Figure 4 :(a) M-mode of mitral valve before beta-blocker therapy: There is systolic anterior motion of the mitral valve (SAM) with contact with the interventricular septum, lasting about 40% of systole, suggesting significant LVOT obstruction. Fig.4b: M-mode of mitral valve after beta-blocker therapy: There is systolic anterior motion of the mitral valve (SAM) but there is no contact with the interventricular septum suggesting decrease in LVOT obstruction.