His–Purkinje pacing for patients with left ventricular dysfunction

Conventional right ventricular pacing can produce electrical and mechanical dyssynchrony, particularly when a high proportion of ventricular beats is paced. In patients with impaired left ventricular ejection fraction, that burden may worsen heart failure symptoms, promote adverse remodelling, and increase hospitalisation risk. His–Purkinje system pacing offers a physiological alternative by activating the native conduction network rather than relying on broad myocardial wavefront propagation.

The term includes His bundle pacing (HBP) and left bundle branch area pacing (LBBAP), with the latter increasingly used when selective or stable His capture is difficult. The clinical decision is not simply a choice between two lead positions. It involves the cause of ventricular dysfunction, expected pacing burden, QRS morphology, venous access, device longevity, operator experience, and whether the patient meets criteria for cardiac resynchronisation therapy.

Why ventricular synchrony matters

The His–Purkinje network normally distributes activation rapidly through the ventricles. A right ventricular apical or septal lead bypasses that system and can create a paced QRS with delayed activation of the lateral left ventricular wall. In a patient with a normal ventricle, this may be tolerated for years. In someone with reduced ejection fraction, frequent dyssynchronous activation can add a preventable haemodynamic burden.

Pacing-induced cardiomyopathy is usually considered when left ventricular function declines after substantial right ventricular pacing, although the relationship is influenced by baseline function, paced QRS duration, atrioventricular timing, and myocardial disease. Conduction system pacing may preserve ventricular synchrony and reduce the likelihood of this deterioration. It can also be used as a rescue strategy when a patient with an existing device develops worsening function and a high pacing burden.

The physiological objective differs from simply narrowing the paced QRS. Effective capture should produce consistent ventricular activation, appropriate lead thresholds, and meaningful clinical benefit. Echocardiographic response, symptoms, exercise capacity, and heart failure events remain important alongside electrocardiographic measurements.

His bundle pacing and left bundle branch area pacing

His bundle pacing places the lead at the atrioventricular conduction axis, aiming to capture the native His bundle directly. Selective HBP produces a QRS resembling intrinsic conduction, while non-selective capture activates the His bundle and nearby myocardium. This approach can correct some forms of bundle branch block, although correction is less predictable in extensive distal conduction disease.

LBBAP advances a specialised lead through the interventricular septum to capture the left bundle branch region or nearby fascicles. It generally offers a larger target, lower and more stable thresholds in many series, and reliable ventricular sensing. The technique may produce a right bundle branch block pattern on the surface ECG, so lead position and electrical criteria should be interpreted together rather than using morphology alone.

Neither method is automatically superior for every patient. HBP may provide the most anatomically faithful activation when capture is stable, whereas LBBAP can be attractive in patients requiring substantial pacing or when His thresholds are high. Long-term comparative data in patients with significant left ventricular dysfunction are still developing, especially for hard outcomes such as mortality and recurrent heart failure admission.

Patients most likely to benefit

A patient with a reduced ejection fraction who is expected to require frequent ventricular pacing deserves an early discussion of physiological pacing. This includes individuals with advanced atrioventricular block, slow atrial fibrillation requiring pacing, and anticipated atrioventricular node ablation. Patients with an existing pacemaker, a high right ventricular pacing percentage, a widening paced QRS, and a subsequent fall in ejection fraction may also be candidates for an upgrade.

Cardiac resynchronisation therapy with biventricular pacing remains an established treatment for selected patients with heart failure, reduced ejection fraction, sinus rhythm, and a broad QRS, especially typical left bundle branch block. Conduction system pacing can be considered when coronary sinus lead placement is unsuccessful, when venous anatomy is challenging, or when a more physiological activation pattern is desired. It may also serve as an alternative in carefully selected patients who do not respond to conventional CRT.

Assessment should include the original cause of cardiomyopathy, scar distribution, valve disease, atrial rhythm, renal function, frailty, and competing illness. A narrow native QRS does not exclude benefit when a high pacing burden is expected, but it does make the indication more dependent on the pacing requirement and the likelihood of ventricular dysfunction.

Planning the implant

Pre-procedure planning starts with a 12-lead ECG, echocardiography, device interrogation when applicable, and a clear estimate of anticipated ventricular pacing. Coronary angiography or cardiac magnetic resonance may be relevant when ischaemic disease or scar will influence the expected response. The team should document the intended pacing strategy, backup options, and criteria for changing from HBP to LBBAP or to a coronary sinus lead.

Implantation requires careful fluoroscopic and electrocardiographic assessment. For HBP, the operator identifies the His potential and monitors paced QRS changes, capture thresholds, and evidence of bundle branch correction. For LBBAP, lead depth, paced morphology, stimulus-to-ventricular activation intervals, and signs of left septal or left bundle capture are assessed. Contrast venography is not always necessary, but venous access planning matters in upgrades and patients with prior devices.

A practical advantage of a defined fallback plan is that procedure time can be controlled. Prolonged attempts at one target may increase radiation exposure and lead manipulation without improving the final result. In patients with severe heart failure or haemodynamic instability, the procedural strategy should be proportionate to the expected clinical gain.

Benefits and limitations in left ventricular dysfunction

Early observational studies and prospective cohorts suggest that conduction system pacing can narrow the QRS, improve ejection fraction, reduce ventricular volumes, and improve New York Heart Association functional class in selected patients. The most convincing signal is often seen in pacing-induced cardiomyopathy, where removal of an adverse right ventricular activation pattern may allow reverse remodelling.

The evidence base has important limitations. Many studies are single-centre, include experienced operators, and use different definitions of successful capture and response. Follow-up is often shorter than the lifespan of a pacemaker system. Randomised comparisons with biventricular CRT, especially in patients with ischaemic scar, advanced heart failure, or atrial fibrillation, remain necessary.

There are also technical risks. HBP may have rising thresholds, intermittent loss of capture, or difficulty maintaining a safety margin. LBBAP carries risks of septal perforation, lead dislodgement, conduction injury, and uncertain long-term extraction considerations. A device that appears physiologically attractive at implant still requires durable sensing, capture, and lead integrity.

Follow-up, programming, and safety

Follow-up should confirm the pacing percentage, capture threshold, sensing, battery estimate, QRS response, and left ventricular function. HBP systems may require a higher programmed output or a backup ventricular lead in selected patients who are pacing-dependent. LBBAP thresholds are often favourable, but stability must be demonstrated over time rather than assumed from the implant measurement.

Programming should reflect the patient’s atrial rhythm, conduction, chronotropic needs, and heart failure treatment. Unnecessary ventricular pacing should be avoided when intrinsic conduction is reliable, while patients dependent on pacing need adequate output and protection from abrupt loss of capture. Remote monitoring can identify threshold changes, lead impedance abnormalities, arrhythmia burden, and battery depletion between clinic visits.

Lead surveillance is particularly relevant for younger patients who may undergo multiple generator changes. Device teams can use published lead integrity guidance to reinforce broader principles of alarm interpretation, stored electrogram review, and timely escalation when electrical measurements become abnormal. The specific lead system differs, but the need for structured monitoring is universal.

Delivering care in Australia

Australian practice is shaped by a mixed public and private health system, Medicare-funded care, local hospital capability, and referral pathways into high-volume electrophysiology centres. A patient from regional New South Wales may need to travel to Sydney for implantation and return to a local cardiology service for surveillance. In Western Australia, long distances can make remote monitoring and coordinated shared care especially valuable.

The local device market also affects planning. Lead and generator availability, procurement arrangements, MRI-conditional requirements, and manufacturer support can vary between metropolitan and regional hospitals. Teams should confirm stock, compatible programmers, extraction expertise, and access to urgent review before selecting a system. These practical details can influence the safety of an otherwise sound physiological pacing plan.

Australian centres commonly use multidisciplinary discussion involving electrophysiologists, heart failure specialists, imaging cardiologists, cardiac physiologists, nurses, and device technicians. Clear communication is important when a patient moves between public outpatient clinics, private rooms, and rural services. Education should cover wound care, driving restrictions, remote-monitoring alerts, travel, and when to seek urgent help, using language appropriate to the patient and family.

The country’s large geography makes telehealth useful, although it cannot replace an examination when infection, lead displacement, syncope, or heart failure decompensation is suspected. Local protocols should also account for Aboriginal and Torres Strait Islander patients, culturally safe communication, transport barriers, and the practical consequences of repeated metropolitan appointments.

Building the evidence base

Research priorities include randomised trials comparing HBP, LBBAP, and biventricular CRT; standardised definitions of successful conduction system capture; and longer follow-up for lead performance, extraction, infection, battery longevity, and mortality. Subgroup analysis is needed for women, older adults, patients with atrial fibrillation, advanced kidney disease, infiltrative cardiomyopathy, and extensive myocardial scar.

Registries can help describe real-world outcomes across hospitals with different levels of experience. Important endpoints should include change in ejection fraction, heart failure admission, quality of life, appropriate defibrillator therapy, procedural complications, reintervention, and cost. Health-economic evaluation is particularly relevant in Australia, where travel distance and repeated specialist visits can materially affect the overall burden of care.

Clinicians and trainees can follow current evidence through the journal’s themed collections, while investigators can review recent arrhythmia research when shaping protocols or identifying unanswered questions. Transparent reporting of failed implants, threshold changes, and crossover strategies will make future guidance more useful than success-only series.

His–Purkinje system pacing is an important part of the evolving approach to ventricular dysfunction and pacing-related dyssynchrony. Its best use depends on patient selection, technical discipline, close follow-up, and honest comparison with established CRT options. Electrophysiology services can strengthen care by developing local pathways, auditing outcomes, and sharing experience across metropolitan, regional, and rural networks.