Optimal Pacing Rate for Cardiac Resynchronization Therapy

This is a prospective, randomized crossover study. The objective of the study is to determine if a pacing rate of 80 beats per minute (bpm) improves exercise tolerance during the 6-minute walk test. The investigators will randomly assign half of the participants to a starting rate of 60 bpm and then switch them to a rate of 80 bpm for 3 months, and vice versa.