Slide 33 -
Inflammation and CHD Nathan Wong
Thrombosis, Inflammation, and Infection Many persons experiencing cardiovascular events often do not have well-recognized standard risk factors such as elevated cholesterol or hypertension.
Thrombosis, local or systemic inflammation, and chronic infection may play important roles in the initiation and progression of CHD Beyond Cholesterol: Predicting Cardiovascular Risk In the 21st Century Cardiovascular Risk Lipids HTN Diabetes Behavioral Hemostatic Thrombotic Inflammatory Genetic Total Cholesterol Distribution: CHD vs Non-CHD Population 35% of CHD Occurs in People with TC<200 mg/dL 150 200 Total Cholesterol (mg/dL) 250 300 No CHD CHD Framingham Heart Study—26-Year Follow-up Inflammation and Atherosclerosis Inflammation may determine plaque stability
- Unstable plaques have increased leukocytic infiltrates
- T cells, macrophages predominate rupture sites
- Cytokines and metalloproteinases influence both stability and degradation of the fibrous cap
Lipid lowering may reduce plaque inflammation
- Decreased macrophage number
- Decreased expression of collagenolytic enzymes (MMP-1)
- Increased interstitial collagen
- Decreased expression of E-selectin
- Reduced calcium deposition Is there clinical evidence that inflammatory markers predict future coronary events and provide additional predictive information beyond traditional risk factors? Evaluating Novel Risk Factors for CAD Consistency of prospective data
Strength of association
Independence of association
Improve predictive value
Standardized measure Low variability
Modifiable Biomarkers for Venous and Arterial Thrombosis +++ – hs-CRP / SAA / IL-6 / TNF + – Lp(a) ++ – Platelet function ++ – PAI-1: ag +++ – tPA: ag ++ – vWF: ag + – Factor VII +++ – Fibrinogen Arterial Venous Parameter Biomarkers for Venous and Arterial Thrombosis (cont’d) ++ ++ D-dimer ++ ++ Homocysteine – + Protein S – + Protein C – ++ Anti-thrombin III – ++ Factor VIII – + Prothrombin – ++ Prothrombin mutation – +++ Factor V Leiden Arterial Venous Parameter Thrombosis and Cardiovascular Risk Thrombus formation is a crucial factor in the precipitation of unstable angina or myocardial infarction, as well as occlusion during or following angioplasty.
Often preceded by platelet aggregation and activation of the coagulation system.
A thrombus may develop at sites of only mild to moderate coronary stenosis. The majority of coronary events occur where there is less than 70% stenosis.
Occlusive coronary thrombosis plays a role in over 80% of myocardial infarctions and about 95% of sudden death victims. Fibrinogen and Atherosclerosis Promotes atherosclerosis
Essential component of platelet aggregation
Relates to fibrin deposited and the size of the clot
Increases plasma viscosity
May also have a proinflammatory role
Measurement of fibrinogen, incl. Test variability, remains difficult.
No known therapies to selectively lower fibrinogen levels in order to test efficacy in CHD risk reduction via clinical trials. Fibrinogen and CHD Risk: Epidemiologic Studies Recent meta-analysis of 18 studies involving 4018 CHD cases showed a relative risk of CHD of 1.8 (95% CI 1.6-2.0) comparing the highest vs lowest tertile of fibrinogen levels (mean .35 vs. .25 g/dL)
ARIC study in 14,477 adults aged 45-64 showed relative risks of 1.8 in men and 1.5 in women, attenuated to 1.5 and 1.2 after risk factor adjustment.
Scottish Heart Health Study of 5095 men and 4860 women showed fibrinogen to be an independent risk factor for new events--RRs 2.2-3.4 for coronary death and all-cause mortality. Fibrinogen and CHD Risk Factors Fibrinogen levels increase with age and body mass index, and higher cholesterol levels
Smoking can reversibly elevated fibrinogen levels, and cessation of smoking can lower fibrinogen.
Those who exercise, eat vegetarian diets, and consume alcohol have lower levels. Exercise may also lower fibrinogen and plasma viscosity.
Studies also show statin-fibrate combinations (simvastatin-ciprofibrate) and estrogen therapy to lower fibrinogen.
Other Thrombotic Factors and CHD Mixed reports of coagulation factor VIIc in cardiovascular disease. PROCAM study showed no association with CHD events, CHS also showed no relation to subclinical CVD.
Endogenous tissue-type plasminogen activator (tPA) shown in some studies to relate to increased cardiovascular risk--Physician’s Health Study showed RR for MI 2.8, stroke 3.5 in those in 5th vs. 1st quintile of tPA.
Plasminogen activitor inhibitor type 1 (PAI-1) shown associated with increased cardiovascular risk, esp in diabetic patients. Aspirin and Cardiovascular Risk: Clinical Trial Evidence for Primary Prevention US Physician’s Health Study- 22,071 male physicians - 44% reduction in MI risk, 13% nonsignificant increase in risk of stroke
British Doctor’s Study of 5139 male physicians showed nonsignificant 3% reduction in MI risk,13% nonsignificant increase in stroke
Hypertension Optimal Treatment (HOT) study among 18,790 pts w/htn showed 15% reduction in CVD events, 36% reduction in MI
Ongoing Women’s Health Study (n=40,000) Aspirin and Cardiovascular Risk: Clinical Trial Evidence for Secondary Prevention Antiplatelet Trialists Collaboration of 54,000 patients with cardiovascular disease (10 trials post-MI) showed 31% reduction in MI, 42% reduction in stroke, 13% reduction in total vascular mortality
International Study of Infarct Survival of 17,187 pts w/evolving MI showed 49% reduction in reinfarction, 26% reduction in nonfatal stroke, and 23% reduction in total vascular mortality Antiplatelet Therapy: AHA Recommendations Aspirin is clearly recommended in secondary prevention. Provides additional benefit in conjunction with thrombolytic therapy. Clopidogrel may be an option in aspirin-intolerant patients.
Aspirin is not recommended for primary prevention in those free of CHD and younger than 50 years old.
Aspirin may be considered in those over age 50 with additional risk factors, free of contraindications, and may benefit those with hypertension, diabetes, and cigarette smoking.
American Diabetes Association recommends aspirin in diabetics with at least one other CHD risk factor. Relative Risks of Future MI among Apparently Healthy Middle-Aged Men: Physician’s Health Study Relative Risk for Future MI 0 1.0 2.0 4.0 6.0 Lipoprotein(a) Homocysteine Fibrinogen tPA Antigen hs-CRP hs-CRP + TC/HDL-C Total Cholesterol TC:HDL-C Risk Factors for Future Cardiovascular Events: WHS Relative Risk of Future Cardiovascular Events 0 Lipoprotein(a)
hs-CRP + TC:HDL-C 1.0 2.0 4.0 6.0 CRP vs hs-CRP CRP is an acute-phase protein produced by the liver in response to cytokine production (IL-6, IL-1, tumor necrosis factor) during tissue injury, inflammation, or infection.
Standard CRP tests determine levels which are increased up to 1,000-fold in response to infection or tissue destruction, but cannot adequately assess the normal range
High-sensitivity CRP (hs-CRP) assays (i.e. Dade Behring) detect levels of CRP within the normal range, levels proven to predict future cardiovascular events. Potential Mechanisms Linking CRP to Atherothrombosis Confounding by cigarette consumption
Innocent bystander - Acute phase response
Cytokine surrogate - IL-6, TNF-, IL-1
Direct effects of CRP - Innate immunity - Complement activation - CAM induction
Prior infection - Chlamydia, H pylori, CMV Marker for subclinical atherosclerosis - EBCT / IMT / ABI
Marker for insulin resistance/ obesity
Marker for endothelial dysfunction
Marker for dysmetabolic syndrome
Marker for plaque vulnerability hs-CRP and Risk of Future MI in Apparently Healthy Men 1 <0.055 Relative Risk of MI P = 0.03 Quartile of hs-CRP (range, mg/dL) 2 0.056–0.114 3 0.115–0.210 4 >0.211 P < 0.001 P < 0.001 P Trend <0.001 hs-CRP and Risk of Future Stroke in Apparently Healthy Men 1 <0.055 Relative Risk of Ischemic Stroke Quartile of hs-CRP (range, mg/dL) 2 0.056–0.114 3 0.115–0.210 4 >0.211 P =0.02 P =0.02 P Trend <0.03 hs-CRP and Risk of Developing PVD in Apparently Healthy Men None hs-CRP (mg/dL) Intermittent Claudication Peripheral Artery Surgery hs-CRP and Risk of Future Cardiovascular Events in Apparently Healthy Women 1 <0.15 Relative Risk Quartile of hs-CRP (range, mg/dL) 2 0.15–0.37 3 0.37–0.73 4 >0.73 P Trend <0.002 Any Event MI or Stroke hs-CRP and Risk of Future Cardiovascular Events in Apparently Healthy Women: Low-Risk Subgroups 1 <0.15 Relative Risk Quartile of hs-CRP (range, mg/dL) 2 0.15–0.37 3 0.37–0.73 4 >0.73 No hypertension
No current smoking
No family history hs-CRP and Coronary Heart Disease in Initially Healthy Men: MONICA–Augsburg Cohort 1 <0.6 Rate Ratio (Age Adjusted) Quartile of CRP (mg/dL) 2 0.6–1.1 3 1.1–2.2 4 2.2–4.5 5 >4.5 hs-CRP as a Risk Factor for Future CVD 1.0 2.0 3.0 4.0 5.0 6.0 Relative Risk (upper vs lower quartile) CHD Death
CHD 0 MRFIT (Kuller 1996)
PHS (Ridker 1997)
PHS (Ridker 1997)
CHS/RHPP (Tracy 1997)
PHS (Ridker 1998)
WHS (Ridker 1998, 2000)
MONICA (Koenig 1999)
Helsinki (Roivainen 2000)
Britain (Danesh 2000) hs-CRP Adds to the Predictive Value of Total Cholesterol in Determining Risk of First MI Adjusted Relative Risk CRP >75th percentile TC >75th percentile – + – + – + – + P = 0.02 P = 0.001 P = 0.002 hs-CRP Adds to Predictive Value of TC:HDL Ratio in Determining Risk of First MI Total Cholesterol:HDL Ratio hs-CRP Quartile of TC: HDL-C Quartile of hs-CRP hs-CRP, Lipids, and Risk of Future Coronary Events: Women's Health Study (WHS) Relative Risks for First MI for Baseline sICAM-1 >260 ng/dL Years of Study Follow-up 0–1 3
0 1–2 2–4 4–8 Relative Risk Predictivity of Interleukin-6 on CV Risk in Women 4
0 High Medium Low High Medium Low Interleukin-6 Total cholesterol