Hypertrophic cardiomyopathy is a complex cardiac disease with unique pathophysiologic characteristics and a great diversity of morphologic, functional, and clinical features.¹–⁸ The heterogeneity of the disease is accentuated by the fact that it afflicts patients of all ages. During the past few years, technological developments in implantable defibrillators and pacemakers have provided new therapeutic options for patients with the disease.⁹–¹⁸ In addition, rapid advances in our knowledge of the molecular defects responsible for hypertrophic cardiomyopathy have deepened our understanding of the disorder and have suggested new approaches to the assessment of prognosis.¹⁹–²² These recent developments, however, have . . .