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| LDL not always the best predictor of stroke risk |
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March 2008
Elevated levels of serum triglycerides and non–high-density lipoprotein (HDL) have been associated with an increased risk of large artery atherosclerotic (LAA) stroke, suggesting that low-density lipoprotein (LDL) may not always be the best predictor of atherosclerotic vascular risk.
LDL cholesterol is the primary lipid target for vascular risk reduction in stroke patients, but emerging data suggest that other lipid indices may better predict vascular hazard. A new study evaluated the relationship between several measures of the classically obtained serum lipid panel and the occurrence of large artery atherosclerotic stroke.
Data prospectively collected over 4 years in subjects admitted with ischaemic stroke or TIA to a university medical centre were analysed. Independent associations between fasting serum lipid indices and LAA stroke mechanisms were evaluated.
The study showed that people with the highest triglyceride level are 2.7 times more likely to suffer LAA, while those with the highest non-HDL levels had a 2.4-fold increased risk of large artery stroke.
The study enrolled 1,049 patients of whom 247 (23.5%) were classified with LAA, 224 (21.4%) were classified with small vessel disease (SVD), and 578 (55%) were non-LAA-, non-SVD-subtype. Lipid levels were similar between LAA and SVD patients.
Total cholesterol, triglycerides, LDL, non-HDL cholesterol, and the triglyceride/HDL ratio were significantly higher in LAA vs non-LAA, non-SVD patients. After adjustment for age, hypertension, diabetes, smoking, body mass index, and premorbid statin use, significant odds ratios (ORs) for LAA compared with all other ischaemic stroke subtypes for patients in the uppermost lipid quartiles (vs lowest) were triglycerides (OR 2.69, 95% CI 1.44 to 5.02) and non-HDL (OR 2.39, 95% CI 1.40 to 4.11). LDL was not associated with LAA.
"LDL has been the primary target for reducing the risk of stroke, but these results show other types of cholesterol may be more strongly linked with stroke risk," said principal investigator Bruce Ovbiagele MD.
"Our data indicate that other traditional serum lipid measures such as the triglyceride level, as well as less commonly assessed indices derived from the routinely ordered serum lipid panel such as non-HDL cholesterol, may be more strongly associated with symptomatic large artery cervicocephalic atherosclerosis (vs all other ischaemic stroke subtypes) than the LDL level", the authors write.
According to the authors, there is conflicting evidence with respect to the importance of circulating serum lipids in stroke, with some early studies reporting no association between stroke risk and elevated cholesterol. However, they note, this research generally did not distinguish between stroke subtype or lipid subfractions.
More recent studies have demonstrated an association between serum cholesterol levels and ischaemic stroke, but few have examined the relationship between serum lipids and subtype of ischaemic stroke most directly linked to lipid metabolism.
"This may be important in the light of evidence that the effect of plasma lipids on atherogenesis in the cerebrovascular bed may be distinct from that in the coronary vascular bed," they write. Furthermore, they point out that current national US guidelines, which emphasise the management of LDL cholesterol, are largely based on evidence from the cardiac literature.
However, they note, "there is mounting evidence that other serum lipid indices derived from the classic lipid profile may be better predictors of vascular risk than LDL."
Compared with all other ischaemic stroke subtypes, elevated levels of serum triglycerides and non-HDL, but not LDL, are associated with large artery atherosclerotic stroke. These non-LDL lipid measures may be useful in delineating atherosclerotic stroke risk.
In the light of these findings, the authors suggest, clinicians may want to consider focusing additional attention on other aspects of the lipid panel when treating patients with or at risk for atherosclerotic stroke. However, they note, LDL and its role in patients' overall health should not be discounted.
The study was published entitled "Association of serum lipid indices with large artery atherosclerotic stroke" in the December issue of Neurology.
Reference:
Bang et al. Neurology 2008, 70:841-47
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