A total of 1116 patients with left ventricular (LV) dysfunction following the first episode of acute ST-elevation MI are to be enrolled and randomized to maximal tolerable dose (up to 320 mg/day) or usual dose (80 mg/day) of valsartan for 12 months in 2:1 ratio. Echocardiographic analysis for quantifying post-MI ventricular remodeling and genotyping of blood samples are conducted in central core laboratory. Clinical assessment and laboratory test are performed at fixed times, and genetic polymorphisms of the patients are tested at the time of admission.