CLINICAL TRIAL / NCT05265520

Inclusion Criteria: - Age 18 years or older (no upper age limit) - Optimal medical therapy for heart failure by current guidelines - Class IIa or IIb guideline-based indication for CRT-D implant in RBBB patients, including one of the following: - New York Heart Association (NYHA) class II HF symptoms, LVEF ≤ 30% and QRS≥ 150 ms (IIb); OR - NYHA class III-IV a HF, LVEF ≤ 35%, and QRS duration ≥ 150 ms (IIa); OR - NYHA class III-IV a HF, LVEF ≤ 35%, and QRS duration 120-149 ms (IIb) Exclusion Criteria: - Unable to obtain most recent imaging data from echocardiogram within 1 year prior to date of randomization - Left bundle branch block (LBBB) or intraventricular conduction delay (IVCD) ECG morphology - Unable or unwilling to follow study protocol - Less than 12 months life expectancy at consent - Pregnancy or planned pregnancy during duration of the study - On heart transplant list or likely to undergo heart transplant