Metabolic Mapping and Cardiac Resynchronization

Not Applicable

Completed

Brief Summary: The purpose of this study is to gather information on the safety and effectiveness of cardiac resynchronization therapy (CRT) in patients who have mild heart failure (HF) and left bundle branch block (LBBB).

Recruitment & Eligibility

Inclusion Criteria

Left Ventricular Ejection Fraction (LVEF) 35%-50%
New York Heart Association (NYHA) class I-II
QRS duration of ≥120ms
Left bundle branch block (LBBB)
Patient is able to receive a transvenous pectoral CRT implant
Patient is able to sign informed consent
Two echocardiograms are required to confirm a stable reduced LVEF
Patient is on optimal and stable medical therapy (ACE inhibitor or angiotensin II type 1 (AT1 )blocker, beta blocker, etc. over the last 6 months)

Exclusion Criteria

Advanced comorbid conditions with life expectancy <1 year
Patient is <18 of years of age
Patient has a CRT device
Female patients who is pregnant or not on a reliable form of birth control. Women of childbearing potential are required to have negative pregnancy test within the 7 days prior to device implant
Unwilling or unable to return for required follow-up visits
Patient decides study participation is cost-prohibited

Arm && Interventions

Group	Intervention	Description
CRT-Off first, then CRT-On	Cardiac resynchronization therapy pacemaker (CRT-P)	Subjects will be randomized to have the cardiac resynchronization therapy pacemaker (CRT-P) programmed off in the first intervention period, and after six months the CRT function will be turned on in the second intervention period.
CRT-On first, then CRT-Off	Cardiac resynchronization therapy pacemaker (CRT-P)	Subjects will be randomized to have the cardiac resynchronization therapy pacemaker (CRT-P) programmed on in the first intervention period, and after six months the CRT function will be turned off in the second intervention period.

Primary Outcome Measures

Name	Time	Method
Change in Left Ventricle End-Systolic Volume Index (LVESVI)	baseline, 12 months	LVESVI is the volume of blood in the left ventricle at the end of contraction, or systole, adjusted for the individual's body surface area.
Number of Subjects Experiencing Any System-Related Complications	Approximately 12 months	This is a composite endpoint; system-related complications could include any of the following: device pocket hematoma, pneumothorax, myocardial perforation, lead dislodgement, lead revision and device-related infection.

Secondary Outcome Measures

Name	Time	Method
Number of Subjects Admitted to the Hospital for Heart Failure	Approximately 12 months	The total number of subjects hospitalized for heart failure during the study.
Change in N-Terminal Pro B-Type Natriuretic Peptide (NT-proBNP) by CRT Randomization From 6 Months to 12 Months	6 months, 12 months	The NT-proBNP is a substance that is produced in the heart and released when the heart is stretched and working hard to pump blood, measured in pg/mL. The change was calculated as the value at 12 months minus the value at 6 months.
Number of Subjects Who Experience Sustained Ventricular Tachycardia or Fibrillation Greater Than 30 Seconds	Approximately 12 months	In ventricular tachycardia, abnormal electrical signals in the ventricles cause the heart to beat faster than normal, usually 100 or more beats a minute, out of sync with the upper chambers. Ventricular fibrillation is the most serious cardiac rhythm disturbance. The lower chambers quiver and the heart can't pump any blood, causing cardiac arrest.
Change in Left Ventricular Ejection Fraction (LVEF)	Baseline, 12 months	LVEF refers to how well your left ventricle (or right ventricle) pumps blood with each heart beat. Most times, EF refers to the amount of blood being pumped out of the left ventricle each time it contracts. The left ventricle is the heart's main pumping chamber.
Number of Subjects Who Die in One Year	Approximately 12 months	The total number of subjects to die for any reason during the study.