In this study, people will get a special Medtronic pacemaker placed in their chest. This pacemaker uses special settings to test whether a pacing rate based on each person’s body and heart helps improve heart failure symptoms. After the device is placed, people are put into one of two groups by chance. One group gets personalized pacing based on their height and heart function. The other group gets very little pacing, used only as a backup if the heart rate drops too low. Most people and study staff will not know which group they are in during the first year so the results stay fair. People will return for checkups at 2, 6, 12, 14, 18, and 24 months, and then once a year. At these visits, they may have heart images, blood tests, ECGs, questionnaires, a six minute walk test, and pacemaker checks. After the 12 month visit, everyone in the group with minimal pacing will switch to personalized pacing, and the study will continue to check safety and benefits.