The study is a prospective, non-randomized, multi-center, observational, pre-market clinical study. The study is expected to be conducted at up to 30 centers in the United States. Up to 300 subjects will be enrolled to achieve approximately 40 heart failure events (no more than two per subject will contribute to the cumulative total). Study subjects will be followed for up to 3 years post-insertion or until official study closure defined as when Medtronic and/or regulatory requirements have been satisfied per the Clinical Investigation Plan and/or by a decision by Medtronic or regulatory authority, whichever occurs first. The expected study duration is approximately 4 years representing 1.5 years of enrollments and 2.5 years of follow-up.