Implementation of a Protocol Utilizing Adaptive CRT in a Normal AV Conduction, CRT Non-Response Population at Generator Replacement

Inclusion Criteria

• •Normal AV conduction (SAV\<220 ms or PAV\<270 MS)
• •Left Bundle Branch Block (defined as \> or = to 140 ms (male) or \> or = 130 (female), QR or rS in leads V1 and V2, and Mid QRS notching or slurring in v 2 of leads V1, V2, V5, V6 and I and aVL.)
• •Patient and/or physician assessment or unchanged or worsened heart failure status at the time of recommended replacement time (RRT) for previous CRT device.
• •Sinus Rhythm at the time of enrollment