His Bundle Pacing for Atrial Fibrillation and Slow Ventricular Rates

Atrial fibrillation with a slow ventricular response creates a distinctive pacing problem. The atria are electrically disorganised, yet the ventricles may beat too slowly because of atrioventricular conduction disease, rate-limiting medicines, advanced age-related fibrosis, or intentional AV node ablation. A pacemaker can prevent bradycardia, but the choice of ventricular pacing site may influence long-term ventricular function, symptoms, and heart failure risk.

His bundle pacing (HBP) directly stimulates the native His–Purkinje system, offering a more physiological alternative to conventional right ventricular pacing in selected patients. Its role is particularly relevant when a person with persistent or permanent atrial fibrillation is likely to require a high percentage of ventricular pacing. Careful assessment remains essential because atrial sensing and synchrony are limited in AF, while lead thresholds, anatomy, operator experience, and follow-up resources shape the practical decision.

Why Slow Ventricular Response Matters

In AF, a slow ventricular rate may reflect intrinsic AV node disease, the effect of beta-blockers or digoxin, or a combination of both. Some patients have intermittent pauses, while others present with persistent bradycardia, exercise intolerance, presyncope, or worsening fatigue. Medication review is important, but stopping a useful rate-control drug does not always restore adequate conduction. When bradycardia is clinically significant, permanent pacing may be required.

The pacing objective is usually straightforward: maintain a reliable ventricular rate and reduce symptoms. The longer-term question is how the ventricle will be activated. Conventional right ventricular apical pacing can produce electrical and mechanical dyssynchrony, especially when pacing is frequent. Septal pacing may reduce this effect in some cases, but it does not consistently reproduce normal conduction. HBP seeks to preserve a narrower QRS and coordinated ventricular contraction by engaging the His bundle below or around the site of conduction disease.

Selecting Patients for His Bundle Pacing

HBP is most attractive when substantial ventricular pacing is expected and left ventricular function should be protected. This includes patients with permanent AF and advanced AV block, those undergoing AV node ablation for uncontrolled rapid AF, and individuals with a high pacing burden who have borderline or reduced ejection fraction. It may also be considered when a patient has a relatively narrow intrinsic QRS and a reasonable chance of His capture.

The indication should be separated from the technical feasibility of the procedure. A baseline electrocardiogram, echocardiogram, medication history, renal assessment, and review of AF duration help establish the clinical context. In patients with intermittent AF or a realistic possibility of restoring sinus rhythm, atrial pacing needs may change over time. In permanent AF, a single-chamber ventricular system is often sufficient, although the final configuration depends on the rhythm history and anticipated management.

Patients with established bundle branch disease, extensive septal scar, or distal conduction-system pathology may have a lower likelihood of selective His capture. Left bundle branch area pacing can be a useful alternative when HBP thresholds are high or capture is unreliable. The decision should be individualised rather than driven by the label of “physiological pacing” alone.

Procedural Technique And Device Programming

The His bundle is identified using a delivery sheath and electrogram-guided mapping, with fluoroscopic and electrical landmarks supporting lead placement. Testing should distinguish His capture from adjacent myocardial capture and document the paced QRS, capture threshold, sensing characteristics, and output required for reliable conduction-system recruitment. In AF, atrial electrograms are less useful for synchrony, so ventricular timing and protection from pauses become central programming goals.

HBP can involve a higher acute or chronic capture threshold than standard right ventricular pacing. Threshold rise, lead dislodgement, and difficulty obtaining stable sensing are important considerations. Some operators implant a backup right ventricular lead in patients who are pacemaker-dependent or have a high risk of lead failure. Battery longevity should be discussed because higher output settings can increase generator depletion and future replacement procedures.

Programming often uses a lower rate appropriate to symptoms, age, autonomic state, and comorbidity, with rate-response functions considered when chronotropic competence is limited. A patient with permanent AF does not require atrial tracking, while a patient with paroxysmal AF may need a different strategy. Device checks should review capture at programmed output, QRS morphology, ventricular lead impedance, episodes of high-rate activity, and any progression of conduction disease.

Evidence, Outcomes, And Limitations

Observational studies and growing comparative evidence suggest that conduction-system pacing can narrow the paced QRS and reduce the risk of pacing-induced cardiomyopathy compared with a high burden of right ventricular pacing. In patients undergoing AV node ablation, HBP may preserve left ventricular function and improve functional status, particularly when baseline ventricular function is impaired. However, the strength of evidence varies, and many studies are non-randomised or include mixed rhythm populations.

The benefit should therefore be framed as a balance between physiological activation and procedural complexity. HBP may be difficult in patients with a large tricuspid annulus, challenging venous anatomy, extensive conduction disease, or previous cardiac procedures. Follow-up can require more specialised interpretation than routine pacemaker care. Left bundle branch area pacing has gained attention because it may provide stable low thresholds and a practical route to conduction-system recruitment, although it has its own risks, including septal perforation and lead-related complications.

Clinical outcomes should include symptoms, ventricular function, hospitalisation, lead performance, and quality of life rather than QRS duration alone. A patient who feels well with stable conventional pacing may not gain enough from a technically demanding revision. Conversely, a patient expected to be paced continuously may benefit from early consideration of a physiologic strategy.

Infection Prevention And Long-Term Care

Device infection is uncommon but serious, particularly when extraction is required. Before implantation, clinicians should address active infection, skin integrity, diabetes control, anticoagulation planning, and the necessity of every component in the system. A smaller system may reduce hardware exposure, but the choice must still provide reliable pacing for the patient’s clinical situation. The Journal of Arrhythmia’s discussion of device infection prevention provides useful context for implantation, prevention, and extraction decisions.

Long-term surveillance is especially important for people with persistent AF because symptoms may be attributed to the arrhythmia when the real problem is loss of capture, battery depletion, or progressive heart failure. Device clinics should coordinate electrocardiography and echocardiography with remote monitoring where available. In Australia, access to specialist follow-up can differ between metropolitan hospitals in Sydney or Melbourne and regional or remote services, making clear escalation pathways particularly important.

Patients should receive practical advice about wound care, fever or pocket redness, syncope, and electromagnetic interference. Everyday realities such as long-distance driving between regional towns, outdoor work, and travel across large distances can affect appointment planning and emergency access. These factors are part of safe device care, not administrative details.

The Australian Clinical Context

In Australia, implantation may occur through a public hospital, a private cardiac service, or a shared-care arrangement. The Therapeutic Goods Administration regulates cardiac implantable electronic devices, while Medicare arrangements influence consultations, investigations, and follow-up. Device selection is also shaped by local procurement, manufacturer support, operator training, and whether a hospital can provide timely conduction-system pacing and extraction services.

The Australian market is concentrated around major electrophysiology centres in cities such as Sydney, Melbourne, Brisbane, Perth, and Adelaide, while patients from rural and remote communities may travel substantial distances for implantation or revision. Telehealth and remote device monitoring can reduce some travel, but they do not replace in-person wound assessment, threshold testing, or echocardiography. Shared protocols between tertiary centres and local cardiology teams can improve continuity after discharge.

The wider rhythm history also deserves attention. Some patients with AF and slow rates have tachy-brady syndrome, autonomic influences, or an incorrectly attributed athletic low resting rate. Guidance on sinus node assessment is relevant when the diagnosis is uncertain, although athletic sinus bradycardia is different from persistent AF with inadequate ventricular conduction. Decisions should reflect Australian clinical governance, informed consent requirements, anticoagulation practice, and the patient’s access to follow-up rather than relying on a single electrocardiographic finding.

For clinicians managing AF with bradycardia, HBP is best approached as part of a broader pacing strategy: define the indication, estimate the expected pacing burden, assess ventricular function, compare conduction-system options, and plan lifelong surveillance. Journal of Arrhythmia offers a valuable setting for reviewing emerging evidence, technical reports, clinical guidelines, and regional practice perspectives. Read the related resources, discuss suitable cases within the multidisciplinary electrophysiology team, and apply a documented, patient-centred approach to device selection and follow-up.