Durability of left bundle branch area pacing.

Background: Left bundle branch area pacing (LBBAP) is a form of conduction system pacing. Long-term data on the safety and performance of LBBAP 1 year postdevice implantation has not been well described.
Methods and Results: Sixty-five patients (49% females) who received LBBAP for bradycardia indications using the SelectSecure 3830 lead (Medtronic) were retrospectively evaluated. Clinical variables were examined. Lead parameters were obtained at implant and during regular follow-up. Mean age of patients was 75.7 ± 10.1 years with left ventricular ejection fraction 59.8 ± 10.4%. Indications for pacing were atrioventricular block 55%, sinus node dysfunction 19%, tachy-brady syndrome 15%, atrioventricular node ablation 8%, and bail out cardiac resynchronization therapy 3%. Mean baseline QRS measured 120 ± 38 ms, paced QRS duration was 138 ± 22ms. Paced QRS narrowed by 24 ms in those with pre-existing left bundle branch block (BBB), increased by 1 ms in those with pre-existing right BBB, and increased by 42 ms in those with no BBB. LBBAP threshold at implant was 0.521 ± 0.153 V at 0.4 ms, and increased to 0.654 ± 0.186 V at 3 months (+26%), 0.707 ± 0.186 V at 6 months (+36%), and 0.772 ± 0.220 V at 12 months (+48%). Patients with left BBB showed the maximum benefit with QRS narrowing 24 ms. Pacing impedance remained unchanged with no procedure-related complications.
Conclusion: LBBAP is a durable form of conduction system pacing with pacing thresholds remaining relatively stable over 12 months post device implantation. Patients with left BBB display the narrowest paced QRS.
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