Effect of Targeting Left Ventricular Lead Position on the Rate of Response to Cardiac Resynchronization Therapy.

Inclusion Criteria: * LV EF ≤ 0.40 measured within 3 months of enrollment, * SAS class 3 or 4 symptoms indicative of moderate to severe functional capacity limitation due to heart failure within 1 month of enrollment. * Confirmed dyssynchrony on screening echo (1.1.9), \& * On stable doses of ACE inhibitor or angiotensin II blocker \& a beta-blocker for ≥ 2 months unless medically contra-indicated. * Controlled heart rate if in permanent AF (resting \<70 \& maximal \<120). Exclusion Criteria: * Unable or unwilling to provide informed consent, * Medical condition other than heart failure likely to cause death \< 1 year, * Cardiac transplant planned within 6 months, * Known contra-indication to transvenous CRT device implant (e.g., active sepsis, artificial tricuspid valve, known vascular occlusion that will prevent delivery of leads transvenously), * Clinically significant myocardial infarction within last 2 months, or * Coronary bypass graft surgery ≤ 2 months or coronary angioplasty ≤ 1 month