The purpose of this study is to analyze the effect of left ventricular lead pacing location in the non-left bundle branch block (non-LBBB) heart failure patient population. The left ventricular lead pacing location will be guided by either the pacing site with the largest amount of dyssynchrony as measured by the LV electrical delay (QLV) or the physician's standard of care implant approach.

This is a prospective, pilot, multi-center, double-blinded, randomized post-market study to assess the effect of left ventricular lead pacing location (guided via QLV measurement vs. standard of care approach) in non-LBBB patients.

In the QLV arm the physician will:

1. Assess two branches of the coronary sinus - a non-traditional vessel (inclusive of the anterior region) will be tested first and a traditional free lateral branch will be tested second for LV lead placement.
2. Measure QLV for each of the four cathodes of the left ventricular lead in each branch.
3. Choose the vein branch and cathode with the longest QLV measurement and program a vector based on that cathode.

In the standard of care group, the left ventricular lead placement will be carried out according to the physician's standard of care implant approach.

The impact of the left ventricular lead position will be evaluated based on the patient's response to CRT utilizing the Clinical Composite Score (cardiovascular death, heart failure hospitalizations, New York Heart Association (NYHA) class, and Patient Global Assessment). Authorized site personnel conducting the NYHA class assessment and Patient Global Assessment will be blinded to the randomization assignment and lead implant technique.

Inclusion Criteria:

• Have non-LBBB morphology (includes complete right bundle branch block and intraventricular conduction delay with a QRS duration ≥ 120ms)

• Have the following indication per the 2013 updated American College of Cardiology Foundation/American Heart Association/Heart Rhythm Society guidelines:

  • Left ventricular ejection fraction (LVEF) ≤ 35%, sinus rhythm, ischemic or non-ischemic cardiomyopathy, a non-LBBB pattern with QRS duration ≥ 120 ms, and NYHA) class III/ambulatory class IV on guideline directed medical therapy

• Receiving a new CRT implant or undergoing an upgrade from an existing implantable cardioverter defibrillator or pacemaker implant with no more than 10% right ventricular pacing

• Are 18 years or older, or of legal age to give informed consent specific to state and local law

• Ability to provide informed consent for study participation and is willing and able to comply with the prescribed follow-up tests and schedule of evaluations

Exclusion Criteria:

• Irreversible occlusion of venous access that will prevent placement of the CRT system either through the right or left upper extremity venous system
• Undergoing left ventricular lead placement via a surgical or epicardial approach
• Cardiomyopathy due solely to valvular disease that is not repaired/replaced
• Enrolled or intend to participate in a clinical drug and/or device study, which could confound the results of this trial as determined by St. Jude Medical, during the course of this clinical study
• LBBB: QRS width ≥ 120 ms, with predominantly negative QRS in lead V1, and upright, monophasic QRS in leads I and V6
• Incomplete right bundle branch block - intraventricular conduction delay with a QRS duration between 110 and 119ms
• Persistent or permanent atrial fibrillation
• Pacemaker dependent
• Patients who are being upgraded primarily due to right ventricular pacing
• Women who are pregnant or who plan to become pregnant during the clinical trial
• Life expectancy < 1 year