A 39 y.o. patient complains of having dyspnea during physical activity, crus edemata, palpitation, heart intermissions. Objectively: HR is 150 bpm, atrial fibrillation. Heart is both ways enlarged. Heart sounds are muted. Liver is 6 cm below the costal margin. Echocardiogram reveals dilatation of heart chambers (end diastolic volume of left ventricle is 6,8 cm) is 29% EF, valve apparatus is unchanged. What is the most probable diagnosis?