This is a prospective, multi-center cohort study of patients with a history of coronary artery disease (CAD) and documentation of either a prior myocardial infarction (MI) or mild to moderate left ventricular dysfunction (LVEF 35-50%). The primary objective of this study is to determine whether biologic markers and ECGs can be utilized to advance SCD risk prediction in patients with CHD and LVEF>30-35%. The overarching goal of the study is to identify a series of markers that alone or in combination specifically predict risk of arrhythmic death as compared to other causes of mortality among this at risk population of coronary heart disease (CHD) patients with preserved left ventricular ejection fraction (LVEF> 30-35%). If biologic or ECG markers are identified that can specifically predict risk of ventricular arrhythmias, then these markers may serve as relatively inexpensive methods to identify those at risk. The public health impact of identifying markers could be quite substantial, leading to more efficient utilization of ICDs and advances in our understanding of mechanisms underlying SCD.