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A Comparative Study of the Effects of Selective Myosin Inhibitors Mavacamten and Cibenzoline on Exercise Tolerance in Patients with Obstructive Hypertrophic Cardiomyopathy

A Comparative Study of the Effects of Selective Myosin Inhibitors Mavacamten and Cibenzoline on Exercise Tolerance in Patients with Obstructive Hypertrophic Cardiomyopathy

Mizuno Yusuke

Hamamatsu University School of Medicine

1-20-1 Handayama, Chuo-ku, Hamamatsu city, Shizuoka, 431-3192, Japan

myusuke@hama-med.ac.jp

Mizuno Yusuke

Hamamatsu University School of Medicine

1-20-1 Handayama, Chuo-ku, Hamamatsu city, Shizuoka, 431-3192, Japan

+81-53-435-2111

myusuke@hama-med.ac.jp

Recruiting

April. 24, 2026

Interventional

single arm study

open(masking not used)

uncontrolled control

single assignment

treatment purpose

1. Patients aged 20 years or older
2. Patients with symptomatic obstructive hypertrophic cardiomyopathy (left ventricular maximum wall thickness >=15 mm, or >=13 mm with a family history, and left ventricular pressure gradient >=30 mmHg at rest or during exercise)
3. Patients with a baseline left ventricular ejection fraction (LVEF) >=55% on echocardiography
4. Patients taking sibenzoline for at least 2 weeks in addition to beta-blockers or calcium channel blockers at baseline
5. Individuals for whom consent for participation in this study was obtained via signed informed consent form by the subject or legal representative
6. Patients capable of undergoing cardiopulmonary exercise testing using a seated cycle ergometer

1. Patients with a history of drug hypersensitivity to macamute and for whom continued oral administration of macamute is considered difficult.
2. Patients with a history of syncope or sustained ventricular tachycardia during exertion within 6 months prior to screening.
3. Patients with a history of cardiac arrest or appropriate implantable cardioverter-defibrillator (ICD) activation within 6 months prior to screening.
4. Patients with persistent atrial fibrillation at screening who have not received anticoagulant therapy for at least 4 weeks or who have not achieved adequate rate control (heart rate > 110 beats/min).
5. Patients who underwent septal ablation therapy within 6 months prior to screening.
6. Patients with NYHA functional class IV.
7. Patients with Child-Pugh class C hepatic impairment.
8. Patients with symptomatic chronic obstructive pulmonary disease or symptomatic restrictive pulmonary disease.
9. Breastfeeding women.
10. Pregnant women or women who may be pregnant.
11. Patients presenting cardiac hypertrophy associated with the following conditions:
Hypertensive heart disease, valvular heart disease, congenital heart disease, ischemic heart disease, endocrine heart disease, anemia, cor pulmonale, patients with specific cardiomyopathies*
12. Other patients deemed inappropriate for study participation by the principal investigator (or co-investigator)

Both

Obstructive hypertrophic cardiomyopathy

In patients with obstructive hypertrophic cardiomyopathy, cardiopulmonary exercise testing will be performed before and after switching from sivenzolin to mavacamten to evaluate exercise tolerance.

mavacamten; cardiac myosin inhibitor; hypertrophic cardiomyopathy; obstructive hypertrophic cardiomyopathy; Cardiopulmonary exercise testing; Peak oxygen uptake

obstructive hypertrophic cardiomyopathy; mavacamten; cibenzoline; cardiopulmonary exercise testing; peak oxygen consumption; peak VO2; exercise tolerance; exercise capacity

D002312

C032151

Difference (change value) between peak VO2 measured during baseline cardiopulmonary exercise testing while taking sibenzoline and peak VO2 measured 40 weeks after switching to oral administration of mabacamten.

1. Change in pressure gradient across the left ventricular outflow tract during the Valsalva maneuver before and after mabacumten administration
2. Change in NT-pro BNP before and after mabacumten administration
3. Change in KCCQ-12 before and after mabacumten administration
4. Change in NYHA class before and after Mabacamten administration
5. Change in exercise tolerance indices from cardiopulmonary exercise testing: OUES (oxygen uptake efficiency slope), anaerobic threshold AT, VE vs. VCO2 slope, Max ETCO2, peak workload Peak WR, peak heart rate Peak HR, R (gas exchange ratio), oxygen uptake/work rate (aerobic capacity), peak VO2/HR, peak circulatory power, ventilatory power
6. Changes in grip strength and skeletal muscle index before and after Mabacamten administration
7. Correlation between baseline NT-pro BNP, left ventricular outflow tract pressure gradient, Hypertrophic Cardiomyopathy -Sudden Cardiac Death Risk model score, and peak VO2change
8. Safety evaluation items: Incidence of adverse events

+81-53-435-2680

April. 20, 2026

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