Patients will be randomly assigned in 1:1 ratio either to candesartan (target dose 32 mg once daily) or matching placebo. The initial dose of the study drug will be 8 mg once daily. Study drug dose will be then doubled as tolerated every 2 weeks while aiming for a target dose of 32 mg once daily. Monitoring of blood pressure, serum creatinine, serum potassium and pressure gradient in LV outflow tract will be performed during dose increase. Patients will be observed clinically at 3, 6, and 12 months after the maintenance dose was reached. Exercise tolerance will be assessed by bicycle ergometry, presence of malignant arrhythmias by Holter monitoring, extent of LV hypertrophy by 2-dimensional echocardiography, and LV outflow tract pressure gradient by Doppler echocardiography at baseline and 12-month follow-up.