A lthough low-density lipoprotein (LDL) is widely recognized as the major atherogenic lipoprotein and the primary target of lipid-lowering therapy, 1 other lipoprotein species nonetheless appear to be involved in atherogenesis. These include very low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), and highdensity lipoproteins (HDL). Both VLDL and IDL are triglyceride-rich lipoproteins (TGRLP). Thus, in the aftermath of unequivocal evidence that LDL lowering reduces risk for major coronary events and stroke, 2 the field of lipid study is turning more of its attention to the other lipoproteins that appear to be involved in atherosclerosis. The recent Adult Treatment Panel III (ATP III) report 1 of the National Cholesterol Education Program has summarized our current understanding of the relationship between other lipoprotein species and risk for coronary heart disease (CHD).
See p 2537ATP III 1 placed more emphasis on TGRLP and HDL as secondary targets of lipid-modifying therapy than did previous ATP reports. 3 There is an emerging consensus that among TGRLP, cholesterol-rich remnant lipoproteins carry atherogenic potential. This view led ATP III to designate LDL烯IDL烯VLDL cholesterol (called non-HDL cholesterol) as "atherogenic cholesterol" and to identify it as a secondary target of therapy, after LDL cholesterol. In the ATP III report, however, non-HDL cholesterol as a secondary target is limited to persons who have elevated serum triglyceride levels (諉200 mg/dL). In the majority of people who have lower triglyceride levels, LDL cholesterol contains the bulk of "atherogenic cholesterol" and thus is a sufficient target alone.The designation of elevated non-HDL cholesterol as a treatment target depended strongly on increasing data showing that high levels of cholesterol-rich TGRLP raise risk for CHD. Several reviews summarize the evidence for atherogenicity of triglyceride-rich remnants. 4 -6 On the other hand, only a limited number of studies 7,8 have examined the strength of association between non-HDL cholesterol and risk for CHD. The current report of Bittner et al 9 contributes to a growing body of information on the predictive power for major coronary events of non-HDL cholesterol. In the discussion to follow, the current status of non-HDL cholesterol as predictor of major coronary events and as a target of lipid-lowering therapy will be examined.
Predictive Power of LipoproteinsEpidemiological studies reveal a strong independent relation between serum cholesterol levels and risk for CHD. 10 Since LDL is the major cholesterol-carrying lipoprotein of serum, it too is widely accepted as an independent risk factor. 1 Prospective surveys 11 further document that reduced serum levels of HDL cholesterol independently predict CHD incidence. The case for high serum triglycerides as a marker for TGRLP has been less robust. 11 Since HDL cholesterol and triglycerides are inversely correlated, when HDL is entered into multivariate predictive models, triglycerides are generally found to be weak pr...