Cardiac Resynchronisation Therapy In Patients With Heart Failure: Mechanistic Insights From Cardiac MRI And Electroanatomical Mapping

Cardiac Resynchronisation Therapy In Patients With Heart Failure: Mechanistic Insights From Cardiac MRI And Electroanatomical Mapping

Cardiac Resynchronisation Therapy (CRT) is a specialist pacemaker procedure that aims to improve the efficiency of the heartbeat. This treatment is used routinely in patients with heart failure and a delay in electrical conduction across the heart seen on the surface ECG (heart tracing). The investigators aim to assess acute response to CRT and compare different methods of delivering CRT using hemodynamic data from invasive dP/dTmax and electroanatomical data from either invasive mapping or non-invasive body surface mapping.

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study.
• Male or Female, aged 18 years or above.
• Either 1) has CRT system in situ or 2) has a planned CRT system implant or 3) has a planned upgrade to CRT from a standard pacemaker
• NYHA grade II-IV heart failure
• LVEF<35%
• Intrinsic QRS duration >120ms
• On optimum medical therapy for heart failure
• Female participants of child bearing potential must be willing to ensure that they or their partner use effective contraception during the study and for 3 months thereafter
• Able (in the Investigators opinion) and willing to comply with all study requirements.
• Willing to allow his or her General Practitioner and consultant, if appropriate, to be notified of participation in the study.

Exclusion Criteria:

• Female participants who is pregnant, lactating or planning pregnancy during the course of the study.
• Scheduled elective surgery or other procedures requiring general anaesthesia during the study.
• Participant who is terminally ill or is inappropriate for placebo medication
• Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study.
• Rate uncontrolled atrial fibrillation precluding a cMR
• Significant peripheral vascular disease precluding an EP study
• A contraindication to anticoagulation
• A prosthetic aortic or tricuspid valve
• Significant Aortic valve disease
• Known LV thrombus
• Insufficient capacity to consent to the study