An interventional study of Pacemaker - Physiological pacing and Pacemaker - Right Ventricular pacing in Bradycardia, Pacing and Right Ventricular Pacing, sponsored by Imperial College London. Recruiting at 45 sites in 3 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-22.
Sponsored by Imperial College London · Not applicable, Interventional, and Treatment
The PROTECT-HF multi-centre randomised controlled trial will compare two different pacing approaches for treating patients with slow heart rates. In it the investigators will compare a long-standing standard approach for pacing; right ventricular pacing, with a new form of pacing, physiological pacing (His and Left bundle area pacing) in 2600 patients.
Patients will be allocated at random to receive either right ventricular pacing or physiological pacing. Endpoint measurements will be undertaken at baseline, and at six-monthly intervals post-randomisation. Treatment allocation will be blinded to the endpoint assessor and the patient.
Recruitment and pacemaker implantation will be carried out at each participating centre. The primary analysis will be intention to treat. The investigators will also perform an on-treatment analysis.
2048 patients are needed to detect the expected effect size with 85% power. A total of 2600 patients will be recruited to allow for patient drop-out and crossover.
500-patient sub-study will assess within patient, and between groups, echocardiographic changes over a 24-month period to try and improve mechanistic understanding of PICM (Pacing Induced Cardiomyopathy).
Patients entering the study will attend for implantation of a pacemaker device and be randomised to either right ventricular pacing or physiological pacing.
Patients at sites participating in echo sub-study will be informed of and given opportunity to consent to echo sub-study, this will be optional to them, even if they have consented to the main study.
317 studies on the registry are indexed under Bradycardia; 71 are open to participants now.
This study's planned enrollment of 2,600 is above the median of 100 across 187 interventional studies indexed under Bradycardia.
Browse Bradycardia studies →Imperial College London is the lead sponsor of 843 studies on the registry; 180 are open to participants now.
Of its 9 completed or terminated interventional studies of FDA-regulated products, 6 (67%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
We will recruit patients who are referred for clinically indicated pacemaker implantation
Inclusion Criteria:
1. Adults aged over 18 with >35% and one or more of the following guideline based ventricular pacing indications:
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Right ventricular pacing (apical or septal lead locations as per the implanting physicians' normal practice)
Device: Pacemaker - Right Ventricular pacing
The approach for physiological pacing will be either His bundle pacing or left bundle pacing at the operator's discretion. If both of these are not achieved biventricular pacing will be performed.
Device: Pacemaker - Physiological pacing
The approach for physiological pacing will be either His bundle pacing or left bundle pacing at the operator's discretion. If both of these are not achieved biventricular pacing will be performed.
Right ventricular pacing (apical or septal lead locations as per the implanting physicians' normal practice).
Mortality
Death, any cause
Time frame: From date of consent, until date of death from any cause, assessed up until 78 months.
Heart Failure Morbidity
Adjudicated unplanned heart failure acute care (hospital admissions or ambulatory diuretic therapy i.e. diuretic lounge visit).
Time frame: From date of consent, assessed up until 78 months, or death from any cause, whichever came first.
Incidence of clinically indicated upgrade to conventional biventricular pacing (CRT device)
Time frame: From date of randomisation until the date of first documented incident of device upgrade, or death from any cause, whichever came first, assessed up to 78 months.
Patient quality of life assessed via questionnaires (EQ-5D-5L) EQ-5D is the name of the instrument and is not an acronym.
The EQ-5D-5L consists of 2 pages: the EQ-5D descriptive system and the EQ 'visual analogue scale' (EQ VAS). The descriptive system is made up of 5 sections: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each has 5 levels: no problems, slight problems, moderate problems, severe problems and extreme problems. A High score on the descriptive section means a worse health outcome. A Low score on the descriptive section means a better health outcome. A value set is required to convert the outcomes into scores. The EQ VAS records the patient's self-rated health on a vertical visual analogue scale, where the endpoints are labelled 'The best health you can imagine' and 'The worst health you can imagine'. The VAS can be used as a quantitative (numerical) measure of health outcome that reflect the patient's own judgement. A high score on the VAS means a better outcome. A low score on the VAS means a worse outcome.
Time frame: From date of consent, assessed up to 78 months or until death of any cause, whichever came first.
Patient symptoms assessed on a scale of 0-100 monthly
This questionnaire will be sent to participants on a monthly basis for the duration of the study, 78 months from one month post pacemaker implant until end of study (78 months) or death from any cause, whichever came first.
Time frame: From one month after device implant date, assessed up to 78 months or until death of any cause, whichever came first.
Safety endpoints: Device infections (requiring device extraction), pacing thresholds, need for lead revision or reimplantation, generator change, haematoma and pneumothorax
Time frame: From device implant date, assessed up to 78 months or until death of any cause, whichever came first.
Pacemaker derived endpoints: a) Atrial fibrillation (duration >6minutes) b) Ventricular arrhythmia incidence c) Daily patient activity (hours stratified by device vendor)
Time frame: From device implant date, assessed up to 78 months or until death of any cause, whichever came first.
Patient quality of life assessed via questionnaires '36-Item Short Form Health Survey' (SF-36)
A high score defines a more favourable health state. Range 0 to 100.
Time frame: From date of consent, assessed up to 78 months or until death of any cause, whichever came first.
Echo Sub-Study Endpoint: Left Ventricular End Systolic Volume (LVESV) (>10mls) within group differences
Within group differences of Left Ventricular End Systolic Volume (\>10mls) for differences according to treatment allocation.
Time frame: From baseline echocardiogram (0 to 6 weeks post pacemaker implant) to follow-up echocardiogram (24±1 months post pacemaker implant).
Echo Sub-Study Endpoint: Ejection Fraction (EF) within patient changes
Within patient changes in Ejection Fraction will be assessed for differences according to treatment allocation.
Time frame: From baseline echocardiogram (0 to 6 weeks post pacemaker implant) to follow-up echocardiogram (24±1 months post pacemaker implant).
Echo Sub-Study Endpoint: Left Ventricular End Systolic Volume (LVESV) (>10mls) within patient changes
Within patient changes of Left Ventricular End Systolic Volume (\>10mls) for differences according to treatment allocation
Time frame: From baseline echocardiogram (0 to 6 weeks post pacemaker implant) to follow-up echocardiogram (24±1 months post pacemaker implant).
Echo Sub-Study Endpoint: Ejection Fraction (EF) within group differences
Within group differences in Ejection Fraction will be assessed for differences according to treatment allocation.
Time frame: From baseline echocardiogram (0 to 6 weeks post pacemaker implant) to follow-up echocardiogram (24±1 months post pacemaker implant).
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