Patients with hypertrophic cardiomyopathy and symptoms without severe outflow obstruction will be eligible to participate. Enrollment will be limited to subjects who are unable to attain 75% of their maximum predicted MVO2 at cardiopulmonary exercise testing. Subjects with genetic evidence of CYP2D6 poor metabolizer status will be excluded.
Subjects will undergo functional testing at baseline with CPEX testing and 6 minute walk distance testing. They will begin perhexiline orally, and the dose will be adjusted according to plasma level testing. For the first 8 week period, the target therapeutic range will be 100-300 ng/mL, and for the second 8 week period, the range will be 300-500 ng/mL. Functional testing will be repeated at the end of both periods.
