Hypertrophic cardiomyopathy (HCM) is a genetic disease with delayed cardiac expression. Our objective was to characterize global and regional LV myocardial strain by two-dimensional imaging in sarcomeric HCM families and hypothesized that early systolic dysfunction, before hypertrophic stage, may be diagnosed by this technique. We analyzed 79 adults: HCM patients with LV hypertrophy (LVH+, n=38), mutation carriers without LV hypertrophy (LVH-/G+, n=20), and normal control subjects (n=21). We calculated global longitudinal strain (GLS) and regional peak longitudinal strain. Age, sex ratio and body surface area were not significantly different between groups. Maximal 2D wall thickness of left ventricle was 10.1±1.6 mm in LVH-/G+ and not different from controls (9.9 ±1.2 mm). We observed that LV GLS was not different in LVH-/G+ as compared to controls (–20.6% IQ:–24.2/– 8.3 vs –22.9% IQ:-26.8/-20.9) but was reduced in HCM patients (–14.1% IQ:–18.5/–11.8) although a normal ejection fraction. Interestingly, regional peak longitudinal strain was similar in LVH-/G+ and controls except in four segments: basal anteroseptal (BAS) wall (–16% vs –19%, p=0.018), basal inferoseptal wall (–16.0% vs –19.0%, p=0.047), basal inferior wall (–21.0% vs –24.0%, p=0.006) and mid anteroseptal wall (–21.0% vs –22.5%, p=0.022). Regional BAS strain <-16.5% yielded a sensitivity of 57% and a specificity of 90% to differentiate LVH-/G+ patients from controls. We also evaluated accuracy of ratio between normal and abnormal segments. Septo-basal/Latero-basal strain ratio <0.76 yielded a sensitivity of 73% and a specificity of 92% to differentiate LVH-/G+ patients from controls. Regional longitudinal strain but not global strain, was significantly reduced at early stage of HCM before development of LVH. This suggests the integration of myocardial deformation in the evaluation of HCM relatives to identify better mutation carriers and early LV abnormalities. The author hereby declares no conflict of interest