After signing a consent form but prior to randomization and enrollment, the pacemaker rate will be set at 60 and then a 24 hour assessment by Holter monitor will be obtained. Patients will be eligible for the study if they are paced at least 75% of the time. For rate responsive pacemakers, the pacemaker will be set at a lower rate of 60 and an upper rate of 80. Patients will need to be paced at a rate of 60 beats per minute at least 75% of the time for these patients as well.