Atherosclerosis is a pathology characterized by low-grade vascular inflammation rather than a mere accumulation of lipids. Inflammation is central at all stages of atherosclerosis. Acute coronary syndrome significantly affects the concentration and composition of the lipids and lipoproteins in plasma. Plasma triglyceride and very low density lipoprotein levels increase, while high density lipoprotein, low density lipoprotein and total cholesterol levels decrease. Early treatment of hyperlipidemia provides potential benefits. However, post-event changes in lipid and lipoproteins lead to delays in the choice of the treatment. This review focuses on the mechanism and the clinical importance of the relevant changes.