LDL is called “bad” cholesterol because it can build up in the walls of your arteries and form plaque. Plaque build-up in the arteries can reduce blood flow and increase your risk of heart disease.
Because LDL particles can also transport cholesterol into the artery wall, retained there by arterial proteoglycans and attract macrophages that engulf the LDL particles and start the formation of plaques, increased levels are associated with atherosclerosis. Over time vulnerable plaques rupture, activate blood clotting and produce arterial stenosis, which if severe enough results in heart attack, stroke, and peripheral vascular disease symptoms and major debilitating events.
Increasing evidence has revealed that the concentration and size of the LDL particles more powerfully relates to the degree of atherosclerosis progression than the concentration of cholesterol contained within all the LDL particles. The healthiest pattern A, though relatively rare, is to have small numbers of large LDL particles and no small particles. Having small LDL particles, though common, is an unhealthy pattern B; high concentrations of small LDL particles (even though potentially carrying the same total cholesterol content as a low concentration of large particles) correlates with much faster growth of atheroma, progression of atherosclerosis and earlier and more severe cardiovascular disease events and death.
With all this said and done ultimately lowering your LDL does decrease your chance of cardiovascular disease (heart attack and stroke), but it doesn’t decrease your chance of dying from it if you haven’t had one before. From the last meta-analysis looking at over 65,000 patients without cardiovascular disease 1 out of every 60 patients treated with a statin (the most common cholesterol lowering drug class) had a non-fatal heart attack prevented, 1 out of every 268 patients treated with a statin had a stroke prevented, and no one had any mortality benefit. But there were far more adverse reactions with 1 in every 10 treated developing some form of muscle damage and 1 out of every 67 treated possibly developing diabetes. But in patients with known heart disease for every 83 treat 1 life was saved.
So we see a definite benefit for those with known heart disease, but what about everyone else. According to the ATP (Adult Treatment Panel) III guidelines:
It depends based on your risk of cardiovascular disease. We can develop your 10 year risk of a cardiovascular event based on the Framingham Risk Score. Based on this score and your LDL level drug therapy or lifestyle modification is recommended.
Overall guidelines alone are no replacement for clinical judgment, but in concert you and doctor should be able to make a treatment regimen that is evidence based and patient centered in your management of your LDL.