SCD is a death due to some cardiac causes. The heart damage reflected by the LVEF and loss of cardiac reserve and prognosis of patients with structural heart disease are discussed. Ongoing trails are MADIT II, SCD-HeFT and ICD. Electrocardiographic measures describe electrocardiogram markers which includes intraventricular conduction delay, left ventricular hypertrophy, late potentials and fragmented QRS complexes. Autonomic nervous system abnormalities influence the risk of malignant ventricular arrhythmias or sudden death. The measurement of HRV, HRT and determination of baroreceptor sensitivity. Repolarization abnormalities are based on MPIP study includes QT interval, variability, dispersion, microvolt electrical alternans and early repolarization syndrome. Current guidelines in management and prevention of sudden cardiac death under patient medications, family history, drug use and risk factors. The challenge for research in risk is to focus on the purpose and process of risk stratification to improve discrimination of high risk versus those at low risk for SCD.