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251 computed tomographic coronary artery calcium

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251 computed tomographic coronary artery calcium

  1. 1. CRP + Calcium Score; More Powerful Together Provided by: M. Leila Rasouli, M.D. Division of Cardiology, Harbor UCLA Medical Center Editorial Slides VP Watch – October 30, 2002 - Volume 2, Issue 43
  2. 2. Computed Tomographic Coronary Artery Calcium (CAC) • A manifestation of subclinical atherosclerosis • A Recent meta-analysis reported a pooled 4-fold relative risk (RR) for CAC as a predictor of myocardial infarction (MI) or coronary death.1
  3. 3. High-sensitivity C-Reactive Protein (CRP) • A measure of chronic inflammation • Serum levels of CRP in highest tertile predict future coronary events in asymptomatic men2 and postmenopausal women.3,4 • Elevated CRP levels impart an approximately 2-fold risk of coronary events after adjustment for demographic and risk factors.
  4. 4. South Bay Heart Watch (SBHW) • As reported in VP Watch of this week, a prospective cohort study designed to appraise the value of coronary calcium and both traditional & non-tradidtional risk factors for cardiovascular outcomes in asymptomatic adults • Objective of investigation: To evaluate prospectively the combined use of CT coronary calcium scores & high-sensitivity CRP in predicting cardiovascular events in SBHW cohort of nondiabetics
  5. 5. Methods • SBHW cohort: n=1461. Asymptomatic participants ≥ 45 yo with multiple cardiac risk factors • Study inclusion criteria: SBHW cohort who were nondiabetic5 and CRP ≤10 mg/L • Exclusion criteria: Participants with ECG/clinical evidence of infarction, revascularization, or typical angina
  6. 6. Methods • Enrollment: between December 1990 –December 1992 • Final N= 967 • Baseline and follow-up risk factor screening, CT for CAC, and CRP measurement conducted • Follow-up: 6.4 ± 1.3 years
  7. 7. Methods • Study end points: 1)nonfatal MI or coronary death, 2 )any cardiovascular event (MI, coronary death, coronary revascularization, or stroke) • Statistical Analysis: t-test, Cox regression analyses, all analyses conducted at .05 significance level and used SAS software
  8. 8. Results • 50 participants experienced MI/coronary death endpoint • Participants with MI/coronary death had higher systolic BP and lower HDL cholesterol • 104 participants experienced any cardiovascular event (CV) • Participants with any CV event were older, less likely to smoke, took ASA, had higher BP and BMI, and lower HDL
  9. 9. Results • Median calcium score was 5 times greater in participants who had an event than in those who did not (p<0.0001) • Significantly larger CRP values for those who experienced end points (p=0.002)
  10. 10. Results • Calcium score was a statistically significant predictor of both end points (p<0.005) • CRP was a marginally significant predictor of MI/coronary death (p=0.09) & statistically significant predictor of any CV event (p=0.03)
  11. 11. Results • Risk group analysis defined by tertiles for CAC (<3.7, 3.7-142.1, >142.1) and the 75th percentile for CRP (>4.05 mg/L) indicated increasing risk with increasing CAC and CRP
  12. 12. Results • RR for medium-calcium/low CRP risk group to high-calcium/high CRP risk group ranged from 1.8-6.1 for MI/coronary death (p=0.003) • For any CV event: RR ranged from 2.8-7.5 (p<0.001)
  13. 13. 6.1 4.3 1.7 4.9 1.8 1 0 2 4 6 8 High Medium Low Low High Relative risks of nonfatal MI or coronary death associated with high (> 75th percentile = 4.05 mg/L) and low (<4.05 mg/L) levels of CRP and high (> 142.1), medium (3.7 to 142.1) and low (< 3.7) tertiles of calcium scores.
  14. 14. 7.5 3.4 1.64.4 2.8 1 0 2 4 6 8 High Medium Low Low High Relative risks of nonfatal MI, coronary death, PTCA, CABG, or stroke associated with high (> 75th percentile = 4.05 mg/L) and low (<4.05 mg/L) levels of CRP and high (> 142.1, medium (3.7 to 142.1) and low (< 3.7) tertiles of calcium scores.
  15. 15. Discussion • Risk-adjusted analysis revealed CAC and CRP are associated with ischemic cardiovascular events in previously asymptomatic nondiabetic adults • Lack of interaction in nondiabetics between CRP levels and CAC along with the complementary predictive power of the 2 tests suggests that they assess different aspects/mechanisms that result in CV events
  16. 16. Limitations • Participants homogeneous (older men) • Statistical analyses could not control for all possible relevant confounders (ie physical activity) • CRP levels in the study were greater than those derived from a meta-analysis based on 14 population-based studies.4
  17. 17. Conclusion • Combined use of calcium scores and CRP improves risk stratification in non-diabetic patients. • Use of combined testing with CT and CRP appears to complementary.
  18. 18. Question • What is the exact role of both calcification and CRP in the development of atherosclerosis and cardiovascular events? – Only markers of disease? – CRP is a marker but calcification is a risk factor? – Calcification is a marker but CRP is a risk factor? – Both are risk factors?
  19. 19. References 1) O’Malley PG, Taylor AJ, Jackson JL, et al. Prognostic value of coronary electron-beam computed tomography for coronary heart disease events in asymptomatic populations. Am J Cardiol. 2000;85:945-948. 2) Koenig W, Sund M, Frohlich M, et al. C-reactive protein, a sensitive marker of inflammation, predicts future risk of coronary heart disease in initially healthy middle-aged men:results from the MONICA. Circulation 1999;99:237-242. 3) Ridker PM, Hennekens CH, Buring JE, et al. C-reactive protein and other markers of inflammation in the prediction of cardiovascular disease in women. N Engl J Med. 2000;342:836-843. 4) Danesh J, Whincup P, Walker M, et al. Low grade inflammation and coronary heart disease: prospective study and updated meta-analyses. BMJ. 2000;321:199-204. 5) Le T, Wong N, Detrano R, et al. The relationship between clinical coronary events and coronary artery calcium as detected by electron beam computed tomography in diabetes. Diabetologia 1999;42:A231.

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