Introduction: Myocardial biopsy is a fundamental procedure for diagnosing myocarditis and cardiomyopathy. Complete right bundle branch block (CRBBB) is a potential complication of right ventricular biopsy (RV-EMB) that occurs at a certain rate. Consequently, patients with complete left bundle branch block (CLBBB) often exhibit reluctance to undergo RV-EMB due to the risk of complete atrioventricular block. However, it is precisely in such cases that the diagnosis of CLBBB through myocardial biopsy becomes crucial and concerns clinicians.Although there are two approaches to RV-EMB, namely the transfemoral vein and transjuglar vein approaches, and each institution has its preferred method, no study has investigated the variation in complication rates, particularly the occurrence of CRBBB, based on the different approach sites for RV-EMB. AIMS:This study aims to analyze the disparity in complication rates, primarily CRBBB, attributable to differences in the approach site during the RV-EMB procedure. METHODS/RESULTS: Over all 266 cases who underwent RV-EMB at Kanazawa University between January 2017 and December 2022 including 87 cases with transfemoral venous approach (Group TF) and 179 cases with transjugular venous approach (Group TJ) were enrolled in this retrospective single-center study. Group TF exhibited a higher usage of warfarin (15.1% vs. 3.4%, p=0.001) and obtained fewer specimens compared to Group TJ (2.97±0.98 vs. 3.90±0.65 pieces, p<0.001).Transient CRBBB was observed in 26 (29.9%) patients in Group TF and 13 (7.3%) patients in Group TJ (p<0.001); CRBBB persisted beyond 24 hours in 8 (9.1%) and 2 (1.1%) patients(p=0.004), respectively. One case of cardiac tamponade occurred in Group TF, and two cases of VF were reported in Group TJ, with no instances of stroke, permanent pacemaker implantation, or mortality.Multivariate logistic regression analysis identified approach cite (Group TF/TJ) as an independent predictor of CRBBB (p<0.001, odds ratio 0.43). CONCLUSIONS: The transjugular venous approach in RV-EMB demonstrates potential in reducing the occurrence of CRBBB as a complication. In cases where complete atrioventricular block is a concern, such as those with CLBBB, the transjugular vein approach may be preferable.