Overview
The goal of this clinical trial is to find out which type of specialist pacemaker-known as cardiac resynchronisation therapy (CRT)-works best for people with heart failure and a delay in how the lower chambers of the heart beat together (called electrical dyssynchrony).
The main aims of the study are:
To compare the effects of conventional biventricular pacing (BVP), conduction system pacing (CSP) and left-bundle optimised CRT (LOT-CRT) on heart failure symptoms and heart rhythm problems over six months.
To explore how these pacing methods affect heart muscle strength, electrical activity, and overall heart function.
Participants will:
Attend four hospital visits over a six-month period.
At Visit 1, meet a member of the research team to discuss the study and have screening tests to check eligibility. Participants will also have a smartphone app installed and receive training on how to record their daily heart failure symptoms.
At Visit 2, have a CRT pacemaker implanted. The type of pacemaker will be chosen at random, with a 1 in 3 chance of receiving:
- Biventricular pacing (BVP); the current standard treatment
- Conduction system pacing (CSP)
- LOT-CRT (Left-bundle optimised CRT); a combination of both
At Visit 3 (around 12 weeks after implantation) and Visit 4 (6 months after implantation), take part in routine follow-up assessments to check the pacemaker and heart function.
At Visits 2 and 4, also undergo non-invasive electrical mapping tests, including wearing a specialised vest and having a low-dose CT scan of the chest. These tests help researchers understand how the heart's electrical system responds to different pacing methods.
Eligibility
Inclusion Criteria:
Patients referred/scheduled for a CRT procedure (new implant or upgrade) who have:
- Symptomatic heart failure (NYHA II-IV)
- Reduced ejection fraction (LVEF≤40%)
- Prolonged QRS duration (≥130ms) and left bundle branch block ECG morphology or very prolonged QRS duration (\>150ms) and non-left bundle branch block ECG
- Optimal medical therapy for HF
Exclusion Criteria:
- Unable to provide informed consent
- \<18 years old
- Pregnant patients (with female patients of childbearing age requiring a negative urine BHCG)