Adaptive CRT Effect on Electrical Dyssynchrony

Inclusion criteria

• Patient has a standard class I or class II indications for CRT-P or CRT-D implantation in accordance with ACC/AHA/HRS guidelines (2012 ACCF/AHA/HRS Focused Update Incorporated Into the ACCF/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities)2.At least 18 years of age at the time of consent
• Is willing and able to comply with the protocol

Exclusion criteria

• Chronic atrial arrhythmias defined as: "Atrial fibrillation is permanent when it has resisted all attempts to restore sinus rhythm or when the physician and patient decide that no such attempt should be made."
• Patient has ever had a previous or has an existing CRT system, ICD, or pacemaker.
• GFR <30ml/min
• Patient has had unstable angina, acute myocardial infarction, coronary artery bypass graft surgery, or percutaneous transluminal coronary angioplasty within 30 days prior to study enrollment
• Patient has primary valvular disease and is indicated for valve repair or replacement
• Patient is enrolled in ≥1 concurrent studies that would confound the study results (any other interventional trial)
• Patient is pregnant or of childbearing potential and not on a reliable form of birth control. All women of child-bearing potential must undergo a pregnancy test.
• Patient status post heart transplant
• Patient has been classified as NYHA functional class IV within 3 months prior to study enrollment
• concomitant conditions other than cardiac diseases that were associated with a higher likelihood of death during 1 year after enrollment
• Patient, legal guardian or authorized representative is unable or unwilling to cooperate or give written informed consent