Strategic Management to Improve CRT Using Multi-Site Pacing Post Approval Study (Reference # C1918)

Evaluate the effectiveness of Boston Scientific (BSC)'s LV MSP (Left Ventricular MultiSite
Pacing) feature in the Resonate family of CRT-D devices1 and confirm safety in a post
approval study when used in accordance with its approved labeling.

Inclusion Criteria:

1. Subjects who received de novo implantation of BSC's Resonate family of CRT-D devices
with the LV MSP feature4 and BSC's ACUITYTM X4 LV Quadripolar leads. A Resonate family
of CRT-D device upgrade from previous single or dual chamber pacemaker or ICD
implantation is allowed.

2. Subjects must meet BSC labeled indication for CRT-D implantation.

3. Subjects must have a functional RA lead and RV lead implanted

4. Subjects who are willing and capable of providing informed consent

5. Subjects who are willing and capable of participating in all testing/visits associated
with this clinical study at an approved clinical study center and at the intervals
defined by this protocol

6. Subjects who are age 18 and above, or of legal age to give informed consent specific
to state and national law

Exclusion Criteria:

1. Subjects who received LV pacing prior to receiving the Resonate family of CRT-D system
implantation.

2. Subjects who received the LV MSP therapy post CRT-D implantation but prior to
enrollment

3. Subjects with documented history of permanent AF

4. Subjects with documented permanent complete AV block

5. Subjects who are expected to receive a heart transplant during the 12 months course of
the study

6. Subjects with documented life expectancy of less than 12 months

7. Subjects who enrolled in any other concurrent study or registry, with the exception of
mandatory national or governmental registry, without prior written approval from BSC