Wiley Acta Medica Okayama 1880-4276 41 4 2025 Prevalence, Characteristics, and Arrhythmogenic Substrate of Mitral Annular Disjunction Assessed by Cardiac Magnetic Resonance Imaging in Patients With Apparently Idiopathic Ventricular Arrhythmia e70172 EN Saori Asada Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Hiroshi Morita Department of Cardiovascular Therapeutics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Norihisa Toh Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Takuro Masuda Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Akira Ueoka Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Masakazu Miyamoto Department of Cardiology, Kagawa Prefectural Central Hospital Koji Nakagawa Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Nobuhiro Nishii Kazufumi Nakamura Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Shinsuke Yuasa Department of Cardiovascular Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine and Dentistry Background: Mitral annular disjunction (MAD) is linked to an increased risk of sudden cardiac death, but its association with ventricular arrhythmias (VAs) in Japanese patients is unclear.<br> Methods: We retrospectively analyzed 129 Japanese patients with VAs and no overt structural heart disease who underwent echocardiography and cardiac MRI.<br> Results: MAD was diagnosed in 7.0%, and in 14% of patients with VAs originating from the mitral valve apparatus. MAD was significantly associated with multifocal VAs, late gadolinium enhancement in the papillary muscles, and greater mitral regurgitation.<br> Conclusion: MAD may be an important arrhythmogenic substrate in apparently idiopathic VAs among Japanese patients. No potential conflict of interest relevant to this article was reported.