Left Ventricular Outflow Tract Obstruction Due to Accessory Mitral Valve Tissue: An Unusual Systolic Murmur in an Elderly Patient

Kohei Kurogi; Tomoaki Taniguchi; Yunosuke Matsuura; Yoshimasa Yamamura; Nozomi Watanabe; Koji Furukawa; Koichi Kaikita

doi:10.1016/j.jaccas.2025.106288

Left Ventricular Outflow Tract Obstruction Due to Accessory Mitral Valve Tissue: An Unusual Systolic Murmur in an Elderly Patient

JACC Case Rep. 2026 Feb 4;31(5):106288. doi: 10.1016/j.jaccas.2025.106288. Epub 2025 Dec 4.

Authors

Kohei Kurogi¹, Tomoaki Taniguchi², Yunosuke Matsuura³, Yoshimasa Yamamura¹, Nozomi Watanabe⁴, Koji Furukawa², Koichi Kaikita¹

Affiliations

¹ Division of Cardiovascular Medicine and Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
² Faculty of Medicine, Department of Cardiovascular Surgery, University of Miyazaki, Miyazaki, Japan.
³ Division of Cardiovascular Medicine and Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan. Electronic address: yunosuke_matsuura@med.miyazaki-u.ac.jp.
⁴ Faculty of Medicine, Division of Cardiovascular Physiology, University of Miyazaki, Miyazaki, Japan.

Abstract

Background: Accessory mitral valve tissue (AMVT) is a rare congenital anomaly that is typically diagnosed during childhood and overlooked in elderly patients presenting with left ventricular outflow tract (LVOT) obstruction.

Case summary: A 73-year-old man presented with exertional presyncope and a systolic murmur. Transthoracic echocardiography revealed a mobile sac-like structure protruding into the LVOT, causing a 74 mm Hg gradient despite a normal aortic valve. Multimodal imaging confirmed a type IIB2 AMVT with dynamic prolapse. Surgical resection and histological analysis confirmed valve-like tissues. At the 3-year follow-up, the patient had remained asymptomatic with no recurrence.

Discussion: This case shows that AMVT, although congenital, can rarely present in elderly individuals. A crescendo systolic murmur with beat-to-beat variability aids diagnosis. Multimodal imaging is critical for diagnosis and surgical planning. Prompt excision and careful perioperative management ensure durable relief and favorable long-term outcomes.

Take-home messages: AMVT, although congenital, can present as LVOT obstruction, even in elderly patients. A crescendo systolic murmur with beat-to-beat variability is a clinical sign of dynamic obstruction caused by AMVT.

Keywords: accessory mitral valve tissue; case report; congenital heart disease; elderly patient; left ventricular outflow tract obstruction; multimodality imaging.

Publication types

Case Reports