The endocardial binary appearance ('binary sign') is an unreliable marker for echocardiographic detection of Fabry disease in patients with left ventricular hypertrophy.

ABSTRACT

AIMS: The binary sign, a binary appearance of the left ventricular endocardial border, was suggested to be an echocardiographic hallmark in diagnosing Fabry disease, a hereditary, lysosomal storage disorder. The aim of the present study was to examine the reliability of the binary sign as a screening tool to identify patients with Fabry disease. METHODS AND RESULTS: In total 309 subjects with an interventricular septum (IVS) thickness of ≥12 mm were investigated, of which 14 had a confirmed diagnosis of Fabry disease. Urinary globotriaosylceramide testing was used to rule out Fabry disease in the control group. From all patients echocardiographic images of the apical four-chamber view were analysed offline by a blinded observer. A binary sign was seen in 63 patients (20%), 4 had Fabry disease and 59 belonged to the control group. Although the proportion of binary signs in patients with Fabry disease was higher (29%) compared with the control group (20%) this difference was not statistically significant. The sensitivity and specificity were 28% (95% confidence interval (CI) 12-65%) and 80% (95% CI 76-85%), respectively. In a logistic regression model adjusted for age, sex and presence of Fabry disease, the occurrence of a binary sign was highly dependent on the IVS thickness (odds ratio 1.21; 95% CI 1.1-1.35; P<0.001). CONCLUSION: The endocardial binary appearance is associated with the degree of septal hypertrophy but cannot adequately distinguish between patients with Fabry disease and patients with other causes of left ventricular hypertrophy.