High Ischemic Risk Patients: Definition and Clinical Implications
Patients with atherosclerotic stroke should be considered at high ischemic risk, with an absolute 10-year risk of ≥20% for further atherosclerotic coronary events, similar to other established high-risk cardiovascular conditions. 1
Definition of High Ischemic Risk
High ischemic risk refers to patients who have an elevated absolute risk of experiencing future atherosclerotic cardiovascular disease (ASCVD) events. According to current guidelines, this is defined as:
Very High Risk Criteria
Patients are considered at very high risk if they have either:
- Multiple major ASCVD events, or
- One major ASCVD event plus multiple high-risk conditions 1
Major ASCVD Events Include:
- History of ischemic stroke
- Recent acute coronary syndrome (within past 12 months)
- History of myocardial infarction
- Symptomatic peripheral arterial disease 1
High-Risk Conditions Include:
- Age ≥65 years
- Heterozygous familial hypercholesterolemia
- History of coronary artery bypass surgery or percutaneous coronary intervention
- Diabetes
- Hypertension
- Chronic kidney disease
- Current smoking 1
Evidence Supporting High Risk Classification
The American Heart Association/American Stroke Association provides strong evidence that patients with atherosclerotic stroke have a high absolute risk of subsequent cardiovascular events, comparable to patients with established coronary heart disease:
- Patients with ischemic stroke have approximately 20% absolute risk over 10 years of fatal or nonfatal myocardial infarction or sudden death 1
- This risk level is similar to other conditions already recognized as coronary risk equivalents, such as diabetes mellitus and peripheral arterial disease 1
- The large-vessel atherosclerotic subtype of ischemic stroke shares pathophysiological mechanisms with other atherosclerotic disorders 1
Clinical Implications of High Ischemic Risk
Patients classified as high ischemic risk require more aggressive preventive interventions:
Lipid Management
- High-intensity statin therapy is recommended (atorvastatin 80 mg daily or rosuvastatin 20 mg daily) 1
- If LDL-C remains ≥70 mg/dL on maximally tolerated statin therapy, adding ezetimibe is recommended 1
- For very high-risk patients with LDL-C >70 mg/dL despite maximally tolerated statin and ezetimibe therapy, PCSK9 inhibitor therapy is reasonable 1
Antithrombotic Considerations
- Patients with prior stroke/TIA have an increased risk of both ischemic and hemorrhagic events 2
- The risk of hemorrhagic stroke is particularly high in the first year after stroke/TIA and in patients receiving dual antiplatelet therapy 2
- This requires careful balancing of antithrombotic therapy based on individual risk assessment
Polyvascular Disease and Risk Amplification
Patients with atherosclerosis in multiple vascular territories (polyvascular disease) represent an especially high-risk group:
- Each additional affected vascular territory increases the risk of major adverse cardiac events in a step-wise fashion 3
- Patients with ≥2 major ASCVD events have an event rate of 89.8 per 1,000 person-years compared to 41.3 for those with 1 event plus ≥2 high-risk conditions 4
- The age- and sex-adjusted hazard ratio for ASCVD events is 4.89 for patients with ≥2 major ASCVD events compared to those without very high risk 4
Important Clinical Considerations
Heterogeneity of stroke: While atherosclerotic stroke is clearly established as high risk, the evidence for non-atherosclerotic stroke subtypes is less certain 1
Dynamic risk profile: The risk of death for different atherosclerotic diseases changes over time, with PAD patients showing increasing mortality risk over follow-up that eventually approaches that of AMI and stroke patients 5
Sex differences: Case fatality rates differ between men and women, with women showing higher rates for both AMI (women: 20.9%, men: 12.7%) and ischemic stroke (women: 23.8%, men: 21.0%) 5
Monitoring: For patients with stroke/TIA and hyperlipidemia, adherence to lifestyle changes and effects of LDL-C-lowering medication should be assessed by measuring fasting lipids 4-12 weeks after statin initiation or dose adjustment and every 3-12 months thereafter 1
By recognizing patients at high ischemic risk and implementing appropriate preventive strategies, clinicians can significantly reduce the burden of recurrent cardiovascular events and improve patient outcomes.