Summary: Very low levels of LDL cholesterol and triglycerides have been associated with a higher risk of hemorrhagic (bleeding) stroke in women.
Source: AAN
Lowering low-density lipoprotein (LDL) cholesterol is widely recommended to reduce the risk of heart attack and ischemic stroke, with an ideal level often cited as below 100 mg/dL. However, new research suggests that LDL levels that are very low—70 mg/dL or less—may be linked to an increased risk of hemorrhagic stroke in women. This study appears in the April 10, 2019 online issue of Neurology.
LDL cholesterol, commonly referred to as “bad” cholesterol, contributes to fatty deposits in arteries. The study also found that women with the lowest triglyceride levels—another type of blood fat—had a higher risk of hemorrhagic stroke compared with women who had the highest triglyceride levels.
Hemorrhagic strokes, caused by bleeding in or around the brain, are less common than ischemic strokes, which result from blocked blood flow. Bleeding strokes are often more difficult to treat and have a higher likelihood of being fatal.
“Lifestyle changes and medications such as statins are frequently used to lower cholesterol and triglyceride levels to prevent cardiovascular disease,” said Pamela Rist, ScD, of Brigham and Women’s Hospital in Boston and a member of the American Academy of Neurology. “Our large, long-term study indicates that very low LDL cholesterol and low triglycerides in women may carry some added risks. Since women face a higher overall stroke burden than men—partly because they tend to live longer—clarifying how best to manage these risks is essential.”
The prospective study followed 27,937 women aged 45 and older who participated in the Women’s Health Study. At enrollment, researchers measured total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol (the “good” cholesterol), and triglycerides. Investigators then confirmed strokes by reviewing medical records.
Over an average follow-up of 19 years, 137 women experienced a hemorrhagic stroke.
Among the subgroup with LDL cholesterol ≤70 mg/dL, 9 of 1,069 women (0.8 percent) had a hemorrhagic stroke. By comparison, 40 of 10,067 women (0.4 percent) whose LDL cholesterol ranged from 100 to 130 mg/dL had a hemorrhagic stroke. After adjustment for potential confounders—such as age, smoking, high blood pressure, and use of cholesterol-lowering medications—women with LDL ≤70 mg/dL were about 2.2 times as likely to suffer a hemorrhagic stroke as those in the 100–130 mg/dL group.
Triglyceride levels were analyzed in quartiles. The lowest group included fasting triglycerides ≤74 mg/dL (or non-fasting ≤85 mg/dL), while the highest group included fasting levels >156 mg/dL (or non-fasting >188 mg/dL). Among women in the lowest triglyceride quartile, 34 of 5,714 (0.6 percent) experienced a hemorrhagic stroke, compared with 29 of 7,989 (0.4 percent) in the highest quartile. After adjusting for other risk factors, those with the lowest triglycerides had approximately double the risk of hemorrhagic stroke relative to women with the highest levels.
No significant associations were observed between hemorrhagic stroke risk and total cholesterol or HDL cholesterol.
Rist emphasized clinical vigilance: “Women with very low LDL cholesterol or low triglycerides should be monitored for modifiable stroke risk factors—especially high blood pressure and smoking—to help reduce the likelihood of hemorrhagic stroke. Further research is needed to determine the best strategies for lowering hemorrhagic stroke risk in women with very low LDL and low triglycerides.”
The study has limitations. Lipid measurements were taken only once at baseline, so changes in cholesterol or triglyceride levels over time were not captured. In addition, many participants were already postmenopausal at baseline, limiting the study’s ability to assess whether menopausal status affects the relationship between lipid levels and hemorrhagic stroke.
Funding: The research was supported by the National Institutes of Health.
Source:
AAN
Media Contacts:
Renee Tessman – AAN
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The image is in the public domain.
Original Research (Closed Access):
“Lipid levels and the risk of hemorrhagic stroke among women” — Pamela M. Rist, Julie E. Buring, Paul M. Ridker, et al. Neurology. DOI: 10.1212/WNL.0000000000007454
Abstract
Lipid levels and the risk of hemorrhagic stroke among women
Objective: To evaluate the association between lipid levels and hemorrhagic stroke risk in women.
Methods: We conducted a prospective cohort study of 27,937 women in the Women’s Health Study with baseline measurements of total cholesterol, LDL-C, HDL-C, and triglycerides. Strokes were confirmed through medical record review. Cox proportional hazards models were used to estimate associations between lipid categories and hemorrhagic stroke risk.
Results: Over a mean follow-up of 19.3 years, 137 hemorrhagic strokes occurred. Compared with women whose LDL-C levels were 100–129.9 mg/dL, those with LDL-C <70 mg/dL had a multivariable-adjusted relative risk of 2.17 (95% CI 1.05–4.48) for hemorrhagic stroke. There were no significant increases in risk for LDL-C 70–99.9 mg/dL or 130–159.9 mg/dL; a non-significant trend toward increased risk was observed for LDL-C ≥160 mg/dL. Women in the lowest triglyceride quartile had a significantly higher risk of hemorrhagic stroke than those in the highest quartile (RR 2.00; 95% CI 1.18–3.39). Total cholesterol and HDL-C were not significantly associated with hemorrhagic stroke risk.
Conclusion: LDL-C levels below 70 mg/dL and low triglyceride concentrations were associated with an increased risk of hemorrhagic stroke among women.