Background: While earlier studies indicated that cholesterol levels decrease significantly after an acute myocardial infarction (MI), a more recent study refuted this observation. 

Objectives: To assess changes in plasma lipid levels after onset of acute MI, and determine important predictors of lipid dynamics.

Methods: We prospectively measured lipid levels of patients who presented with an acute MI. Blood samples were drawn on admission to the hospital (day 1), after fasting at least 12 hours overnight (day 2), and on the 4th day of hospitalization (day 4). 

Results: Of 67 acute MI patients, 30 were admitted for ST elevation MI (STEMI) and 37 for non-STEMI. Both total cholesterol and low density lipoprotein cholesterol (LDL-C) levels decreased significantly (by 9%) in the 24 hours after admission and by 13% and 17% respectively on day 4. High density lipoprotein cholesterol (HDL-C) levels as well as triglycerides did not change significantly. Independent predictors of LDL-C decrease were the presence of diabetes mellitus [odds ratio (OR) 6.73, P = 0.01), and elevated cardiac troponin T (cTnT) levels (OR 1.81, P < 0.04).

Conclusions: LDL-C levels decrease significantly after an acute MI. The reduction is correlated with cTnT levels. Diabetes is a strong independent predictor of LDL-C decrease. In acute MI patients only measurements taken within 24 hours of onset should be used to guide selection of lipid-lowering medication.