Pacing-Induced Cardiomyopathy

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 investigators aim to prospectively test the comparative effectiveness of His or Left bundle branch pacing in relation to patient centered outcomes (quality of life, physical activity, heart failure hospitalization, mortality) and comparative safety in relation to device-related complications and re-interventions (e.g., lead dislodgement, infection) relative to standard of care biventricular pacing in patients with heart failure due to left ventricular systolic dysfunction (LVEF≤50%) and with either a wide QRS (≥130 ms) or with/anticipated \>40% pacing who are already receiving current standard heart failure pharmacological therapy.

Right ventricular pacing causes ventricular dyssynchrony and may be associated with impaired outcome. In the last decade, several approaches for more physiological pacing became available and were implemented in the latest guidelines. However, compared to conventional device implantation, cardiac resynchronization, His bundle pacing and left bundle area pacing remain demanding procedures in the individual case. Goal of the single center observational "Pace conduct" study is to evaluate implantation success, safety and outcome of pacing methods that maintain physiologic ventricular activation.

It is unknown whether left bundle branch area pacing (LBBAP) or biventricular pacing best prevents or reverses left ventricular (LV) adverse remodelling in patients with atrial fibrillation (AF) who require ventricular pacing or CRT. This randomized non-inferiority cross-over trial will compare left ventricular end-systolic volume change and secondary endpoints between LBBAP and biventricular pacing in patients with AF and LV dysfunction.