A 32-year-old patient complains of cardiac irregularities, dizziness, dyspnea at physical exertion. He has never suffered from such condition before. Objectively: Ps- 74/min., rhythmic. BP- 130/80 mm Hg. Auscultation revealed systolic murmur above aorta, the first heart sound was normal. ECG showed hypertrophy of the left ventricle, signs of repolarization disturbance in the I, V5 and V6 leads. Echocardiogram revealed that interventricular septum was 2 cm. What is the most probable diagnosis?