Myocardial Work and Metabolism in CRT

Exclusion Criteria

• •Impossible to obtain LV volumes by echocardiography.
• •Right bundle branch block.
• •Permanent atrial fibrillation, flutter or tachycardia (\>100 bpm).
• •Recent myocardial infarction, within 40 days prior to enrolment.
• •Subject underwent coronary artery bypass graft (CABG) or valve surgery, within 90 days.
• •Post heart transplantation, or is actively listed on the transplantation list, or has reasonable probability (per investigator's discretion) of undergoing transplantation in the next year.
• •Implanted with a LV assist device (LVAD), or has reasonable probability (per investigator's discretion) of receiving a LVAD in the next year.
• •Severe aortic stenosis (with a valve area of \<1.0 cm2 or significant valve disease expected to be operated on within study period).
• •Complex and uncorrected congenital heart disease.
• •Breastfeeding women, women of child bearing potential.
• •Enrolled in one or more concurrent studies that would confound the results of this study.