Triglycerides are the Least Worrisome Lipid Parameter for Stroke and MI Risk
Among total cholesterol, triglycerides, and LDL cholesterol, triglycerides are the least directly implicated in increasing the risk of stroke and myocardial infarction (MI).
Evidence on Lipid Parameters and Cardiovascular Risk
LDL Cholesterol: Strongest Association with Cardiovascular Events
- LDL cholesterol shows the strongest causal relationship with atherosclerotic cardiovascular disease
- Meta-analyses demonstrate that every 1.0 mmol/L reduction in LDL cholesterol is associated with a 20-25% reduction in cardiovascular disease mortality and non-fatal myocardial infarction 1
- Treatment-related decreases in LDL cholesterol are associated with decreases in all strokes (4.5% risk reduction per 10-mg/dL reduction) 1
- The risk of myocardial infarction increases by 34% per 1.0 mmol/L increase in LDL cholesterol, with particularly strong effects in older adults 2
Total Cholesterol: Significant Impact on Cardiovascular Risk
- Reduction in stroke risk is proportional to reduction in total cholesterol; each 1% reduction in total cholesterol is associated with a 0.8% reduction in stroke risk 1
- Total cholesterol is incorporated into cardiovascular risk calculators along with other factors such as age, sex, race, blood pressure, and diabetes 1
- High total cholesterol is predictive of future coronary heart disease events 3
Triglycerides: Weakest Independent Association
- Meta-analyses show no significant relationship between triglycerides and stroke risk 1
- While triglycerides may have some association with cardiovascular events, they have not demonstrated the same strength of association as LDL-C and total cholesterol 1
- In a meta-analysis of 64 randomized controlled trials, there was no relationship between triglycerides and stroke, while LDL-C showed a clear association 1
Clinical Implications for Risk Assessment and Management
Risk Assessment
- Current guidelines focus primarily on LDL cholesterol as the main target for lipid-lowering therapy 1
- The American Heart Association/American Stroke Association guidelines recommend statin therapy to achieve LDL cholesterol targets for stroke prevention 1
- Canadian Stroke Best Practice Recommendations suggest targeting LDL cholesterol to less than 2.0 mmol/L or >50% reduction from baseline 1
Treatment Priorities
- Statins are the primary lipid-lowering therapy with proven benefits for reducing stroke and MI risk 1
- The benefits of other lipid-modifying therapies (fibrates, diet alone) on stroke risk are not as well established as statins 1
- For secondary prevention in patients with ischemic stroke or TIA, statins should be prescribed to achieve target LDL cholesterol levels 1
Important Caveats and Considerations
- While triglycerides show the weakest association with stroke and MI among the three lipid parameters, elevated triglycerides may still contribute to cardiovascular risk, particularly in younger adults 4
- In some specific populations, such as young adults (20-39 years), triglycerides may have a stronger independent association with clinical events 4
- The relationship between lipids and hemorrhagic stroke differs from ischemic stroke, with some studies showing an inverse relationship between cholesterol levels and risk of hemorrhagic stroke 1
- Lipid management should be part of a comprehensive approach to cardiovascular risk reduction that includes addressing other modifiable risk factors
Clinical Decision Algorithm
- Prioritize LDL-C assessment and management as the primary lipid target
- Use total cholesterol as an important secondary target
- Consider triglycerides as a tertiary concern, particularly in patients with normal LDL-C and total cholesterol
- For patients with established cardiovascular disease or at high risk:
- Target LDL-C <2.0 mmol/L or >50% reduction from baseline
- Consider more aggressive targets (LDL-C <1.8 mmol/L) for those with stroke and coronary disease
In summary, while all three lipid parameters contribute to cardiovascular risk, the evidence most strongly supports LDL cholesterol as the primary driver of atherosclerotic cardiovascular disease, followed by total cholesterol, with triglycerides showing the weakest independent association with stroke and MI risk.