Cardiovascular disease remains the most pressing healthcare issue for developed countries and is becoming so for developing countries. There are a number of chronic therapies available for long-term management of risk. Short term therapies for subjects with an acute event, such as an episode of acute coronary syndrome (ACS), are focused on reperfusion and removing thrombus but most subsequent events are caused by atherosclerotic plaque rupture at a different site. There are no approved therapies that can rapidly reduce the burden of unstable, inflamed plaque in the overall coronary vascular bed. HDL has multiple actions that could lead to atherosclerotic plaque stabilization, such as rapid removal of large quantities of cholesterol from the vasculature, improvement in endothelial function, protection against oxidative damage and reduction in inflammation. This study will assess the effects of CER-001, an ApoA-I-based HDL mimetic, on indices of atherosclerotic plaque progression and regression as assessed by intravascular ultrasound (IVUS) measurements in patients with (ACS).