AdaptResponse Clinical Trial

Inclusion Criteria:

- Subject is willing to sign and date the study Patient Informed Consent Form.

- Subject is indicated for a CRT device according to local guidelines.

- Sinus Rhythm at time of enrollment

- Complete Left Bundle Branch Block (LBBB) as documented on an ECG (within 30 days prior
to enrollment). Strauss Criteria used for LBBB.

- Intrinsic, normal AV conduction as documented on an ECG by a PR interval less than or
equal to 200ms (within 30 days prior to enrollment).

- Left ventricular ejection fraction less than or equal to 35% (documented within 180
days prior to enrollment).

- NYHA class II, III or IV (documented within 30 days prior to enrollment) despite
optimal medical therapy. Optimal medical therapy is defined as maximal tolerated dose
of Beta-blockers and a therapeutic dose of ACE-I, ARB or Aldosterone Antagonist.

Exclusion Criteria:

- Subject is less than 18 years of age (or has not reached minimum age per local law).

- Subject is not expected to remain available for at least 2 years of follow-up visits.

- Subject has permanent atrial arrhythmias for which pharmacological therapy and/or
cardioversion have been unsuccessful or have not been attempted

- Subject is, or previously has been, receiving cardiac resynchronization therapy.

- Subject is currently enrolled or planning to participate in a potentially confounding
drug or device trial during the course of this study. Co-enrollment in concurrent
trials is only allowed when documented pre-approval is obtained from the Medtronic
study manager.

- Subject has unstable angina, or experienced an acute myocardial infarction (MI) or
received coronary artery revascularization (CABG) or coronary angioplasty (PTCA)
within 30 days prior to enrollment.

- Subject has a mechanical tricuspid heart valve or is scheduled to undergo valve repair
or valve replacement during the course of the study.

- Subject is post heart transplant (subjects on the heart transplant list for the first
time are not excluded).

- Subject has a limited life expectancy due to non-cardiac causes that would not allow
completion of the study.

- Subject is pregnant (if required by local law, women of child-bearing potential must
undergo a pregnancy test within seven days prior to device implant).

- Subject meets any exclusion criteria required by local law.