In the increased pacing threshold (IPT) group, the pacing threshold increased by ≥0.5 V/0.24 msec within 1 month after implantation, and in the stable pacing threshold (SPT) group, the pacing threshold increased by <0.5 V/0.24 msec within 1 month after implantation. *P-values<0.05 were considered statistically significant.