Low density lipoprotein (LDL) is the body’s primary cholesterol-carrying molecule, transporting cholesterol from the liver through the bloodstream to cells throughout the body. High blood levels of LDL cholesterol promote the development of coronary artery disease by contributing to the build-up of fatty plaques inside artery walls (atherosclerosis), which is why LDL is often called ‘bad cholesterol’.
When LDL particles accumulate in the artery wall, they trigger an inflammatory response. Over time, this leads to plaques that narrow the artery (stenosis) and can rupture, causing a blood clot that blocks the vessel and produces a heart attack or cardiac arrest. The relationship between LDL and cardiovascular risk is well established: for every 1 mmol/L reduction in LDL, the risk of a major cardiovascular event falls by approximately 20 to 25%.
Target LDL levels depend on individual cardiovascular risk. For very high-risk patients (such as those who have had a cardiac arrest or heart attack), NICE and ESC guidelines recommend an LDL below 1.4 mmol/L (or a reduction of at least 50% from baseline). These targets are achieved primarily with high-intensity statin therapy (such as atorvastatin 80mg), often supplemented with ezetimibe or, in very high-risk patients, PCSK9 inhibitors.
LDL is measured as part of a fasting lipid profile alongside total cholesterol, HDL cholesterol, and triglycerides. Regular monitoring is recommended after starting or adjusting lipid-lowering therapy to confirm targets are being met.
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