This study aims to evaluate whether, under a treatment strategy primarily guided by left ventricular ejection fraction (LVEF), dose up-titration in adult patients with symptomatic obstructive hypertrophic cardiomyopathy who have received Mavacamten treatment for at least 12 weeks with a stable maintenance dose (as baseline) and with LVEF ≥55% can further reduce left ventricular outflow tract (LVOT) gradient after 24 weeks of treatment. It will also assess changes in hemodynamics, clinical symptoms, cardiac structure, and function. Furthermore, the study will conduct stratified analyses based on patients' baseline resting or Valsalva-provoked LVOT gradient levels at enrollment \[\<30 mmHg vs. ≥30 mmHg\] to explore differences in the aforementioned outcome measures among patients with different gradient levels, with the goal of providing evidence for individualized clinical dose adjustment.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
115
Eligible participants will undergo dose escalation at baseline from their current dose to the next higher level (once daily: 2.5 mg → 5 mg, 5 mg → 10 mg, or 10 mg → 15 mg). At Week 4, clinical status and echocardiography will be re-evaluated, and the same dose will be maintained for the subsequent 8 weeks, unless LVEF is \< 50%. After 12 weeks of treatment at the same dose level: If LVEF remains ≥ 55%, further dose escalation is permitted. If LVEF is between 50% and 55%, the current dose will be maintained. If LVEF is \< 50%, treatment will be interrupted/discontinued.
Change From Baseline in Valsalva Peak Left Ventricular Outflow Tract (LVOT) Pressure Gradient Assessed by Echocardiography at Week 24
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Left Ventricular Wall Thickness
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Left Atrial Volume Index
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Left Ventricular Mass Index
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS)
The Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS) includes the physical limitation and total symptom domains. Scores range from 0 to 100, where higher scores indicate better health status, fewer symptoms, and less physical limitation (a better outcome).
Time frame: Baseline and Week 24
Mitral Regurgitation Severity
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Systolic Anterior Motion
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
E/A Ratio
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Left Ventricular Ejection Fraction
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Left Atrial Volume Index
Time frame: Baseline and Week 24
Left Ventricular Wall Thickness
Time frame: Baseline and Week 24
New York Heart Association (NYHA) Functional Class
Assessed by the New York Heart Association (NYHA) Functional Classification. The classification categorizes heart failure severity into four classes: Class I (no limitation of physical activity), Class II (slight limitation), Class III (marked limitation), and Class IV (unable to carry on any physical activity without discomfort). Scores range from Class I to Class IV, where higher classes indicate worse heart failure symptoms (a worse outcome)
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
NT-proBNP
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
Myocardial troponin
Time frame: Baseline, Week 4, Week 8, Week 12, and Week 24
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