Follow-up
Baseline electrocardiographic (ECG) and echocardiographic parameters were acquired from the ECG and echocardiography performed nearest to the implant date. Pacing-lead locations were reviewed using anteroposterior, right-oblique, and left-oblique views after implantation. PPM records were obtained at regular intervals (at least 6 months), and the ventricular pacing burden (ventricular pacing percentage) was obtained by telemetry at the follow-up. The pacing QRS duration was measured within 3 days after PPM implantation from the surface 12-lead ECG. Patients visited the outpatient department at regular intervals (3-6 months).