To evaluate the safety of mavacamten in patients with symptomatic obstructive hypertrophic cardiomyopathy (obstructive HCM) in the real-world setting. The registry evaluates patient characteristics, real-world treatment patterns and short- and long-term outcomes in a population of patients with symptomatic obstructive HCM who are receiving mavacamten, receiving other treatment for obstructive HCM, or not receiving treatment for obstructive HCM due to intolerance or failure of prior treatment.