ABSTRACT Background: Little is known about the occurrence of unknown preexisting conduction disturbances/sinus node dysfunction (CDs/SND) in transcatheter aortic valve replacement (TAVR) patients. Preexisting CDs/SND could be a possible predictor for permanent pacemaker (PPM) implantation post-TAVR. In this pilot study, we aimed to investigate the additive value of pre-TAVR 24-hour Holter monitoring (HM) to diagnose unknown preexisting CDs/SND for predicting PPM implantation post- TAVR. Methods: This single-center and retrospective pilot study included 164 patients. 24-hour HM and a 12-lead electrocardiogram (ECG) were performed within a month prior to TAVR. All HM and ECG data were analyzed for CDs/SND events. Results: HM identified in 33 patients (20%) unknown preexisting events of CDs/SND in addition to baseline ECG. Among these patients, only four required a PPM implantation post-TAVR (2% of all patients). No difference in PPM rate was observed between patients with and without new CDs/SND events on HM (11% vs. 12%, p = 1.00). Conclusions: Unknown preexisting CDs and SND are prevalent on HM in 20% of TAVR patients. No difference in PPM rate between patients with and without these newly diagnosed CDs/SND was observed. Therefore, the clinical benefit of 24-hour HM in TAVR candidates has not been convincingly demonstrated. Abbreviations: AF: atrial fibrillation/flutter; AMI: acute myocardial infarction; AV: atrioventricular; AVA: aortic valve area; AVB: atrioventricular block; CD: conduction disturbance; ECG: electrocardiogram; HM: Holter monitoring; IV: intraventricular; LBBB: left bundle branch block; LVF: left ventricular function; NSIVCD: nonspecific intraventricular conduction disturbance; NYHA: New York Heart Association; TAVR: transcatheter aortic valve replacement; PPM: permanent pacemaker; RBBB: right bundle branch block; SR: sinus rhythm; SND: sinus node dysfunction; TIA: transient ischemic attack