Screening patients with hypertrophic cardiomyopathy for Fabry disease using a filter-paper test: the FOCUS study

Abstract

Background Patients with Fabry disease (FD) show left ventricular hypertrophy (LVH) mimicking hypertrophic cardiomyopathy (HCM) of sarcomeric origin and might benefit, if detected early, from specific enzyme replacement therapy. The prevalence of FD in patients with LVH of 13 mm or greater, screened using the leucocyte alpha-galactosidase A (α-gal A) activity test, a technique that is difficult to apply routinely, ranged from 0% to 6%. Objective To screen systematically for FD in patients with a diagnosis of HCM (LVH ≥15 mm) in primary cardiology practice, a validated, physician-friendly α-gal A assay was used on dried blood spots using a filter paper test. Design and patients A cohort of 392 adults (278 men) followed for HCM were screened for FD. A standard blood test was used for confirmation in nine men in whom the α-gal A result was 40% or less. Results Four men (1.5%; 1.8% of men ≥40 years vs 0% Conclusion In male patients diagnosed as having HCM, pure FD cardiac variants are not exceptional and can be specifically identified using a simple filter-paper test. The sensitivity of this test is low in female patients.