The purpose of this study is to gather information on how doctors program particular settings on cardiac resynchronization therapy implantable cardiac defibrillators (CRT-Ds), to analyze how these settings affect the amount of cardiac resynchronization therapy (CRT) patients receive and to evaluate the therapy approach for converting abnormally fast heartbeats into normal heartbeats. There are no experimental devices or procedures involved in this study.

Inclusion Criteria:

• Patient is indicated for a Medtronic CRT-D system
• Patient is willing to sign Permission for Access to and Use of Health Information form
• Patient is willing and able to comply with follow-up visits through six months

Exclusion Criteria:

• Patient has a life expectancy of less than 6 months
• Patient is participating in any concurrent study that could confound the results for either study