The goal of this prospective non-randomised study is to test the feasibility of leadless conduction system pacing using the WiSE-CRT device in patients with an indication for Cardiac Resynchronisation Therapy.

The main question[s] it aims to answer are:

1. What is the safety profile of leadless conduction system pacing?
2. What is the success rate of leadless conduction system pacing?
3. What are the electrical and haemodynamic effects of leadless conduction system pacing.

Participants will undergo pre-procedural cardiac CT, and post-procedure electro-anatomical mapping and haemodynamic assessments.

Inclusion Criteria:

• Age over 18 years

• Ability to provide informed consent to participate and willing to comply with the clinical investigation plan and follow-up schedule.

• Patients meeting European Society of Cardiology Criteria for Cardiac Resynchronization Therapy (CRT) with Class 1 or 2a recommendation:

  • Dyssynchronous Heart Failure: Left Ventricular Ejection Fraction (LVEF) ≤35%, QRS duration >150ms or >130ms in presence of left bundle branch block (LBBB). Also included here are patients with EF ≤35%, an existing pacing system and an RV pacing burden of >20%.
  • BLOCK HF population: Patients requiring pacing for atrioventricular (AV) block with an LVEF ≤50%
  • AV node ablation (AVNA) population: Patients planned for AVNA with EF ≤50%.

Exclusion Criteria:

• Any contraindication to LV endocardial pacing.

  • LV thrombus
  • Contra-indication to heparin
  • Contra-indication to anti-platelet agents

• Failure of acoustic window screening

• Septal wall thickness <5mm (minimum required wall thickness at any target implant site)

• Myocardial infarction within 40 days prior to enrolment.

• Cardiac surgery or coronary revascularisation procedure within 3 months prior to enrolment or to be scheduled for such procedures within the following 7 months.

• Participation in other studies with active treatment/investigational arm.

• Pregnant or planning to become pregnant in the next 7 months.