HCM patient with fibrosis in the interventricular septum, pronounced mechanical dispersion by strain echocardiography and ventricular arrhythmia. This HCM study patient was hospitalized because of heart failure symptoms. LGE-CMR detected fibrosis in the interventricular septum (white vertical arrow) with 23% LGE (upper panel). ECG monitoring showed nsVT with rate 150 bpm (mid panel). Mechanical dispersion was pronounced at 100 ms (lower panel). Mechanical dispersion was calculated as SD of time from Q/R on ECG to peak negative longitudinal strain in 16 LV segments. Grey scale ≥5 SD above normal myocardium was defined as LGE by CMR.