Mavacamten

The KCCQ-23 is a 23-item, self-administered questionnaire that measures the impact of a participant's cardiovascular disease or its treatment on 6 distinct domains using a 2-week recall period: symptoms/signs, physical limitation, quality of life (QoL), social limitations, self-efficacy, and symptom stability. The KCCQ 23 Clinical Summary Score (CSS) is derived from the Total Symptom Score (TSS) and the Physical Limitations (PL) score of the KCCQ 23. The CSS, TSS, and the PL score range from 0 to 100 with higher scores representing less severe symptoms and/or physical limitations. The CSS is a mean of the TSS and the PL score. Baseline is defined as the last non-missing assessment prior to the first dose of the study treatment if both the time of the measurement and the time of first dose are available otherwise it is the last non-missing assessment on or prior to the first dose of the study treatment.

Clinically meaningful mean change from baseline(1.4ml/kg/min) of pVO2 at Week 48.

The post-exercise LVOT gradient was measured from echocardiograms obtained at baseline and week 30 following a study-specified exercise protocol and read by the doppler echocardiography. Baseline is defined as the last non-missing assessment prior to the first dose of the study treatment if both the time of the measurement and the time of first dose are available otherwise it is the last non-missing assessment on or prior to the first dose of the study treatment.

Participants who decided to proceed with SRT or were eligible for SRT at week 16. Participants with missing assessments were classified as meeting the primary endpoint (did not improve). SRT eligibility using the New York Heart Association Functional Class (NYHA) and left ventricular outflow tract (LVOT) assessments per the 2011 ACCF/AHA guideline clinical and hemodynamic criterion are below: * NYHA Class III or IV/ NYHA Class II with exertion-induced syncope/near syncope, AND * Dynamic LVOT gradient at rest or with provocation \>= 50 mmHg. NYHA Class II at week 16, the following rules will be applied: * NYHA Class II with history of exertional syncope/ syncope at baseline and at W16 is still NYHA Class II, they remain SRT eligible IF their maximal LVOT gradient is ≥ 50mmHg * NYHA Class III/IV at baseline and at W16 has improved to Class II, they are no longer SRT eligible UNLESS they have AE of exertional syncope or pre-syncope during the 16 weeks.

A positive clinical response (value="YES") is defined as having achieved either an improvement of at least 1.5 mL/kg/min in peak oxygen consumption (pVO2) as determined by cardiopulmonary exercise testing (CPET) and a reduction of one or more class in New York Heart Association (NYHA) functional classification (e.g.I, II, III, or IV) -OR- an improvement of 3.0 mL/kg/min or more in pVO2 with no worsening in NYHA Functional Class.

Treatment-emergent Adverse event (TEAE) is defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product; it does not necessarily have to have a causal relationship with this treatment.

Adverse event (AE) is defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product; it does not necessarily have to have a causal relationship with this treatment. AEs of special interest include: Symptomatic overdose, teratogenicity, and LVEF ≤30%

Treatment-emergent serious adverse event (TESAE) is defined as any untoward medical occurrence at any dose that: Results in death, Is immediately life-threatening (places the participant at immediate risk of death from the event as it occurred), Requires inpatient hospitalization or prolongation of existing hospitalization, Results in persistent or significant disability or incapacity or substantial disruption of the ability to conduct normal life functions, Results in a congenital abnormality or birth defect, Is an important medical event that may not result in death, be life-threatening, or require hospitalization, but may be considered an SAE when, based upon appropriate medical judgment, it may require medical or surgical intervention to prevent any of the outcomes listed above.

Blood samples were collected to assess the abnormalities in laboratory parameters.

Treatment-emergent Adverse event (TEAE) is defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product; it does not necessarily have to have a causal relationship with this treatment.

Treatment-emergent Adverse event (TEAE) is defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product; it does not necessarily have to have a causal relationship with this treatment.

Ratio to baseline in N-terminal pro B-type natriuretic peptide levels. The baseline value is defined as the last available value before the first administration of study drug.

Ratio to Baseline in resting high sensitivity cardiac troponin T (hs-cTnT) levels. The baseline value is defined as the last available value before the first administration of study drug.

AE is defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product; it does not necessarily have to have a causal relationship with this treatment. An SAE is defined as any untoward medical occurrence at any dose that: * Results in death * Is immediately life-threatening (places the participant at immediate risk of death from the event as it occurred) * Requires inpatient hospitalization or prolongation of existing hospitalization * Results in persistent or significant disability or incapacity or substantial disruption of the ability to conduct normal life functions * Results in a congenital abnormality or birth defect * Is an important medical event that may not result in death, be life- threatening, or require hospitalization, but may be considered an SAE when, based upon appropriate medical judgment, it may require medical or surgical intervention to prevent any of the outcomes listed above.

Number of participants who had died due to cardiovascular reasons.

Number of participants who experienced sudden death

Number of participants who were hospitalized for cardiovascular reasons.

Number of participants with heart failure due to systolic dysfunction, defined as asymptomatic LVEF \< 50%

Number of participants with LVEF \< 50% as measured by echocardiography.

Number of participants who experienced myocardial infarction.

Types of Ventricular Arrhythmias measured in this endpoint will be: Ventricular Tachycardia Ventricular Fibrilation Ventricular Flutter

Number of participants who experienced syncope. Syncope will be defined as participants who experienced dizziness or orthostatic hypotension.

Number of participants who were experienced seizures.

Number of participants who were experienced strokes.

Number of participants with a change in QTcF intervals. QTcF: An electrocardiographic finding in which the QT interval corrected for heart rate using Fridericia's formula. QTc = QT/∛(RR/1000) RR = Respiration rate QT Interval: Ventricular depolarization plus ventricular repolarization Normal Range: 400 to 460 msec

Number of participants with changes of Post-exercise left ventricular outflow tract (LVOT) gradient over time

Resting left ventricular outflow tract (LVOT) gradient over time

Post Valsalva left ventricular outflow tract (LVOT) gradient over time

Participants with \>= 1 NYHA function class improvement. The NYHA Functional Classification of heart failure assigns participants to 1 of 4 categories based on the participant's symptoms. Class 1: No limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea (shortness of breath). Class 2: Slight limitation of physical activity. Comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea (shortness of breath). Class 3: Marked limitation of physical activity. Comfortable at rest. Less than ordinary activity causes fatigue, palpitation, or dyspnea. Class 4: Unable to carry on any physical activity without discomfort. Symptoms of heart failure at rest. If any physical activity is undertaken, discomfort increases.

The Kansas City Cardiomyopathy Questionnaire (KCCQ) is a self-administered 23-item questionnaire questionnaire that measure the participant's perception of their health status, including their heart failure (HF) symptoms, impact on physical and social function and how their HF impacts the quality of life. KCCQ quantifies 7 domains: physical limitations (6 items), symptom stability (1 item), symptom frequency (4 items), symptom burden (3 items), self-efficacy (2 items), quality of life (3 items) and social limitations (4 items). Scores were generated for each domain and scaled from 0 to 100, with 0 denoting the worst and 100 the best possible status. Overall KCCQ Pro score is the average of all the domains, symptom frequency and symptom burden scores, and transformed to a single score which ranged from 0 (worst) to 100 (the best possible status), where the higher score reflected better health status.

Mean change from baseline in Serum N-terminal pro B-type natriuretic peptide levels.

Number of participants who received septal reduction therapy

Plasma concentration of Mavacamen overtime

This is the percentage of participants who experienced at least one treatment emergent adverse event (TEAE)

This is the percentage of participants who experienced at least one serious treatment-emergent adverse event (STEAE)