Coronary heart disease risk stratification

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Risk calculators and risk factors for Coronary heart disease risk stratification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Risk stratification among patients with and at risk for coronary artery disease is critical so that the level of aggressiveness of management can match the risk of future events. The magnitude of risk is often clearer in the patient who has had a vascular event than in the assessment of primary risk assessment (who will have a future event who does not yet have evidence of CHD). Patients at low to intermediate risk by history and physical examination account for 75% of cardiovascular events. There is therefore the need for improved risk stratification tools to reclassify those patients deemed to be at low risk on history and physical examination into a higher risk category. In select populations, coronary artery Ca scoring, carotid intima-media thickness (CIMT) assessment and C reactive protein (CRP) assessment may offer addition improvements in risk stratification.

Risk Equivalents in Primary Prevention

You are essentially considered to have the equivalent of coronary heart disease if you have any of the following:

• Aortic aneurysm
• Diabetes
• Framingham Risk Score (FRS) of > 20%
• Peripheral vascular disease (PVD) (defined as claudication, an Ankle Brachial Index (ABI) of < 0.9)
• Symptomatic carotid artery disease (defined as prior stroke or TIA)

CV Risk Factors in the Setting of Primary Prevention

• Cigarette smoking
• Family history of premature coronary artery disease (CAD)
• High LDL (defined as LDL > 130 mg /dl)
• Hypertension ( defined as a BP ≥140/90 mm Hg or if the patient is on antihypertensive drugs)
• Low HDL (defined as HDL < 40 mg/dL males, < 50 mg/dL in females)
• Older Age (men ≥45 years old; women ≥55 years old)

Risk Stratification

Framingham risk calculator

The Framingham Risk Score is used to estimate the 10-year cardiovascular risk of an individual. The Framingham Risk Score is based on data obtained from the Framingham Heart Study. There are two Framingham Risk Scores, one for men and one for women.

- Low Risk is less than 10%

- Intermediate Risk is 10 - 20%

- High Risk is more than 20%

Stress EKG: Duke Treadmill Score

Duke treadmill score(DTS) = Treadmill time (Bruce) - 5 x ST deviation (no. mm) - 4 x Angina index (0,1,2)

Low Risk Score	>= 5	Treat medically
Intermediate Score	-10 to 4	Stress Imaging
High Risk Score	<= -11	Cath/PCI/CABG

Stress Imaging

Stress imaging is induction of reversible ischemia in a patient using drugs which can can cause increased contraction of heart muscle like dobutamine or drugs which cause vasodilatation and decrease blood supply to heart. Both these mechanisms cause stress on heart.

ACC/AHA guidelines for Stress Imaging

Class I

" 1. Symptomatic, able to exercise , uninterpretable ECG."

" 2. Symptomatic, unable to exercise."

" 3. Symptomatic prior coronary revascularization."

" 4. Functionally significant lesion."

" 5. Intermediate risk on Duke Treadmill Score."

Stress Imaging Results

Low risk findings

• It has normal or near normal MPI
• Normal stress echo
• The annual mortality rate in these patients will be < 1%

Intermediate risk findings

• Mild to moderate dysfunction of left ventricle. (resting ejection fraction of 35- 49%)
• Moderate stress induced perfusion defect without LV dilatation or increased uptake into pulmonary vessels.
• mild to moderate stress induced regional wall motion abnormalities in echocardiogram seen in upto 4 segments.
• The annual mortality rate of these patients will be 1 - 3%.

High risk findings

• Significant LV dysfuntion. (resting ejection fraction of <40%%)
• Abnormal left ventricular end systolic volume.
• Extensive ischemic regional wall motion abnormality in more than 5 segments.
• Low ischemic threshold during stress echo.
• Multi-vessel regional wall motion abnormality.
• The annual mortality rate in these patients will be > 3%.

LV function assessment

Class I

Echo/RNA(radionuclide ventriculography) if history of MI, path. Q waves, signs or symptoms of CHF or VHD, or ventricular arrhythmias.

Class III (No Benefit)

Echo/RNA if normal ECG, no History of MI, no symptoms and signs of CHF, VHD, or HCM. Echo/RNA if no clinical change.

2010 ACCF/AHA Guideline for Assessment of Cardiovascular Risk in Asymptomatic Adults (DO NOT EDIT)

Global Risk Scoring (DO NOT EDIT)

Class I

"1. Global risk scores (such as the Framingham Risk Score) that use multiple traditional cardiovascular risk factors should be obtained for risk assessment in all asymptomatic adults without a clinical history of CHD. These scores are useful for combining individual risk factor measurements into a single quantitative estimate of risk that can be used to targe preventive interventions. (Level of Evidence: B)"

Family History (DO NOT EDIT)

Class I

"1. Family history of atherothrombotic CVD should be obtained for cardiovascular risk assessment in all asymptomatic adults. (Level of Evidence: B)"

Class III Contraindications for Risk Stratification Tests in the Asymptomatic Patient in Primary Prevention

Class III (No Benefit)

"There is no role for the following tests in the asymptomatic patient:"

"1. Genetic testing (Level of Evidence: B) "

"2. Measurement of lipid parameters, including lipoproteins, apolipoproteins, particle size, and density, beyond standard fasting lipid profile is not recommended for cardiovascular risk assessment in asymptomatic adults. (Level of Evidence: C) "

"3. Measurement of natriuretic peptides is not recommended for CHD risk assessment in asymptomatic adults. (Level of Evidence: B) "

"4. Echocardiography is not recommended for cardiovascular risk assessment of CHD in asymptomatic adults without hypertension. (Level of Evidence: C) "

"5. Peripheral arterial flow-mediated dilation studies are not recommended for cardiovascular risk assessment in asymptomatic adults. (Level of Evidence: B) "

"6. Measures of arterial stiffness outside of research settings are not recommended for cardiovascular risk assessment in asymptomatic adults. (Level of Evidence: C) "

"7. Stress echocardiography is not indicated for cardiovascular risk assessment in low- or intermediate-risk asymptomatic adults. (Exercise or pharmacological stress echocardiography is primarily used for its role in advanced cardiac evaluation of symptoms suspected of representing CHD and/or estimation of prognosis in patients with known CAD or the assessment of patients with known or suspected valvular heart disease.) (Level of Evidence: C) "

"8. Coronary artery calcium scoring in low risk patients. Persons at low risk (<6% 10-year risk, i.e. a Framingham Risk Score of <6%) should not undergo CAC measurement for cardiovascular risk assessment. (Level of Evidence: B) "

"9. CRP testing should be confined to intermediate risk patients similar to the Jupiter trial population and should not be done in low and high risk patients. In asymptomatic high-risk adults, measurement of CRP is not recommended for cardiovascular risk assessment. (Level of Evidence: B) In low-risk men younger than 50 years of age or women 60 years of age or younger, measurement of CRP is not recommended for cardiovascular risk assessment. (Level of Evidence: B) "

"10. Coronary Computed Tomography Angiography is not recommended for cardiovascular risk assessment in asymptomatic adults. (Level of Evidence: C) "

"11. Magnetic Resonance Imaging of Plaque for detection of vascular plaque is not recommended for cardiovascular risk assessment in asymptomatic adults. (Level of Evidence: C) "

"12. Stress Myocardial Perfusion Imaging is not indicated for cardiovascular risk assessment in low- or intermediate-risk asymptomatic adults. (Exercise or pharmacologic stress MPI is a technology primarily used and studied for its role in advanced cardiac evaluation of symptoms suspected of representing CHD and/or estimation of prognosis (i.e. the size of the ischemic defect in patients with known coronary artery disease.) (Level of Evidence: C) "

Class II Indications for Risk Stratification Tests in Primary Prevention

The utility of the following three tests varies depending upon the pre-test probability of risk in the patient. Like all tests, these risk stratification tests provide the greatest information to guide decision making in the intermediate risk patient. Among patients who are low risk or high risk, these tests likely do not change management decisions. Three of these tests (coronary artery Ca sclring, CIMT and CRP assessment) reclassify risk beyond traditional risk factors in about 25% of patients.

Calcium Scoring Methods (DO NOT EDIT)

Class IIa

"1. Measurement of CAC is reasonable for cardiovascular risk assessment in asymptomatic adults at intermediate risk (10% to 20% 10-year risk). (Level of Evidence: B)"

Class IIb

"1. Measurement of CAC may be reasonable for cardiovascular risk assessment persons at low to intermediate risk (6% to 10% 10-year risk). (Level of Evidence: B)"

Measurement of Carotid Intima-Media Thickness (DO NOT EDIT)

Class IIa

"1. Measurement of carotid artery intima-media thickness is reasonable for cardiovascular risk assessment in asymptomatic adults at intermediate risk. Published recommendations on required equipment, technical approach, and operator training and experience for performance of the test must be carefully followed to achieve high-quality results. (Level of Evidence: B)"

Measurement of C-Reactive Protein (DO NOT EDIT)

Class III: No Benefit

"1. In asymptomatic high-risk adults, measurement of CRP is not recommended for cardiovascular risk assessment. (Level of Evidence: B)"

"2. In low-risk men younger than 50 years of age or women 60 years of age or younger, measurement of CRP is not recommended for cardiovascular risk assessment. (Level of Evidence: B)"

Class IIa

"1. In men 50 years of age or older or women 60 years of age or older with low-density lipoprotein cholesterol less than 130 mg/dL; not on lipid-lowering, hormone replacement, or immunosuppressant therapy; without clinical CHD, diabetes, chronic kidney disease, severe inflammatory conditions or contraindications to statins, measurement of CRP can be useful in the selection of patients for statin therapy. (Level of Evidence: B)"

Class IIb

"1. In asymptomatic intermediate-risk men 50 years of age or younger or women 60 years of age or younger, measurement of CRP may be reasonable for cardiovascular risk assessment. (Level of Evidence: B)"

Measurement of Hemoglobin A1C (DO NOT EDIT)

Class IIb

"1. Measurement of hemoglobin A1C may be reasonable for cardiovascular risk assessment in asymptomatic adults without a diagnosis of diabetes. (Level of Evidence: B)"

Lipoprotein-Associated Phospholipase A2 (DO NOT EDIT)

Class IIb

"1. Lipoprotein-associated phospholipase A2 might be reasonable for cardiovascular risk assessment in intermediate-risk asymptomatic adults. (Level of Evidence: B)"

Testing for Microalbuminuria (DO NOT EDIT)

Class IIa

"1. In asymptomatic adults with hypertension or diabetes, urinalysis to detect microalbuminuria is reasonable for cardiovascular risk assessment. (Level of Evidence: B)"

Class IIb

"1. In asymptomatic adults at intermediate risk without hypertension or diabetes, urinalysis to detect microalbuminuria might be reasonable for cardiovascular risk assessment. (Level of Evidence: B)"

Resting Electrocardiogram (DO NOT EDIT)

Class IIa

"1. A resting electrocardiogram (ECG) is reasonable for cardiovascular risk assessment in asymptomatic adults with hypertension or diabetes. (Level of Evidence: C)"

Class IIb

"1. A resting ECG may be considered for cardiovascular risk assessment in asymptomatic adults without hypertension or diabetes. (Level of Evidence: C)"

Transthoracic Echocardiography (DO NOT EDIT)

Class IIb

"1. Echocardiography to detect left ventricular hypertrophy may be considered for cardiovascular risk assessment in asymptomatic adults with hypertension. (Level of Evidence: B)"

Class III: No Benefit

"1. Echocardiography is not recommended for cardiovascular risk assessment of CHD in asymptomatic adults without hypertension. (Level of Evidence: C) "

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Brachial/Peripheral Flow-Mediated Dilation (DO NOT EDIT) ===

Class III: No Benefit

"1. Peripheral arterial flow-mediated dilation (FMD) studies are not recommended for cardiovascular risk assessment in asymptomatic adults. (Level of Evidence: B)"

Ankle-Brachial Index Recommendation

Class IIa

"1. Measurement of ankle-brachial index is reasonable for cardiovascular risk assessment in asymptomatic adults at intermediate risk. (Level of Evidence: B) "

Exercise Electrocardiography Recommendation

Class IIb

"1. An exercise ECG may be considered for cardiovascular risk assessment in intermediate-risk asymptomatic adults (including sedentary adults considering starting a vigorous exercise program), particularly when attention is paid to non-ECG markers such as exercise capacity. (Level of Evidence: B) "

Myocardial Perfusion Imaging Recommendations

Class IIb

"1. Stress myocardial perfusion imaging (MPI) may be considered for advanced cardiovascular risk assessment in asymptomatic adults with diabetes or asymptomatic adults with a strong family history of CHD or when previous risk assessment testing suggests a high risk of CHD, such as a coronary artery calcium (CAC) score of 400 or greater. (Level of Evidence: C) "

Additional Considerations

• Patients With Diabetes Recommendations

Class IIa

"1. In asymptomatic adults with diabetes, 40 years of age and older, measurement of CAC is reasonable for cardiovascular risk assessment. (Level of Evidence: B) "

Class IIb

"1. Measurement of hemoglobin A1C may be considered for cardiovascular risk assessment in asymptomatic adults with diabetes. (Level of Evidence: B) "

"1. Stress MPI may be considered for advanced cardiovascular risk assessment in asymptomatic adults with diabetes or when previous risk assessment testing suggests a high risk of CHD, such as a CAC score of 400 or greater. (Level of Evidence: C) "

• Women Recommendations

Class I

"1. A global risk score should be obtained in all asymptomatic women. (Level of Evidence: B) "

"2. Family history of CVD should be obtained for cardiovascular risk assessment in all asymptomatic women. (Level of Evidence: B) "