['Benefits of A-V synchrony during right ventricular apical pacing are neutralized by induction of ventricular dyssynchrony. Only a few data are reported about direct His bundle pacing influence on ventricular synchronism.', 'Was to assess the capability of direct His bundle pacing to prevent pacing-induced ventricular dyssynchrony comparing DDD- (or VVI- in case of Atrial Fibrillation) right ventricular apical pacing with DDD- (or VVI-) direct His bundle pacing in the same patients cohort.', '23 of 24 patients (mean age 75.1 +/- 6.4 years) with narrow QRS (HV < 65 ms) underwent permanent direct His bundle pacing for "brady-tachy syndrome" (11) or supra-Hisian II/III-degree AV Block (permanent atrial fibrillation 7, AV Node ablation 1). A 4.1 F screw-in lead was fixed in His position, guided by endocardial pacemapping and unipolar recordings. Additional permanent (13 patients) or temporary right ventricular apical pacing leads were also positioned. Inter- and left intra-ventricular dyssynchrony, mitral regurgitation and left systolic ventricular function Tei index were assessed during either direct His bundle pacing or right ventricular apical pacing.', 'Permanent direct His bundle pacing was obtained in 23 of 24 patients. Indexes of ventricular dyssynchrony were drastically reduced, mitral regurgitation decreased and left systolic ventricular function Tei index improved during direct His bundle pacing (or His bundle and septum pacing) in comparison to apical pacing (p < 0.05). No statistically significant differences were observed between direct His bundle pacing and combined His bundle and septum pacing.'] Does permanent direct his bundle pacing induce ventricular dyssynchrony unlike conventional right ventricular apical pacing . An intrapatient acute comparison study?