1. Use of OCT to Localize Macrophages
Ik-Kyung Jang, MD, PhD
Professor of Medicine
Harvard Medical School

2. Disclosure Research grant: LLI/St
Disclosure Research grant: LLI/St. Jude medical, Medtronic, Abbott Vascular, JNJ Consultant: LLI/St. Jude medical

3. Macrophages by OCT
Stable Angina
Post-MI T LP LP
Lumen

4. Ex Vivo Macrophage Study
Low Mf
High Mf
250 µm
OCT
CD68

5. Linear NSD vs. CD68 CD68 % area > 10 % - NSD cutoff 6.2% SENS
100% (70-100%)
SPEC
100% ( %)
Tearney. Circulation, 2003

6. Macrophage Analysis (119 plaques)
Cap segmentation-
Entire fibrous cap
Rupture
Surface: < 50 µm from lumen
Subsurface: > 50 µm from lumen
NSD computation-
Definition:
Macrophage Density ~ Mean NSD
within Segmented Region 0%
10%

7. Tissue Property Analysis

8. Tissue Property Analysis

9. Evaluation of Macrophage in Patients
Macrophage density ~ clinical syndrome
Rupture vs. non-rupture site density
Surface vs. subsurface density

10. Macrophage Density Clinical Presentations*
*P < 0.001

11. Macrophage Density Culprit vs. Remote Sites

12. Macrophage Density Rupture Sites

13. Macrophage Density Surface versus Subsurface
Culprit
Remote
Surface
AUC = 0.79
Subsurface
AUC = 0.69
P = 0.035
Surface
AUC = 0.73
Subsurface
AUC = 0.72
P = 0.80
Surface cap macrophage density is more predictive of clinical syndrome than subsurface macrophage density at culprit, but not remote sites

14. Aim of the study
Evaluate the relationships between local plaque fibrous cap macrophage density, the peripheral WBC count, and the plaque characteristics

15. Correlation of WBC count with Macrophage Density and Fibrous Cap Thickness
16.0
14.0
12.0
10.0
8.0
6.0
4.0
WBC count
2.0
0.0
Macrophage Density (%)
5.5
5.0
4.5
3.5
3.0
2.5
Fibrous Cap Thickness (Ln)
r = , p < 0.001
r = , p < 0.013

16. Association Between Macrophage Density and Fibrous Cap Thickness
10.0
8.0
6.0
4.0
2.0
5.5
5.0
4.5
3.5
3.0
2.5
Ln of Fibrous Cap Thickness

17. Macrophage Density Non TCFA vs TCFA
9.0 A
p < 0.001
8.0
7.0
6.0
5.0
4.0
3.0
5.0 (1.9)
7.4 (1.8)
Non TCFA
TCFA
Values are median (interquartile range)

18. Aim of the study remodeling assessed by IVUS and underlying
Evaluate the association between coronary artery
remodeling assessed by IVUS and underlying
macrophage density identified by OCT

19. Association Between Remodeling and Underlying Plaque Macrophage Density
7.0
6.9
6.0
5.8
Mean Macrophage Density (NSD %)
5.0
4.0
3.9
3.0
Positive
Absent
Negative

20. Summary Macrophage can be detected and localized in vivo.
Increased Macrophage density in ACS.
Correlation between macrophage density and plaque characteristics (TCFA) and systemic inflammation (WBC).
Correlation between macrophage density and positive remodeling.

21. Limitations
The difference in macrophage density is marginal.

22. Limitations The difference in macrophage density is marginal.
Enzymatic activity of macrophage is not known.
Measuring NSD, not macrophage.
4. Prognostic utility is unknown.