REsynchronization Comparison In LBBB and Normal or Mildly Reduced VENTricular Function With CRT (REINVENT-CRT) (REINVENT)

Inclusion Criteria: Ability to understand and the willingness to sign a written informed consent form and HIPAA Authorization. Stated willingness to comply with all study procedures and availability for the duration of the study Male or female aged ≥18 years Strict LBBB defined as QRS duration ≥130ms in women and ≥140ms in men, a QS or rS complex in V1 and V2, as well as notching or QRS slurring in mid-QRS in ≥2 contiguous leads. NYHA II/III, ambulatory NYHA IV, or NYHA I HF with any prior history of HF symptom decompensation requiring hospitalization, ED visit, or outpatient visit for care with IV diuretic LVEF >35% by clinically obtained echocardiogram overread by the study core-lab Demonstration of adequate echocardiographic images to allow for assessment of endpoints On a stable guideline directed HF medical regimen For females of reproductive potential: use of a highly effective contraception for at least 1 month prior to screening and agreement to use such a method during study participation Ability to understand and the willingness to sign a written informed consent form and HIPAA Authorization. Exclusion Criteria: Patients with anticipated addition or titration of HF medical therapies (ACE/ARB/ARNI, beta blocker, MRA, SGLT2 inhibitor) during the duration of the study Treatment with another investigational drug or other intervention within 3 months Current unrevascularized coronary artery disease, unstable angina, acute MI, CABG, or PCI within the past 3 months Significant non-functional mitral or aortic valvular disease (severe stenosis or regurgitation) Significant structural heart [including hypertrophic cardiomyopathy (septal thickness ≥15 mm) or infiltrative cardiomyopathy (eg. amyloid)] Current moderate to severe pulmonary hypertension (right ventricular systolic pressure of ≥40 mmHg) Oxygen dependent chronic lung disease Prolonged episodes of AF (>3 days or an AF burden >10%) within the preceding 3 months Presence of cardiac pacemaker or implantable cardioverter defibrillator Prior mechanical tricuspid valve replacement Pregnancy or lactation due to concerns about the effect of radiation from the pacemaker implantation procedure on the fetus Known allergic reactions to components of the pacemaker or leads Febrile illness within 3 days of trial enrollment Parents/guardians or participants who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures. Control Participant Exclusion Criteria: same