This study is testing a drug called mavacamten for teenagers with a heart condition called symptomatic obstructive hypertrophic cardiomyopathy (HCM). HCM is when the heart muscle becomes thick and makes it hard for blood to flow. The study will check if the drug works well, is safe, and how it moves in the body. To join, you need to have HCM, a blockage in your heart's blood flow, and symptoms like shortness of breath. You can't join if you have other heart issues, a weak heart muscle (less than 50% pumping ability), or plan for major heart treatment soon. The study will last a few months, and you might have to visit the clinic for check-ups. Participants may receive compensation for their time and travel. Remember, it's important to talk with your doctor and family to decide if this study is right for you.

• Study involves several clinic visits.
• Participants may receive compensation.
• Discuss with your doctor before joining.