The recent development and market introduction of small diameter implantable defibrillation leads able to deliver left bundle branch area pacing (LBBAP) has opened the possibility of achieving cardiac resynchronization therapy (CRT) using a single- or dual-chamber implantable-cardioverter defibrillator (ICD). This approach may reduce the number of intracardiac leads required and, consequently, has the potential to lower both procedural and long-term complication rates. However, the integration of these leads into currently recommended CRT strategies remains hypothetical. The FORGE CSP registry will prospectively enroll patients with an indication for CRT in whom implantation of a LBBAP ICD lead is attempted.

The FORGE CSP Registry is a prospective, multicentre and nationwide, post-approval registry, including consecutive patients with an indication for CRT and in whom implantation of a LBBAP ICD lead is attempted as a first line strategy.

The primary objective of this registry is to measure the proportion of patients who achieve effective CRT solely through the use of a LBBAP ICD lead (plus right atrial lead if appropriate).

The secondary objectives of this registry are: (1) to assess the feasibility of the LBBAP ICD lead implantation (regarding LBBAP validated electrophysiologic criteria) and the associated learning curve; (2) to evaluate the incidence of implantation of a third lead, namely a left ventricular lead positioned in the coronary sinus, in combination with the LBBAP ICD lead (LOT-CRT); (3) to assess the risk of complications related to the use of the LBBAP ICD lead, including its impact on tricuspid valve function, the risk of lead dislodgement, and other procedure- or device-related complications; (4) to evaluate de cost-effectiveness of CRT using LBBAP ICD lead, compared with conventional CRT; (5) and to compare CRT response in LBBAP ICD lead recipients, versus historical cohort of conventional CRT.

Inclusion Criteria:

• age > 18-year-old
• indication for CRT according to current ESC/EHRA guidelines
• first-line LBBAP ICD lead implantation attempted
• national insurance coverage

Exclusion Criteria:

• pregnancy

Consecutive patients with a validated CRT indication for whom the implantation of a LBBAP ICD lead in attempted as a first-line strategy.