This pilot study will be a multicenter randomized controlled trial involving 20 medically stable outpatients with heart failure (HF), preserved or mildly reduced LVEF (>35%), and LBBB. Patients will undergo implantation of a Medtronic Percepta CRT-P with an atrial lead, left bundle branch area pacing (LBBap) lead, and a LV lead. They will then be randomly allocated in a 1:1 fashion to usual care plus LB-CRT (DDD 60-130, LV lead turned off) (active intervention #1) or usual care plus BIV-CRT (DDD 60- 130, LV lead turned on) (active intervention #2).
Primary Objective - To determine if implantation of a permanent CRT pacing device (with LB-CRT, or conventional BiV-CRT with a coronary sinus LV lead) can improve electromechanical function, HF symptoms, and natriuretic peptide levels among patients with symptomatic HF, LVEF > 35%, and LBBB.