Current Indications for Coronary Artery Calcium Scoring - Tri

Jas Kahlon M.D. F.A.C.C
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Faculty Disclosure
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First whole-body CT cross-section through a human thorax,
generated by Ledley et al in 1974 (Science 1974;186:207)
The Examination
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EBCT or MDCT ( higher spatial resolution)
Agatston, area x density ( 1-4)
CVS, calcium volume score , progression
monitoring
Shell like and diffuse calcifications correlate
with severe stenosis v/s nodular calcifications
Cut-point 371 at least one coronary with
more than 70% ( high sens. and spec.)
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PA/Lateral CXR
0.04-0.06 mSv
Head CT
1-2 mSv
Chest CT
5-7 mSv
CAC
1.5mSv
Abd/Pelvis CT
8-11 mSv
Diagnostic Cor Angiogram 3-5 mSv
MSCT angiography
9.3-11.3 mSv
*Average annual background radiation in U.S ~ 3.6 mSv
Morin et al. Circulation 2003;107:917-22.
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2010 ACC/AHA guidelines
◦ II a Intermediate risk population ( 10-20% 10
year risk)
◦ II b low to intermediate risk ( 6-10% 10 year
risk)
◦ III for low risk population , less than 6% annual
risk
◦ Exception for patients with family history of
premature coronary artery disease
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Why CAC ?
• Independent incremental value in prediction of all
cause mortality in asymptomatic cohort group
• Superior value over FRS
stenosis burden
in predicting the proximal
• Reclassification of CAD risk
categories: 60% of
coronary atherosclerotic events occur in patients in low or
intermediate-Framingham risk categories (12). Intermediaterisk patients with CACS >300 had a 2.8% annual rate of cardiac
death or MI (roughly equivalent to a 10-year rate of 28%) that
would put them in a high risk category
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From: Coronary Artery Calcification: Pathogenesis and Prognostic Implications
J Am Coll Cardiol. 2014;63(17):1703-1714. doi:10.1016/j.jacc.2014.01.017
Figure Legend:
Select Studies Demonstrating Improved Risk Stratification of CHD Events With Use of CAC Scores
(A) With data from the MESA (Multi-Ethnic Study of Atherosclerosis) (35), a demonstration that the addition of the coronary artery
calcification (CAC) score to Framingham risk factors (age, sex, smoking, systolic blood pressure, use of antihypertensive
medications, and lipid status) led to an improvement in prediction of coronary heart disease (CHD) events. Specifically, there was a
significant shift in the number of patients reclassified from intermediate (3% to 10% risk of CHD events in 5 years) to high risk (>10%
Date
Copyright
© The
of Rotterdam
Cardiology.study (33). With the addition of CAC scores to
riskofofdownload:
CHD events in 5 years). (B) Similar
findings
areAmerican
presentedCollege
from the
9/1/2014
Allmen
rights
reserved.
a refitted Framingham model, 52% of
and
women from the intermediate-risk group were reclassified to a different risk category.
CAC and Event rates
• Pooled data from 6 studies of 27,622 asymptomatic patients
examined predictors of CAD deaths or MIs (10).
• The 11,815 subjects who had CAC Score of 0 had a low rate of
events over the subsequent 3 to 5 years (0.4%).
• Compared with a CAC Score of 0, a CAC Score (100-400)
indicated a relative risk (RR) of 4.3 (95% CI, 3.5-5.2; P<0.0001)
• a score of (400-1,000) indicated a RR of 7.2 (95% CI, 5.2-9.9;
P<0.0001)
• score >1,000 indicated a RR of 10.8 (95% CI, 4.2-27.7;
P<0.0001).
• Incremental relationship where higher CAC scores are
associated with higher event rates and higher relative risk
ratios. Brown et al.
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Brown BG, Morse J, Zhao XQ, et al. Electron-beam tomography coronary
calcium scores are superior to Framingham risk variables for predicting the
measured proximal stenosis burden. Am J Cardiol 2001;88:23E-6E.
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The calcium scale is a linear scale with 4 calcium
score categories:
0
1–99
100–400
>400
none
mild
moderate
severe
*Calcium score correlates directly with risk of
events and likelihood of obstructive CAD*
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Figure 2 Rates of Incident CHD/1,000 Person Years at Risk by Joint Categories of Absolute CAC Group and Age-SexRace/Ethnicity–Specific Percentiles Displays the rates of incident CHD/1,000 person years at risk by joint categories of absolute CAC
group and...
Matthew J. Budoff , Khurram Nasir , Robyn L. McClelland , Robert Detrano , Nathan Wong , Roger S. Blumenthal , Geo...
Coronary Calcium Predicts Events Better With Absolute Calcium Scores Than Age-Sex-Race/Ethnicity Percentiles : MESA
(Multi-Ethnic Study of Atherosclerosis)
Journal of the American College of Cardiology, Volume 53, Issue 4, 2009, 345 - 352
http://dx.doi.org/10.1016/j.jacc.2008.07.072
Figure 1 Pathophysiology of CAC Progression Increasing coronary artery calcification (CAC) increases risk for future events. CAC
progression occurs in 3 subgroups: 1) incident CAC; 2) calcified nonprogressors; and 3) CAC progressors.
John W. McEvoy , Michael J. Blaha , Andrew P. DeFilippis , Matthew J. Budoff , Khurram Nasir , Roger S. Blumenthal...
Coronary Artery Calcium Progression: An Important Clinical Measurement? : A Review of Published Reports
Journal of the American College of Cardiology, Volume 56, Issue 20, 2010, 1613 - 1622
Is Calcified Plaque better?
• Increased local coronary calcification might be
associated with increased cardiac risk by its
association with increased total plaque burden,
including both noncalcified and mixed plaque subtypes
(Fig. 1)
• Because less mature plaques calcify after they rupture
and heal, new highly calcified lesions might
represent a propensity for active
atherosclerosis deposition and rupture throughout
the coronary tree
• Research also suggests that mixed plaques, which
contain early calcification near the plaque
shoulders, increase the propensity for plaque fracture
(52).
Does coronary CT angiography improve risk stratification over coronary
calcium scoring in symptomatic patients with suspected coronary artery
disease? Results from the prospective multicenter international
CONFIRM registry
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symptomatic patients with suspected but without known CAD Chest pain
or dyspnea
pre-test likelihood of obstructive CAD was assessed by the method of
Diamond and Forrester (D–F)
CCTAs were graded for obstructive CAD (>70% stenosis); CAD plaque
burden, distribution, and location.
segment stenosis score (SSS), which reflects the number of coronary
segments with plaque, weighted for stenosis severity.
segment-involvement score (SIS), which reflects the number of segments
with plaque irrespective of stenosis severity.
Finally, a modified Duke index— stenosis severity, plaque distribution,
and plaque location—was calculated.
composite endpoint of all-cause mortality and non-fatal myocardial
infarction (D/MI) to assess the incremental prognostic value of CCTA over
CAC
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. A total of 8627 symptomatic patients (50% men, age 56 ± 12
years) followed for 25 months (interquartile range 17–40 months)
By CAC, 4860 (56%) and 713 (8.3%) patients had no evident calcium
or a score of >400, respectively.
By CCTA, 4294 (49.8%) and 749 (8.7%) had normal coronary
arteries or obstructive CAD, respectively.
At follow-up, 150 patients experienced D/MI.
CAC improved discrimination beyond D–F and clinical variables
( P = 0.004).
When added sequentially to D–F, clinical variables, and CAC, all
CCTA measures of CAD improved discrimination of patients at risk
for D/MI: obstructive CAD (0.82, P < 0.001), SSS (0.81, P < 0.001),
SIS (0.81, P = 0.003), and Duke CAD prognostic index (0.82, P <
0.0001).
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CONFIRM REGISTRY
CAC 0
• In patients with a CAC score of 0, 16% of patients had evidence of some
degree of CAD on CCTA, with 13% of patients with a CAC score of 0 having
nonobstructive CAD (<50% stenosis). The prevalence of any major
epicardial vessel with ≥50% and ≥70% stenosis on CCTA among patients
with a CAC score of 0 was 3.5% and 1.4%, respectively. The majority of
patients with a CAC score of 0 and obstructive CAD (n = 180) had singlevessel disease (82%), with a lower prevalence of 2-vessel (12%), 3-vessel
(6%), and left main (0.3%) disease.
• However, recent studies have shown significantly higher rates of
obstructive CAD in patients with a CAC score of 0, ranging from 7% to 38%
of patients (8-13), especially with higher risk presentations, consistent
with Bayesian reasoning. The prevalence of significant CAD in patients with
a CAC score of 0 primarily at intermediate pre-test risk in CONFIRM study
was lower, reaffirming the importance of pre-test probability
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From: Prevalence and Severity of Coronary Artery Disease and Adverse Events Among Symptomatic Patients
With Coronary Artery Calcification Scores of Zero Undergoing Coronary Computed Tomography
Angiography: Results From the CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes:
An International Multicenter) Registry
Figure Legend:
Coronary Artery Stenosis on CCTA
Increasing frequency of obstructive disease with increasing coronary artery calcification (CAC) (Agatston) scores is demonstrated.
*p < 0.001 between groups. CCTA = coronary computed tomography angiography.
J Am Coll Cardiol. 2011;58(24):2533-2540. doi:10.1016/j.jacc.2011.10.851
Date of download:
9/5/2014
Copyright © The American College of Cardiology.
All rights reserved.
Relation between CAC and composite endpoint of death or non-fatal MI, demonstrating a
graded risk with increasing CAC (P < 0.0001).
Al-Mallah M H et al. Eur Heart J Cardiovasc Imaging
2013;ehjci.jet148 CONFIRM REGISTRY
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author
2013. For permissions please email: [email protected]
Flow chart showing prognosis of entire study cohort during follow-up.
Kim Y J et al. Eur Heart J Cardiovasc Imaging
2012;ehjci.jes060
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author
2012. For permissions please email: [email protected]
• The main findings revealed that in symptomatic patients with a
CCS of zero, the prevalence of obstructive CAD by CCTA was
not negligible (4.3%; 7% of the men and 2% of the women)
• zero CCS could not guarantee their mid-term prognosis:
elective revascularization was done in 2.2% of the patients
(3.8% of the men and 1.1% of the women)
• composite MACEs occurred in 1.3% (1.7% of the men and 0.9%
of the women).
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1/3rd all deaths world wide due to ASCVD
1/2 occur in previously asymptomatic
patients
70% of the Acute coronary events occur in
non flow limiting lesions
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Calcium score zero doesn’t mean no CAD,
especially in a symptomatic patient
High calcium score doesn’t mean severe focal
stenosis, Does mean high risk of future
events
Main function is risk stratification in
asymptomatic populations
Diabetics and family history of premature
coronary disease
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Calcium Volume Scoring
Area = 8 mm2
Peak CT = 290
Score = 8 x 2 = 16
Area = 15 mm2
Peak CT = 450
Score = 15 x 4 = 60
Total Score = S
Hn x-factor
(Agatston Scoring)
130-199
1
200-299
2
300-399
3
>400
4
6814 men and women aged 45-84 years
Bild DE et al. Circulation. 2005;111:1313-1320.
*
*p<0.001
*
*
Shaw et al. Radiology 2003; 228:826-833
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MI in 41 pts during
3.2 + 0.7 years
LDL levels similar in
MI and non-MI pts
Relative risk of MI
in presence of CAC
progression was
17.2-fold higher
(P<0.0001)
Raggi P et al. Arterioscler Thromb Vasc Biol. 2004;24:1272-77.
Coronary Disease Progression
Calcified Plaque Detected by CT
? Role for CTA
>60% stenosis (+)
stress/imaging
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Exact quantification of harmful effects of
radiation difficult to ascertain
For a child under age 15, the risk of cancer
death from a single CT scan is
approximately 1 in 500
For a 45 year old adult, the risk of death
from cancer from a single CT exam is about
1 in 1,250
Brenner et al. Radiology, 231(2):440-445.
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Calcium Scoring (CS) - risk stratification in
the intermediate risk patient
Non-invasive coronary angiography (CTA)
in the symptomatic low-risk patient or
asymptomatic intermediate-risk patient
*A negative test (normal CTA) has a 98%
chance of revealing normal coronary
arteries on invasive angiography*
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Association for the Eradication of Heart Attacks (AEHA.org)
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70 patients undergoing invasive cath
Of 1,065 segments, 935 evaluated (88%)
Quantitative assessment in 773 of 935
segments by MSCT and QCA
Sensitivity, specificity, (+) PV, (-) PV:
◦ By segment◦ By artery◦ By patient-
(86%, 95%, 66%, and 98%)
(91%, 92%, 80%, and 97%)
(95%, 90%, 93%, and 93%)
Raff GL et al. J Am Coll Cardiol. Aug 2, 2005;46:552-7.