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

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.

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 studyMale or female aged ≥18 yearsStrict 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 diureticLVEF >35% by clinically obtained echocardiogram overread by the study core-labDemonstration of adequate echocardiographic images to allow for assessment of endpointsOn a stable guideline directed HF medical regimenFor 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 participationAbility 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 studyTreatment with another investigational drug or other intervention within 3 monthsCurrent unrevascularized coronary artery disease, unstable angina, acute MI, CABG, or PCI within the past 3 monthsSignificant 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 diseaseProlonged episodes of AF (>3 days or an AF burden >10%) within the preceding 3 monthsPresence of cardiac pacemaker or implantable cardioverter defibrillatorPrior mechanical tricuspid valve replacementPregnancy or lactation due to concerns about the effect of radiation from the pacemaker implantation procedure on the fetusKnown allergic reactions to components of the pacemaker or leadsFebrile illness within 3 days of trial enrollmentParents/guardians or participants who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures.Control Participant Exclusion Criteria: same