Evaluation of first-phase ejection fraction to guide cardiac resynchronisation therapy-a randomised controlled trial
Cardiac resynchronisation therapy, heart failure
People with heart failure who are referred for a special pacemaker treatment called cardiac resynchronisation therapy (CRT) will be invited to take part. Everyone will have their usual heart assessments, including heart scans, blood tests and routine check-ups, before and after the pacemaker is fitted. Six months after their CRT implant, the doctors will check how well their heart has responded. If the heart has not improved as expected, participants will be randomly allocated (using a secure online system) into one of two groups: Standard Care Group: The pacemaker settings will be adjusted in the usual way, based on standard heart scan measurements that look at how well the heart fills with blood. EF1-Guided Group: The pacemaker settings will be adjusted using a new heart scan measurement called EF1, which looks at how strongly the heart pumps at the very start of each heartbeat. After these adjustments, all participants will continue with their usual care and have follow-up visits at 12 months and again at 36 months to see if their heart function and symptoms have improved.
Current key inclusion criteria as of 22/06/2026: 1. Age ≥18 years 2. Good understanding of English 3. Receiving optimal medical therapy for heart failure 4. Fulfilling current guideline criteria for cardiac resynchronisation therapy (CRT), including CRT-P, CRT-D, and conduction system pacing (NYHA Class II–IV, LVEF ≤35%, and QRS duration >130 ms) _____ Previous key inclusion criteria: 1. Age over 18 years 2. Strong understanding of English 3. On optimal medical therapy for heart failure 4. Fulfilling standard consensuses guidelines (NYHA class II-IV, EF ≤35% and QRS duration>130ms) for CRT ( including conduction pacing system)
Current key exclusion criteria as of 22/06/2026: 1. Co-morbidity expected to reduce life expectancy to less than 6 months 2. Major cardiovascular event within the previous 6 weeks 3. More than mild aortic stenosis 4. Continuous or intermittent infusion therapy for heart failure 5. Suboptimal ultrasound acoustic window 6. Inability to provide informed consent 7. Current participation in another interventional study that, in the opinion of the Chief Investigator, may interfere with the objectives or assessments of this study _____ Previous key exclusion criteria: 1. Co-morbidity expected to reduce life expectancy to less than 6 months 2. Major cardiovascular event in the previous 6 weeks 3. More than mild aortic stenosis 4. Continuous or intermittent infusion therapy for heart failure 5. Suboptimal ultrasound acoustic window 6. Inability to give informed consent 7. Current participant in other interventional studies