Comparison of Carotid Plaque Score and Coronary Artery

Comparison of Carotid Plaque Score and Coronary Artery Calcium Score for Predicting CVD Events in MESA Adam Gepner, MD University of Wisconsin School of Medicine and Public Health

DISCLOSURES: NONE

Abstract

Background u CAC predicts coronary heart disease (CHD) events better than carotid wall thickness and carotid plaque presence u CAC scoring may not detect non-calcified plaques u CAC may underestimate stroke/transient ischemic attack (TIA) risk compared with carotid plaque u Comparative efficacy of CAC score & carotid plaque score for CVD risk prediction is unclear

Objective To compare and describe the abilities of CAC score and carotid plaque score to predict CVD events in a large, multiethnic cohort with long-term follow-up

Participants and Design u The Multi-Ethnic Study of Atherosclerosis (MESA) is a longitudinal prospective, cohort study u Participants were 45 -84 years old and free of known CVD at baseline (20002002) u CVD events (CVD death, CHD, and stroke) and TIAs adjudicated

CAC and Plaque Methods u CAC detected by computed tomography and Agatston scores determined u Carotid plaque detected by B-mode US • Focal abnormal wall thickness (IMT >1. 5 mm) • Focal thickening >50% of the IMT u Carotid plaque score calculation • # of plaques in the common, bifurcation, and internal carotid arteries • Range 0 -12

Plaque Score Examples: Right internal carotid artery Left carotid bifurcation Left external carotid artery Left common carotid artery Right carotid bifurcation Right external carotid artery Right common carotid artery

Statistical Analysis u CAC score analyzed as ln(CAC+1) u Carotid plaque score analyzed as: • ln(score +1) • Untransformed u SD units u Predictive values compared • Cox proportional hazards models, C-statistics, NRIs u Models factors adjusted for traditional CVD risk

Baseline Demographics Complete Cases* All Participants** 4, 955 6, 783 Age (years) 61. 6 (10. 1) 62. 2 (10. 2) Male sex, % (n) 47. 2 (2, 339) 47. 16 (3, 199) 38. 8 (1, 924) 38. 5 (2, 614) 12. 4 (614) 11. 8 (801) Black 26. 0 (1, 288) 27. 7 (1, 880) Hispanic 22. 8 (1, 129) 21. 9 (1, 488) 28. 3 (5. 5) Mean (SD) unless noted Analytic sample size (n) Race/ethnicity, % (n) White Chinese Body-mass index (kg/m 2)

Baseline Demographics Complete Cases All Participants Former smoker, % (n) 36. 6 (1, 812) 36. 7 (2, 486) Current smoker, % (n) 12. 86 (636) 13. 1 (885) LDL cholesterol (mg/d. L) 117. 3 (31. 5) 117. 8 (31. 5) HDL cholesterol (mg/d. L) 50. 8 (14. 8) 51. 0 (14. 8) Lipid-lowering medication, % (n) 16. 1 (796) 16. 3 (1, 102) Systolic blood pressure (mm. Hg) 126. 2 (21. 6) 126. 6 (21. 5) Diastolic blood pressure (mm. Hg) 71. 9 (10. 3) Antihypertensive medication, % (n) 36. 4(1, 803) 37. 3 (2, 528) Untreated diabetes mellitus, % (n) 2. 5 (125) 2. 6 (179) Treated diabetes mellitus, % (n) 9. 5 (468) 9. 9 (672) Mean (SD) unless noted

Events Complete Cases* All Participants** 4, 955 6, 783 9. 8 (487) 10. 5 (709) 2. 1 (102) 2. 1 (143) 7. 0 (348) 7. 3 (498) 1. 3 (63) 1. 2 (84) Stroke, % (n) 2. 7 (136) 2. 7 (200) Stroke + TIA, % (n) 3. 5 (175) 3. 9 (262) Analytic sample size (n) CVD event, % (n) CVD death, % (n) CHD event, % (n) CHD death, % (n)

Results u 2, 424 (48. 9%) had CAC • Mean score of 270. 6 (519. 9) u 2, 516 (50. 8%) had carotid plaque • Mean score of 2. 6 (1. 8) u 11. 3 (3. 0) years follow-up u CAC and carotid plaque scores improved risk prediction compared with traditional CVD RFs u CAC score was a stronger predictor than carotid plaque score for both CVD and CHD

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Adjusted Models

Discussion u CAC score and carotid plaque score improved prediction of CVD and CHD events compared to traditional CVD risk factors u Adjusted HRs, C-statistics, and NRI values consistently were higher for CAC score than for carotid plaque score u For stroke and TIA events, CAC and carotid plaque score performed similarly

Limitations u Subset of the entire MESA cohort • Possible survivorship bias • Small number of stroke and TIA events u Units of CAC score and carotid plaque score are not equal or equally spaced • CAC score ranges from 0 to infinity; carotid plaque score from 0 -12 • Regression coefficients presented in SD units of the measure to permit a more direct comparison

Conclusions u CAC score improves prediction, discrimination, and reclassification of CVD and CHD risk better than carotid plaque score u CAC and carotid plaque scores had similar prediction and weaker discrimination and reclassification for stroke/TIA events

Funding Sources Contracts N 01 -HC-95159 through N 01 HC-95169 from the NHLBI, grant ES 015915 from the NIEHS, grant R 831697 from the US EPA, grants UL 1 -RR 024156 and UL 1 -RR-025005 from the NCRR, and by a T 32 HL-07936 Ruth L. Kirschstein National Research Service Award from the NHLBI to the University of Wisconsin-Madison Cardiovascular Research Center

Acknowledgements u James Stein u Rebekah Young u AIRP Lab • Claudia Korcarz • Kristin Hansen • Jo. Anne Weber • Jessica Horn u Co-Authors u MESA Steering Committee

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