Left bundle branch pacing after Surgical septal myectomy: feasibility, electrical performance, and early outcomes
F Nascimento Ferreira, S Jacinto, M Figueiredo, C Oliveira, H Santos, G Portugal, B Valente, P Lousinha, P Osorio, P Silva Cunha, R Cruz Ferreira, M OliveiraAbstract
Background
Surgical septal myectomy (SSM) involves targeted septal reduction and is indicated to prevent secondary left ventricular outflow tract (LVOT) obstruction following correction of aortic stenosis. However, it is frequently associated with conduction disturbances, with permanent pacemaker implantation required in approximately 9–10% of cases. Left bundle branch pacing (LBBP) has emerged as a physiologic pacing alternative that minimizes the desynchrony associated with conventional right ventricular pacing. Post-myectomy septal fibrosis, left septal resection and anatomical remodelling may pose additional technical challenges, influence capture thresholds and may compromise conduction system capture.
Objective
To evaluate the feasibility, acute electrical performance, and early outcomes of LBBP in patients with prior SSP.
Methods
A pilot study was conducted including consecutive patients who underwent LBBP following SSP at a tertiary referral centre. Baseline demographic and echocardiographic characteristics were recorded, along with procedural variables. Electrical performance parameters were assessed at implantation and first device interrogation. Electrocardiographic measurements, including paced QRS duration, V6 R-wave peak time (RWPT), and interpeak V6–V1 interval, were analysed to confirm left bundle recruitment.
Results
Four patients (median age 78 years, 50% female) underwent LBBP following SSP, three for bradyarrhythmia and one for cardiac resynchronization. All implantations were performed via ultrasound guided axillary approach using a stylet-driven lead, achieving selective or non-selective LBB capture (LBBP in 3; LPFP in 1). The median time from surgery to implantation was 4 days, except for one late case (3812 days post-myectomy). At implantation, mean pacing threshold in unipolar mode was 1.0 ± 0.5 V, sensing amplitude in bipolar mode 6.3 ± 1.9 mV, and impedance 614 ± 240 Ω. QRS duration decreased from 148 ± 19 ms@0,4ms to 108 ± 14 ms@0,4ms (Δ = −40 ms), with mean V6 RWPT of 78 ± 6 ms and interpeak V6–V1 interval of 40 ± 12 ms, consistent with effective left bundle capture. At first interrogation, all patients maintained stable thresholds and impedance, without lead dislodgment or capture loss.
Conclusion
LBBP after Surgical septal myectomy appears to be feasible, safe and associated with physiological ventricular activation and stable early electrical parameters. This strategy may represent an effective pacing approach in patients with conduction disturbances following septal myectomy, though larger series are warranted to confirm long-term outcomes and optimal procedural techniques.