B-Left HF: Biventricular Versus Left Univentricular Pacing With Implantable Cardiac Defibrillator (ICD) Back-Up in Heart Failure Patients

Inclusion Criteria: * Have an approved indication for implantation of an ICD for treatment of a life-threatening ventricular tachyarrhythmia(s) * Have advanced heart failure with a New York Heart Association (NYHA) classification of III or IV, despite receiving a minimum of 30 days of stable optimal pharmacological therapy * Have a ventricular conduction delay manifested as a QRS width \>= 130 ms * Have a left ventricular end diastolic diameter (LVEDD) \>= 55 mm * Have a left ventricular ejection fraction (LVEF) \<= 35% Exclusion Criteria: * Have a CRT device already implanted * Have a standard indication for bradycardia pacing * Have a history of chronic atrial fibrillation \[AF\] (continuous AF lasting \> 1 month) within 1 year prior to enrollment or have undergone cardioversion for AF in the past month) * Have the ability to walk \> 450 meters during the 6-minute walk test * Have uncorrected primary valvular disease * Have had a recent myocardial infarction, unstable angina or cardiac revascularization (percutaneous transluminal coronary angioplasty \[PTCA\] or coronary artery bypass graft \[CABG\]) within 1 month of enrollment * Have had cerebrovascular accident (CVA) or transient ischemic attack (TIA) within 3 months of enrollment * Have a life expectancy of less than one year * Are unable to comply with the follow-up schedule and tests * Are minors (age below 18 years) * Are pregnant or are planning for pregnancy in the next 6 months