Cholesterol measurement following myocardial infarction

• lipid levels (total, LDL and HDL cholesterol) fall significantly about 24 hours after an acute myocardial infarction and remain reduced for, in general, at least 6 weeks - therefore measurements taken during this period produce unrepresentatively low results (1)
  • at the time of an acute coronary syndrome, particularly myocardial infarction, total cholesterol, LDL cholesterol, and HDL cholesterol decrease (and triglycerides may rise)
• similar effects on blood lipids may result from other acute vascular diseases, other severe diseases, and major surgery
  • the reduction in levels of total cholesterol following myocardial infarction generally lasts for about 6-8 weeks, however reduction in level can be longer if there is a complicated recovery
  • lipid measurement should be undertaken as soon as possible after onset of acute coronary syndrome (and preferably within 24 hours of the onset of symptoms). Measurement will provide a reasonable indication of the total cholesterol and HDL cholesterol values before the acute event, although it will generally be an underestimate
  • in light of the reduction of lipid levels following acute coronary syndrome, it is important to measure a full fasting lipoprotein profile about 8-12 weeks following the acute event, although this will usually be after statin treatment has been started. Reasons for rechecking lipid levels include
    • assessment to whether the person has achieved the total and LDL cholesterol targets and hence a guide to possible changes in lipid modification therapy
    • secondary causes of elevated lipids, where these have not already been fully investigated during the hospital admission, should be assessed at the same time (include alcohol abuse, diabetes, renal disease, liver disease, and inadequately treated hypothyroidism)

Reference:

1. Factfile (6/98). British Heart Foundation.
2. JBS2: Joint British Societies' guidelines on prevention of cardiovascular disease in clinical practice. Heart 2005; 91 (Supp 5).