Safety and performance of a novel ICD lead for left bundle branch area pacing: Results from the ASCEND CSP trial

Use of implantable cardioverter defibrillator (ICD) leads for left bundle branch area pacing (LBBAP) has relied on adaptation of conventional leads not designed for conduction system pacing (CSP).

This study aimed to evaluate the safety and effectiveness of a purpose-built CSP ICD lead designed for implantation within the LBBA.

The ASCEND CSP Investigational Device Exemption (IDE) trial is a prospective, multicenter, global, single arm, pivotal trial evaluating the UltiSynq CSP ICD lead (Model LDA1122Q) in patients undergoing de novo ICD or cardiac resynchronization therapy defibrillator (CRT-D) implantation. The primary safety end point was freedom from lead-related serious adverse device effects through 3 months, compared with a pre-specified performance goal of 88%. The primary effectiveness end point was the 3-month composite success rate of acceptable pacing capture threshold and R-wave sensing amplitude, with a performance goal of 80%. Defibrillation testing success was assessed in a pre-specified cohort.

Among 205 implant attempts, 202 patients (98.5%), had successful lead implantation, with LBBAP criteria met in 99.0%. Among these, LBBP or likely LBBP capture criteria were met in 86.0%. The 3-month major complication-free rate was 97.5% and the primary effectiveness end point was achieved in 94.6%, exceeding both safety and effectiveness performance goals. Defibrillation testing was successful in 100%, with 92.5% defibrillated with a single 20 J shock. Lead electrical performance remained stable through 3 months.

In this pivotal IDE trial, a dedicated bipolar CSP ICD lead demonstrated high implant success, stable electrical performance, reliable defibrillation efficacy, and favorable short-term safety. Longer-term follow-up is warranted to confirm durability and sustained clinical benefit.