Purpose To evaluate left ventricular systolic synchronization during permanent direct His Bundle pacing.Methods A total of 42 patients who met class Ⅰ or class Ⅱa indications for device-based therapy of cardiac rhythm abnormalities were enrolled and randomly assigned to perform either direct His Bundle pacing (DHBP) or right ventricular apical pacing (RVA).A quadrupolar electrophysiology catheter was advanced to locate His bundle and a 4F active pacing lead were introduced to perform his bundle pacing.Regular follow up was performed and pacing parameters were studied during the time spot of three month after pacemaker implantation.