Mechanisms and Innovations in Cardiac Resynchronisation Therapy

Evaluation of Mechanisms and Innovations in Cardiac Resynchronization Therapy

The aim of this study is to compare the effectiveness of multiple modalities of cardiac resynchronisation therapy using high precision acute electrical and haemodynamic measurements.These modalities include biventricular pacing and conduction system pacing utilising His bundle and left bundle pacing. Conduction system pacing is a more physiological form of pacing. The study hypothesises that this will produce more effective cardiac resynchronisation.

This is a single centre acute electrical/haemodynamic and observational study of a subgroup of patients with heart failure. A total of 60 will be recruited. The acute study involves within patient comparison of biventricular and conduction system pacing using detailed electrical mapping and high precision haemodynamic measurement protocol.

Participants will have permanent conduction system pacing if;

• Baseline left bundle branch block and QRS > 140ms or QRS >150ms and any QRS morphology AND
• Conduction system pacing is successful at reducing QRS duration by 20ms or more with satisfactory pacing parameters.

Participants who receive permanent conduction system pacing will have follow up at 6 weeks, 3 months, 6 months and 12 months. Non-invasive markers including mechanical activation pattern (echocardiography and cardiac MRI) and electrical activation pattern (ultra-high frequency electrocardiography) will be used to identify the characteristics of patients who benefit from conduction system pacing.

Inclusion Criteria:

• Patients referred for conventional CRT
• Severe heart failure (LVEF, a measure of heart pumping, < 35% - severe)
• Prolonged QRS duration (>120ms)
• Adults willing to take part (age > 18 years)
• Able to give consent

Exclusion Criteria:

• Unable to give consent
• Children (age < 18 years)
• Pregnant women