Repositioning and extraction of stylet-driven pacing leads with extendable helix used for left bundle branch area pacing

Conventional stylet-driven leads with extendable helix can be implanted successfully for left bundle branch area pacing (LBBAP) with a low acute complication rate. We report two cases in which lead repositioning after a first unsuccessful attempt to LBBAP was associated with fracture of the helix rotating mechanism and failure to fully extract the pacing lead.     

Clinical use conditions of lead deployment and simulated lead fracture rate in left bundle branch area pacing

Introduction

Left bundle branch area pacing (LBBAP) is achieved by advancing the lead tip deep in the septum. Most LBBAP implants are performed using the Medtronic SelectSecure™ MRI SecureScan™ Model 3830 featuring a unique 4 Fr fixed helix lumenless design. Details of lead use conditions and long-term reliability have not been reported. This study was designed to quantify the mechanical use conditions for the 3830 lead during and after LBBAP implant, and to evaluate reliability using bench testing and simulation.

Methods

Fifty bradycardia patients with implantation of the 3830 lead for LBBAP were enrolled. Use conditions of lead deployment at implantation were collected and computed tomography (CT) scans were performed at 3-month follow-up. Curvature amplitude along the pacing lead was determined with CT images. Fatigue bending was performed using accelerated testing in a more severe environment than routine clinical use conditions. Conductor fracture rate in a simulated patient population was estimated based on clinical use conditions and fatigue test results.

Results

The number of attempts to place the 3830 lead for LBBAP was 2.1 ± 1.3 (range: 1–7) with 13 ± 6 lead rotations at the final attempt. Extreme implant conditions were simulated in bench testing with 5 applications of 20 turns followed by up to 400 million bending cycles. Reliability modeling predicted a 10-year fracture rate of 0.02%.

Conclusions

LBBAP implants require more lead rotations than standard pacing implants and result in unique lead bending. Application of simulated LBBAP use conditions to the 3830 lead in an accelerated in-vitro model does not produce excess conductor fractures. IMAGE-LBBP Study ID of ClinicalTrial.GOV: NCT04119323.     

Late dislodgement of left bundle branch pacing lead and successful extraction

A 61-years-old male underwent left bundle branch pacing for nonischemic dilated cardiomyopathy with recurrent heart failure. Left bundle branch pacing (LBBP) resulted in reduction in QRS duration along with improvement in left ventricular ejection fraction (LVEF) to 64% during follow-up. Two years after implantation he had recurrence of symptoms along with decline in LVEF to 51%. Late lead dislodgement was diagnosed and re-do LBBP was planned. The lead was extracted en-masse without complication and a new 3830 lead was positioned deep inside the proximal septum to capture the left bundle. Postprocedure echocardiography showed no ventricular septal defect or damage to tricuspid leaflet.     

Cardiac troponin release following left bundle branch pacing

Left bundle branch pacing (LBBP) has emerged as an alternative to His bundle pacing (HBP) to achieve physiologic ventricular stimulation. The extent of myocardial injury during permanent LBBP implantation is currently not known. The aim of the study was to prospectively assess the extent of myocardial injury during LBBP implantation. Cardiac troponin (cTn) levels were measured at baseline and 6–12 h following permanent LBBP. The number of attempts to achieve LBBP was documented. Troponin levels were measured in a control population undergoing other electrophysiology procedures including HBP, other devices involving right ventricular (RV) pacing, radiofrequency ablation for atrial fibrillation (AF) and supraventricular tachycardia (SVT). Significant elevation of troponin (SET) was defined as threefold increase above the upper reference limit (URL) for cTn. Between December 2019 and April 2020, 204 were prospectively enrolled: LBBP in 98 and Control group 106 (SVT, 55; AF, 20; HBP, 17; other devices, 14). SET (>3× URL) was seen in 49.4% of patients in the LBBP group compared to 58.4% in the control group (p = .23). Peak troponin levels were greater in the control group compared to the LBBP group (230.3 ± 320.1 vs. 87.4 ± 71.3 pg/ml; p = .0001). Compared to LBBP (49.4%), SET was observed less frequently following HBP (17.5%; p = .01), and other device implantation (29%; p = .15). Patients requiring >2 attempts (n = 33) had significantly higher incidence of SET compared to <2 attempts (n = 56; 66.7% vs. 39.3%; p = .01). LBBP implantation is associated with myocardial injury. Asymptomatic troponin release following LBBP is less than or comparable to other interventional electrophysiology procedures.     

Remarkable response to cardiac resynchronization therapy via left bundle branch pacing in patients with true left bundle branch block

BackgroundLeft bundle branch pacing (LBBP) has been suggested as an alternative means to deliver cardiac resynchronization therapy (CRT).HypothesisLBBP may deliver resynchronization therapy along with an advantage over traditional biventricular (BiV) pacing in clinical outcomes.MethodsHeart failure patients who presented LBBB morphology according to Strauss''s criteria and received successful CRT procedure were enrolled in the present study. Propensity score matching was applied to match patients into LBBP‐CRT group and BiV‐CRT group. Then, the electrographic data, the echocardiographic data and New York heart association (NYHA) class were compared between the groups.ResultsTwenty‐one patients with successful LBBP procedure and another 21 matched patients with successful BiV‐CRT procedure were finally enrolled in the study. The QRS duration (QRSd) was narrowed from 167.7 ± 14.9 ms to 111.7 ± 12.3 ms (P < .0001) in the LBBP‐CRT group and from 163.6 ± 13.8 ms to 130.1 ± 14.0 ms (P < .0001) in the BiV‐CRT group. A trend toward better left ventricular ejection fraction (LVEF) was recorded in the LBBP‐CRT group (50.9 ± 10.7% vs 44.4 ± 13.3%, P = .12) compared to that in the BiV‐CRT group at the 6‐month follow‐up. A trend toward better echocardiographic response was documented in patients receiving LBBP‐CRT procedure (90.5% vs 80.9%, P = .43) and more super CRT response was documented in the LBBP‐CRT group (80.9% vs 57.1%, P = .09) compared to that in the BiV‐CRT group.ConclusionsLBBP‐CRT can dramatically improve the electrical synchrony in heart failure patients with LBBB. Meanwhile, compared with the traditional BiV‐CRT, it has a tendency to significantly improve LVEF and enhance the NYHA cardiac function scores.