Coronary Artery calc proj
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Coronary Artery Calcification
& Computed Tomography Scoring
Coronary Artery Disease (CAD)
o CAD is the end result of the accumulation of atheromatous plaques in the walls of the coronary arteries. o CAD is the leading cause of death in the world. o CAD presents as a myocardial infarction (MI) or sudden cardiac death in ~50% of individuals with the pathology. o CAD is conventionally screened for by office-based risk screening methods, such as the Framingham Risk Score (FRS) in the US or the Prospective Cardiovascular Münster (PROCAM) study in Germany. o These screens only predict 60-65% of cardiovascular risk, not detecting many individuals who do not have traditional risk factors.
CAC Scoring
o In multiple studies the following definitions have been used to correlate the CAC score and the coronary plaque burden: o0 o 1 – 99 o 100 – 399 o >400 No identifiable disease Mild Disease Moderate Disease Severe Disease
CAC and Obstructive Disease
o CAC testing has a high sensitivity and high negative predictive value (NPV = 98%) for obstructive coronary artery disease (CAD), but limited specificity. o Therefore, CAC testing can be used to rule out angiographically significant CAD in symptomatic patients. o CAC could be used as a filter before catheterization – patients with a negative CAC would not continue to the cath lab. o This could save unnecessary catheterization procedures in patients presenting to the ED with chest pain. o In another scenario, a low CAC score precludes the need for a myocardial perfusion SPECT (MPS), since the probability of an abnormal scan would be extremely low. o Remember though, a positive CAC indicates atherosclerotic disease, and not necessarily obstruction from stenosis. o A person with an elevated CAC score may benefit from further functional testing to detect occult ischemia. o Functional testing is very important to determine the need for revascularization since functionally insignificant lesions do not benefit from revascularization.
Electron Beam and Multidetector CT
Problems imaging the heart: o Heart is beating (we hope!) o Beats are fast movements o Coronary arteries move a distance of several times their diameter each beat Electron Beam CT (EBCT) o Differs from conventional (helical/spiral) CT in that X-ray source is not rotated around patient o Obtains slices very quickly Multidetector CT (MDCT) o Much more widely available o Most coronary calcium studies use this o Multiple detectors allow increased imaging speed o Some detectors use EKG-gating to image diastole only (so coronary arteries are full)
Representative Images
o On CT, calcium has high attenuation values very bright!
Βιβλιοθήκη BaiduLCA
Framingham Models
o All adults should undergo an office-based assessment as an initial step to identify patients at higher-risk for a coronary event. o Risk Categories of the Framingham Models: o Defines risk of a cardiac event over 10 years. o Low: < 10% o Intermediate: 10-20% o High: > 20% o Framingham scores are population-based, and do not take into account an individual’s actual burden of atherosclerotic disease. o The majority of all cardiac events occurs in the intermediate risk cohort, yet treating all these individuals is cost-inefficient. o Therefore, CAC testing may detect those individuals in this risk group who actually have coronary atherosclerosis, and who would benefit from more aggressive therapy.
CT = Computed Tomography
The Test Procedure
o No special preparation, nor medication restrictions. o Patient lies in CT scanner for about 10 minutes and must hold breath between 10-30 seconds during imaging. o Radiation exposure: 0.7-3.0 mSv (milli-Sieverts) o Avg. yearly “natural” background exposure in US: 3 mSv o Diagnostic cardiac catheterization: 4.5 mSv o Coronary Artery Calcification (CAC) Score – Agatston Score o Based on area and density of calcified plaques o Typical report includes: o Agatston score for each major coronary artery o Total Agatston score for the patient o Several representative images
Coronary Atherosclerosis
o Atherosclerosis describes a chronic inflammatory process in arterial walls. o Associated with deposition of cholesterol by LDL without adequate removal by HDL. o Chronic atherosclerosis may lead to: o Stenosis and claudication o Plaque rupture and thrombosis o Long-standing association between arterial disease and calcification. o Calcification ≈ atherosclerosis o Furthermore, there is association between the presence of coronary calcification and risk of cardiovascular events.
CAC Predicts Cardiac Events
o CAC is a strong independent predictor of coronary events in both symptomatic and asymptomatic persons. o In a cohort of 10,377 asymptomatic persons followed for an average of 5 years, CAC was an independent predictor of death (p<0.001), with risk increasing proportionally with calcium scores. o A prospective study of 510 type II diabetics showed that CAC scoring predicted cardiovascular events better than the UK Prospective Diabetes Study Risk Score (0.74) and Framingham Score (0.60, p <0.0001) o When added to the Framingham Risk Score, CAC improves the predictive value of death estimation.
& Computed Tomography Scoring
Coronary Artery Disease (CAD)
o CAD is the end result of the accumulation of atheromatous plaques in the walls of the coronary arteries. o CAD is the leading cause of death in the world. o CAD presents as a myocardial infarction (MI) or sudden cardiac death in ~50% of individuals with the pathology. o CAD is conventionally screened for by office-based risk screening methods, such as the Framingham Risk Score (FRS) in the US or the Prospective Cardiovascular Münster (PROCAM) study in Germany. o These screens only predict 60-65% of cardiovascular risk, not detecting many individuals who do not have traditional risk factors.
CAC Scoring
o In multiple studies the following definitions have been used to correlate the CAC score and the coronary plaque burden: o0 o 1 – 99 o 100 – 399 o >400 No identifiable disease Mild Disease Moderate Disease Severe Disease
CAC and Obstructive Disease
o CAC testing has a high sensitivity and high negative predictive value (NPV = 98%) for obstructive coronary artery disease (CAD), but limited specificity. o Therefore, CAC testing can be used to rule out angiographically significant CAD in symptomatic patients. o CAC could be used as a filter before catheterization – patients with a negative CAC would not continue to the cath lab. o This could save unnecessary catheterization procedures in patients presenting to the ED with chest pain. o In another scenario, a low CAC score precludes the need for a myocardial perfusion SPECT (MPS), since the probability of an abnormal scan would be extremely low. o Remember though, a positive CAC indicates atherosclerotic disease, and not necessarily obstruction from stenosis. o A person with an elevated CAC score may benefit from further functional testing to detect occult ischemia. o Functional testing is very important to determine the need for revascularization since functionally insignificant lesions do not benefit from revascularization.
Electron Beam and Multidetector CT
Problems imaging the heart: o Heart is beating (we hope!) o Beats are fast movements o Coronary arteries move a distance of several times their diameter each beat Electron Beam CT (EBCT) o Differs from conventional (helical/spiral) CT in that X-ray source is not rotated around patient o Obtains slices very quickly Multidetector CT (MDCT) o Much more widely available o Most coronary calcium studies use this o Multiple detectors allow increased imaging speed o Some detectors use EKG-gating to image diastole only (so coronary arteries are full)
Representative Images
o On CT, calcium has high attenuation values very bright!
Βιβλιοθήκη BaiduLCA
Framingham Models
o All adults should undergo an office-based assessment as an initial step to identify patients at higher-risk for a coronary event. o Risk Categories of the Framingham Models: o Defines risk of a cardiac event over 10 years. o Low: < 10% o Intermediate: 10-20% o High: > 20% o Framingham scores are population-based, and do not take into account an individual’s actual burden of atherosclerotic disease. o The majority of all cardiac events occurs in the intermediate risk cohort, yet treating all these individuals is cost-inefficient. o Therefore, CAC testing may detect those individuals in this risk group who actually have coronary atherosclerosis, and who would benefit from more aggressive therapy.
CT = Computed Tomography
The Test Procedure
o No special preparation, nor medication restrictions. o Patient lies in CT scanner for about 10 minutes and must hold breath between 10-30 seconds during imaging. o Radiation exposure: 0.7-3.0 mSv (milli-Sieverts) o Avg. yearly “natural” background exposure in US: 3 mSv o Diagnostic cardiac catheterization: 4.5 mSv o Coronary Artery Calcification (CAC) Score – Agatston Score o Based on area and density of calcified plaques o Typical report includes: o Agatston score for each major coronary artery o Total Agatston score for the patient o Several representative images
Coronary Atherosclerosis
o Atherosclerosis describes a chronic inflammatory process in arterial walls. o Associated with deposition of cholesterol by LDL without adequate removal by HDL. o Chronic atherosclerosis may lead to: o Stenosis and claudication o Plaque rupture and thrombosis o Long-standing association between arterial disease and calcification. o Calcification ≈ atherosclerosis o Furthermore, there is association between the presence of coronary calcification and risk of cardiovascular events.
CAC Predicts Cardiac Events
o CAC is a strong independent predictor of coronary events in both symptomatic and asymptomatic persons. o In a cohort of 10,377 asymptomatic persons followed for an average of 5 years, CAC was an independent predictor of death (p<0.001), with risk increasing proportionally with calcium scores. o A prospective study of 510 type II diabetics showed that CAC scoring predicted cardiovascular events better than the UK Prospective Diabetes Study Risk Score (0.74) and Framingham Score (0.60, p <0.0001) o When added to the Framingham Risk Score, CAC improves the predictive value of death estimation.