local registries.

Recognising Premature Ventricular Contractions in the Pacing Population

Frequent premature ventricular contractions complicate the assessment of pacing candidates because they can themselves depress left ventricular function and mimic or worsen heart failure. A substantial proportion of patients referred for conduction system pacing in atrial fibrillation are found on pre-procedural monitoring to have a high PVC burden, sometimes exceeding ten percent of total beats. Distinguishing idiopathic ectopy from scar-mediated arrhythmia is essential because management strategies differ substantially. Decisions about idiopathic PVC ablation often involve a separate electrophysiology consultation before committing to a permanent pacing strategy.

In practice, a stepwise pathway has emerged across major Australian EP centres. Initial workup includes twenty-four-hour Holter monitoring or, increasingly, longer-term patch-based recordings that document PVC burden over two weeks. Where the burden is high and the morphology suggests a focal right ventricular outflow tract or fascicular origin, catheter ablation is offered either before or in conjunction with device implantation. When PVCs persist despite successful pacing, repeat ablation may be considered, with several Australian groups now reporting combined procedures in single anaesthetic sessions. This integrated approach reflects the broader movement toward arrhythmia-focussed heart failure management.

Delivering Conduction System Pacing Across the Australian Healthcare System

Access to conduction system pacing is shaped by funding, training and geography in ways that affect both patients and clinicians. Devices are listed on the Medicare Benefits Schedule for approved indications, and private insurers such as Bupa and Medibank generally provide coverage within their chronic disease management frameworks, although out-of-pocket costs vary between metropolitan and regional providers. Device manufacturers must hold Therapeutic Goods Administration certification for the lead systems used, and recent approvals have expanded the range of tools available to Australian implanters.

Regional and rural patients face particular challenges. Long travel distances to specialised centres such as Royal Hobart Hospital or Townsville University Hospital can delay referral and complicate follow-up. The rise of telehealth device clinics, accelerated by pandemic-era reforms, has helped bridge this gap, allowing remote interrogation of devices and asynchronous review of transmitted data. Outreach initiatives between metropolitan training centres and regional hospitals are gradually building local expertise, though workforce constraints remain real. Continued investment in structured training pathways, registry participation through platforms anchored in Australian research, and equitable funding for both implantation and revision procedures will determine how widely conduction system pacing benefits reach the communities most affected by atrial fibrillation and heart failure.

The growing body of evidence supporting conduction system pacing is reshaping expectations for patients living with atrial fibrillation and heart failure. Clinicians and researchers across the country can help define the next phase of this field by submitting their work, sharing procedural experience, and engaging with the global arrhythmia community through the Journal of Arrhythmia. Submissions, themed collections, and educational resources remain open to contributors from every Australian centre, and the journal welcomes original research, reviews, and clinical perspectives that advance the science and practice of physiological pacing.