A. SPECIFIC AIMS Sudden and unexpected cardiac death remains a significant problem in patients with established coronary heart disease (CHD), and accounts for 30% of deaths in this group (~150,000 deaths annually) despite recognition and treatment of their disease. These sudden deaths are due to myocardial infarction and ischemic or nonischemically mediated arrythmias. Traditional risk factors do not completely account for the excess of CHD deaths. Although treatment of cardiac risk factors, such as hyperlipidemia, has been shown to significantly reduce cardiac events in populations with established coronary heart disease (e.g. by 34% in the Scandinavian Simvastatin Survival Study1) a majority of patients continue to have sudden and unexpected cardiac events including sudden cardiac death. Indeed, up to 50% of patients with established CHD will have recurrent events despite aggressive management of traditional risk factors such as hyperlipidemia, tobacco use and hypertension. This suggests that additional risk factors or mechanisms participate in the pathophysiological cascade underlying acute CHD events.