Anti-Kv1.4 Antibody Without Myasthenia Gravis: A Rare Cause of Autoimmune Myocarditis and Myositis

Naoto Kuyama; Seiji Takashio; Takumi Nagakura; Michie Imamura; Koutaro Takamatsu; Masafumi Takae; Kyoko Hirakawa; Kenshi Yamanaga; Shinsuke Hanatani; Eiichiro Yamamoto; Kenichi Matsushita; Mitsuharu Ueda; Kenichi Tsujita

doi:10.1016/j.jaccas.2023.101734

Anti-Kv1.4 Antibody Without Myasthenia Gravis: A Rare Cause of Autoimmune Myocarditis and Myositis

JACC Case Rep. 2023 Jan 27:9:101734. doi: 10.1016/j.jaccas.2023.101734. eCollection 2023 Mar 1.

Affiliations

¹ Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
² Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.

Abstract

Anti-Kv1.4 antibody is often detected in thymoma-associated myasthenia gravis patients with anti-acetylcholine receptor antibody. Herein, we describe 2 patients with concurrent myocarditis and myositis. In both cases, anti-Kv1.4 antibody was positive despite the absence of thymoma and anti-acetylcholine receptor antibody, and immunosuppressants eventually resolved their symptoms and cardiac function. (Level of Difficulty: Advanced.).

Keywords: AChR-Ab, anti-acetylcholine receptor antibody; CK, creatinine kinase; ECG, electrocardiogram; LV, left ventricular; LVEF, left ventricular ejection fraction; MG, myasthenia gravis; TTE, transthoracic echocardiography; anti-Kv1.4 antibody; myasthenia gravis; myocarditis; myositis.

Publication types

Case Reports