Physiological Versus Right Ventricular Outcome Trial Evaluated for Bradycardia Treatment Upgrades (PROTECT-UP)

Guidelines for patients having first-time implants advocate that even when heart function is only mildly impaired, modern pacing approaches should be utilised to avoid the potentially damaging effects of RV pacing to preventing symptoms from pacing induced or worsened cardiomyopathy. However, once a traditional (RV) pacemaker is implanted, development of impaired heart function does not prompt a device upgrade. Even at the end of battery life, physicians simply replace it like-for-like. This trial tests whether such patients have better symptoms and quality of life if changed to a modern physiological pacing strategy from the traditional RV pacing approach. In this crossover trial, participants will be upgraded to a physiological pacing strategy. After their procedure, they will have a one-month run-in period to recover from the procedure (their pacemaker will be programmed to continued RV pacing). They will be have 2 one-month blinded time periods, randomised to physiological pacing or right ventricular pacing alternately. They will subsequently undergo two six-month blinded randomised time periods. Patients will document symptoms monthly on a mobile phone application or computer. At the end of each time period, they will have measurements of heart function, a walking test and quality-of-life questionnaires including the SF-36 questionnaire. The investigators hypothesise that upgrading to physiological pacing strategies will improve patients' quality of life.

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)

The approach for physiological pacing upgrade 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).

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. 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.

Device infections (requiring device extraction), pacing thresholds, need for lead revision or reimplantation, generator change, haematoma and pneumothorax

From device implant date, assessed up to 15 months at the end of the trial (including a one-month run-in period post-procedure prior to the first baseline visit)

Patients with an RV pacemaker and LVEF 35-50% who are clinically indicated for a cardiac resynchronisation therapy upgrade procedure and: EF reduced by >5% of increase in LVESV by 10ml since implant NT-proBNP >250ng/L in sinus rhythm NT-proBNP > 750 Ng/L if AF Left atrial volume index > 30ml/m2 Regular loop diuretics prescribed Decline in daily patient activity by >1 hour per day since implant Decrease in device measured thoracic impedance Patient reported decline in functional class or exercise tolerance Exclusion Criteria: Those unable to provide informed consent Patients under age 18 Pregnant women