Background: Although studies have suggested that "late-onset" hypertrophic cardiomyopathy (HCM) may be caused by sarcomeric protein gene mutations, the cause of HCM in the majority of patients is unknown. This study determined the prevalence of a potentially treatable cause of hypertrophy, Anderson-Fabry disease, in a HCM referral population.
Methods and results: Plasma alpha-galactosidase A (alpha-Gal) was measured in 79 men with HCM who were diagnosed at > or =40 years of age (52.9+/-7.7 years; range, 40-71 years) and in 74 men who were diagnosed at <40 years (25.9+/-9.2 years; range, 8-39 years). Five patients (6.3%) with late-onset disease and 1 patient (1.4%) diagnosed at <40 years had low alpha-Gal activity. Of these 6 patients, 3 had angina, 4 were in New York Heart Association class 2, 5 had palpitations, and 2 had a history of syncope. Hypertrophy was concentric in 5 patients and asymmetric in 1 patient. One patient had left ventricular outflow tract obstruction. All patients with low alpha-Gal activity had alpha-Gal gene mutations.
Conclusion: Anderson-Fabry disease should be considered in all cases of unexplained hypertrophy. Its recognition is important given the advent of specific replacement enzyme therapy.