POsition of Leads in Advanced heaRt Failure: the POLAR Study

Inclusion Criteria: * Subject meets the general indications for an implantable cardioverter defibrillator (ICD) with LV systolic function ≤ 35% as defined by echocardiography. * Subject has moderate or severe heart failure, defined as NYHA Class III-IV for at least 90 days prior to enrollment. * Subject has optimal pharmacological heart failure therapy for at least 30 days prior to enrollment. * Subject has a 12-lead electrocardiogram (ECG) obtained no more than 90 days prior to enrollment documenting a sinus rate \> 50 bpm and PR interval \< 320 ms measured from any two leads. * 12 lead ECG with left bundle brunch block morphology and a QRS duration of at least 120 msec. * Subject has creatinine \< 2.5 mg/dL obtained no more than 30 days prior to enrollment. * Subject has left ventricular ejection fraction \< 35% by echocardiogram no more than 1 year prior to enrollment. * Subject is willing and capable of undergoing a device implant and participating in all testing associated with this clinical investigation. * Subject has a life expectancy of more than 180 days, per physician discretion. * Subject is age 18 or above, or of legal age to give informed consent specific to state and national law. Exclusion Criteria: * Subject has right bundle branch block morphology on a 12-lead ECG obtained no more than 90 days prior to enrollment. * Subject had previous cardiac resynchronization therapy, a previous coronary venous lead, or meets the general indications for anti-bradycardia pacing defined as ventricular pacing \> 40% by pacemaker interrogation. * Subject has a neuromuscular, orthopedic, or other non-cardiac condition that prevents normal, unsupported walking. * Subject has an atrial tachyarrhythmia that is permanent (i.e., does not terminate spontaneously and cannot be terminated with medical intervention) or persistent (i.e., can be terminated with medical intervention, but does not terminate spontaneously) within 30 days prior to enrollment. * Subject currently requires dialysis. * Subject has severe chronic obstructive pulmonary disease (COPD), defined as FEV1/FVC \< 60%, or as defined by a physician. * Subject has had a myocardial infarction within 30 days prior to enrollment or coronary artery disease (CAD) in which surgical or percutaneous correction was performed within 30 days prior to enrollment. * Subject has hypertrophic obstructive cardiomyopathy or infiltrative cardiomyopathy (e.g., amyloidosis, sarcoidosis). * Subject is on IV inotropic agents. * Subject has any mitral valve prosthesis, or a mechanical aortic or tricuspid prosthesis * Subject is enrolled in any concurrent study, without Medtronic written approval, which may confound the results of this study. * Subject is pregnant or planning to get pregnant. * Subject requires oxygen for medical reasons other than CHF.