Left vs Left Randomized Clinical Trial

Inclusion Criteria:

• Men and women 18 years of age or older.

• A LVEF ≤ 50% within 6 months prior to enrollment.

• Resting QRS duration ≥130 ms as evidenced by a historical 12-lead ECG prior toenrollment OR anticipated right ventricular pacing >40% OR device in place withright ventricular pacing > 40%.

• Are optimized on HF guideline directed medical therapy according to current HFpublished guidelines OR patient's physician will make an effort to start allguideline-directed medical therapy and titrate doses up as permitted by theparticipant clinical status and co-morbidities prior to implantation procedure.

Exclusion Criteria:

• Women who are pregnant, lactating, or plan to become pregnant during the course ofthe trial.

• Participants with angiographic evidence of coronary disease who are candidates forcoronary revascularization and are likely to undergo coronary artery bypass graftsurgery or percutaneous coronary, intervention in the next three (3) months.

• Enzyme-positive myocardial infarction within the past three (3) months prior toenrollment.

• Coronary artery bypass graft surgery or percutaneous coronary intervention (balloonand/or stent angioplasty) within the past three (3) months prior to enrollment.

• Reversible non-ischemic cardiomyopathy (e.g., acute viral myocarditis).

• Participants with Chagas disease, cardiac sarcoidosis or amyloidosis.

• Expected to receive left ventricular assist device or heart transplantation within 6months.

• Participants with primary severe valvular disease (e.g., aortic stenosis).

• Have a life expectancy of less than 12 months.

• Participants with irreversible brain damage from preexisting cerebral disease.

• Participants with a contrast dye allergy unable or unwilling to undergo pretreatmentwith steroids and/or diphenhydramine.

• Participants participating in any other interventional cardiovascular clinicaltrial.

• Participants who would be unable to comply with the study's follow-up visitschedule; or

• Participants who had any prior unsuccessful attempt at implantation of biventricularpacing (BiVP), His Bundle Pacing (HBP), or Left Bundle Branch Pacing (LBBP) device.