OJ-344 Comparison of Implantable Cardioverter-Defibrillators with Amiodarone Therapy in High-risk Japanese Patients with Poor Left Ventricular Function and Nonsustained Ventricular Tachycardia(Arrhythmia, therapy-5 (A) OJ58,Oral Presentation (Japanese),The 70th Anniversary Annual Scientific Meeting of the Japanese Circulation Society)