Patients with reduced systolic ejection fraction (40≤ ejection fraction ≤55%) and pacemaker indication due to high degree AV block are included. The study has a randomized double blinded crossover design. Patients are implanted with a standard right ventricle lead and right atrial lead (if indicated), and in addition a His-bundle lead. Randomization is performed as to which pacing modality is used during the first 6 months. After 6 months the pacing modality is changed. Patients are blinded and endpoint adjudicators, including echocardiography staff, are blinded. Device nurse and physician are not blinded.~Primary endpoint is difference in left ventricular ejection fraction after 6 months, paired comparisons are used and each patient is their own control. Secondary endpoints include complications and safety of the device/electrode, and quality of life.
The study compares standard right ventricle apical pacing with so called His-bundle pacing, for patients with slightly or moderately reduced ejection fraction and atrioventricular block requiring pacemaker therapy. The primary outcome is left ventricular ejection fraction measured after 6 months.