What is the clinical evidence from this study?

Study design: RCT. Population: Symptomatic obstructive hypertrophic cardiomyopathy (n=81). Intervention: Mavacamten vs. Placebo. Primary outcome: Change in KCCQ-23 Clinical Summary Score (CSS) from baseline to week 30 (LSM difference 10.2, 95% CI 4.4-16.1, p=<0.001).

What does this research mean for the field?

Long-term mavacamten treatment for up to 78 weeks provides sustained improvements in patient-reported health status and quality of life in Chinese patients with symptomatic obstructive hypertrophic cardiomyopathy. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

May 21, 2026Cardiology and Therapy0 citationsOpen Access

Mavacamten in Chinese Patients with Obstructive Hypertrophic Cardiomyopathy: Patient-Reported Health Status Analysis up to 78 Weeks in the EXPLORER-CN Study

Q: What are the key findings of this study?

Mavacamten significantly improved patient-reported health status compared to placebo, with a least squares mean difference in KCCQ-23 clinical summary score of 10.2 at 30 weeks.

Q: What does this research mean for the field?

Long-term mavacamten treatment for up to 78 weeks provides sustained improvements in patient-reported health status and quality of life in Chinese patients with symptomatic obstructive hypertrophic cardiomyopathy. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

ZTZhuang TianChinese Academy of Medical Sciences & Peking Union Medical College XLXiaoyan LiWuhan University LLLiwen LiGuangdong Academy of Medical Sciences

Key Result

Mavacamten significantly improved patient-reported health status compared to placebo, with a least squares mean difference in KCCQ-23 clinical summary score of 10.2 at 30 weeks.

Study Design

Type

RCT (n=81)

Blinding

Double-blind

Randomization

2:1

Multicenter

Yes

Structured PICO

Does mavacamten improve patient-reported health status in Chinese patients with symptomatic obstructive hypertrophic cardiomyopathy?

Population

81 adult patients (age ≥ 18 years, body weight > 45 kg) with symptomatic obstructive hypertrophic cardiomyopathy (peak LVOT gradient ≥ 50 mmHg at rest or after Valsalva, LVEF ≥ 55%, NYHA class II or III) in China. Mean age 51.9, 71.6% male.

Intervention

Mavacamten starting at 2.5 mg oral once daily (adjusted via pharmacodynamics-based dose titration) for 30 weeks, followed by a 48-week long-term extension period (up to 78 weeks total).

Comparator

Matching placebo once daily for 30 weeks (during the double-blind period), after which patients switched to mavacamten 2.5 mg once daily for the 48-week extension.

Outcome

Patient-reported health status measured by the 23-item Kansas City Cardiomyopathy Questionnaire (KCCQ-23) Clinical Summary Score (CSS), Overall Symptom Score (OSS), and Total Symptom Score (TSS) at week 30 and week 78.patient reported

Mavacamten provides significant and sustained improvements in patient-reported health status and quality of life up to 78 weeks in Chinese patients with symptomatic obstructive hypertrophic cardiomyopathy.

Main Result

Effect estimate: LSM difference 10.2 (95% CI 4.4-16.1)

Absolute Event Rate: 5.7% vs -5.4%

p-value: p=<0.001

Limitations

Relatively modest sample size limits the generalizability of the findings
Outcomes assessed during the long-term extension period were descriptive in nature
Does not report concurrent analyses of cardiac structural and functional markers
Study period coincided with the COVID-19 pandemic, which may have impacted patient health status

Abstract

INTRODUCTION: Improvement of symptoms, physical function, and quality of life is one treatment goal for patients with obstructive hypertrophic cardiomyopathy (HCM). Mavacamten improved left-ventricular outflow tract gradients in Chinese patients with obstructive HCM in the EXPLORER-CN trial. We report here a detailed analysis of patient-reported health status per the 23-item Kansas City Cardiomyopathy Questionnaire (KCCQ-23) in Chinese patients after 78 weeks of mavacamten. METHODS: Patients who completed the double-blind, placebo-controlled (DBPC) period of EXPLORER-CN with no active safety concerns could enter a long-term extension (LTE) period to receive mavacamten for 48 weeks at either the 30-week dose (mavacamten-mavacamten group) or a once-daily starting dose of 2.5 mg (subsequently adjusted via pharmacodynamics-based dose titration: placebo-mavacamten group). Health status endpoints included KCCQ-23 clinical summary score (CSS), overall symptom score (OSS), total symptom score (TSS), physical limitations score, and quality-of-life scores through week 78. Week 78 endpoint analyses were descriptive. RESULTS: In the DBPC period, 54 patients received mavacamten and 27 received placebo; of these, 54 and 25, respectively, entered the LTE period. KCCQ-23 CSS, OSS, and TSS improved with mavacamten and worsened with placebo during the DBPC period (mean change baseline to week 30: 5.7, 6.4, and 8.1, respectively mavacamten-mavacamten group and - 5.4, - 4.3, and - 4.8, respectively placebo-mavacamten group). CSS, OSS, and TSS continued to improve in the mavacamten-mavacamten group during the LTE period (mean change baseline to week 78: 7.1, 8.2, and 10.0, respectively). Scores improved in the placebo-mavacamten group after switching to mavacamten (mean change week 30 to week 78: 7.3, 9.5, and 5.7, respectively). Similar improvements in KCCQ-23 physical limitations and quality-of-life scores with mavacamten were observed throughout both study periods. CONCLUSIONS: Long-term mavacamten treatment for up to 78 weeks led to sustained improvements in patient-reported health status, supporting long-term treatment with mavacamten for Chinese patients with symptomatic obstructive HCM. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT05174416.

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