Effects of Mavacamten on Cardiac Magnetic Resonance Features in Chinese Patients With Obstructive Hypertrophic Cardiomyopathy

Zhuang Tian; Liwen Li; Xiaoyan Li; Qing Zhang; Daoquan Peng; Wei Ma; Ping Yang; Fang Wang; Xiang Cheng; Yiqun Fu; Jing Sun; Jian'an Wang; Shuyang Zhang

doi:10.1016/j.jacasi.2025.05.015

Effects of Mavacamten on Cardiac Magnetic Resonance Features in Chinese Patients With Obstructive Hypertrophic Cardiomyopathy

JACC Asia. 2025 Jun 24:S2772-3747(25)00288-1. doi: 10.1016/j.jacasi.2025.05.015. Online ahead of print.

Authors

Zhuang Tian¹, Liwen Li², Xiaoyan Li³, Qing Zhang⁴, Daoquan Peng⁵, Wei Ma⁶, Ping Yang⁷, Fang Wang⁸, Xiang Cheng⁹, Yiqun Fu¹⁰, Jing Sun¹¹, Jian'an Wang¹², Shuyang Zhang¹³

Affiliations

¹ Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
² Department of Cardiology, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Southern Medical University, Guangzhou, China.
³ Renmin Hospital of Wuhan University, Hubei General Hospital, Wuhan, China.
⁴ West China Hospital, Sichuan University, Chengdu, China.
⁵ The Second Xiangya Hospital of Central South University, Changsha, China.
⁶ Peking University First Hospital, Beijing, China.
⁷ China-Japan Union Hospital of Jilin University, Changchun, China.
⁸ Department of Cardiology, Beijing Hospital, National Center of Gerontology; Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China.
⁹ Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
¹⁰ Shanghai LianBio Development Co. Ltd, Shanghai, China.
¹¹ Bristol Myers Squibb, Shanghai, China.
¹² The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China. Electronic address: wangjianan111@zju.edu.cn.
¹³ Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. Electronic address: shuyangzhang103@nrdrs.org.

PMID: 40632050
DOI: 10.1016/j.jacasi.2025.05.015

Abstract

Background: Mavacamten, a first-in-class cardiac myosin inhibitor and the only approved cardiac myosin inhibitor worldwide, improved clinical symptoms and health status in patients with symptomatic obstructive hypertrophic cardiomyopathy (HCM) in phase 3 EXPLORER-HCM (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy) (NCT03470545) and EXPLORER-CN (A Study to Evaluate the Efficacy and Safety of Mavacamten in Chinese Adults With Symptomatic Obstructive HCM) (NCT05174416).

Objectives: The purpose of this work was to study the effect of mavacamten on cardiac structure and function by cardiac magnetic resonance (CMR) imaging in Chinese participants in EXPLORER-CN.

Methods: Eligible patients with obstructive HCM underwent CMR imaging at screening and week 30. Change from baseline to week 30 in left ventricular (LV) mass index was analyzed as a prespecified secondary outcome. Prespecified exploratory outcomes included changes in cellular hypertrophy, cardiac structure and function, and myocardial fibrosis by CMR.

Results: Among 81 patients randomized, 58 patients (mean age 51.2 years, 74.1% men) with CMR data available were analyzed (mavacamten, n = 39; placebo, n = 19). After 30 weeks, greater reductions from baseline were observed (mean between-group difference) with mavacamten vs placebo in LV mass index (-30.8 g/m² [95% CI: -41.5 to -20.1 g/m²]), maximal LV wall thickness (-3.5 mm [95% CI: -4.7 to -2.4 mm]), and maximal left atrial volume index (-18.3 mL/m² [95% CI: -26.7 to -9.8 mL/m²]); all nominal P < 0.001. Reduction from baseline to week 30 in global mass of late gadolinium enhancement by 6 SDs was also observed with mavacamten vs placebo (mean between-group difference, -2.0 g [95% CI: -11.9 to 8.0 g]; nominal P = 0.007).

Conclusions: At 30 weeks, improvements were observed in measures of cardiac structure and function, with reductions in indicators of myocardial fibrosis, in the mavacamten vs the placebo group. (A Study to Evaluate the Efficacy and Safety of Mavacamten in Chinese Adults With Symptomatic Obstructive HCM; NCT05174416).

Keywords: cardiac magnetic resonance; mavacamten; obstructive hypertrophic cardiomyopathy.

Associated data

ClinicalTrials.gov/NCT05174416