Hypertrophic cardiomyopathies (HCM) are caused in 30-60% of cases by mutations in cardiac sarcomere genes but can also be an expression of cardiac involvement in multi-systemic metabolic diseases, such as Anderson-Fabry disease (AFD). HCM entails a risk of sudden cardiac death (SCD) of 0.9%/year and is the most common cause of SCD in young adults. Recent studies suggested mechanical dispersion (MD) by speckle tracking echocardiography (STE) as an additional arrhythmic risk marker. The aim of the study was to evaluate left ventricle global longitudinal strain (LV-GLS) and MD, in patients with HCM or AFD cardiomyopathy, and the association with ventricular arrhythmias (V-AR). We evaluated 40 patients with HCM, 57 with AFD (12 with LV hypertrophy and 45 without), and 40 healthy subjects, between January 2014 and June 2022. We performed a comprehensive echocardiographic study and analysed systolic and diastolic functions, LV-GLS, and MD. We also analysed V-AR, including ventricular fibrillation and sustained/non-sustained ventricular tachycardia, by Holter electrocardiogram (Holter-EKG), in a subset of hypertrophic patients. Data were analysed by unpaired Student t-test or chi-square/Fisher's exact test as appropriate and binary logistic regression (SPSS Statistics ver.26). LV-GLS was significantly lower in the V-AR group compared with patients without V-AR (median -10.2% vs. -14%, P = 0.038); MD was significantly higher in the V-AR group (85.5 ms vs. 61.1 ms, P = 0.004). V-AR were found significantly associated with MD (OR, 1.030; 95% CI, 1.003-1.058; P = 0.03). MD is a useful additional index in the evaluation of patients with HCM and may be a promising prognostic predictor of increased arrhythmic risk.