New techniques for the “invasive diagnosis” of the vulnerable plaque

1. New techniques for the“invasive diagnosis” of the vulnerable plaque Antwerp, 17 March 2006

2. “Invasive” diagnosis “Non-invasive” diagnosis Biomarkers History Platelets Stress/ Viability Tests Coagulation factors

3. DEFINITIONS Vulnerable plaques (or high-risk plaques or thrombosis-prone plaques): • Thin- cap fibro-atheroma:65% of all vulnerable plaques,lipid core >40% of total plaque,fibrous cap <100 μm. • Erosion: 30% of all vulnerable plaques,erosion/loss of dysfunctional endothelium. • Calcific nodule: 5% of all vulnerable plaques.

5. Normal Coronary artery During decades can develop Asymptomatic atherosclerosis During years can lead to Vulnerable plaques Can progress, in an unpredictable way, to Plaques that develop thrombosis Can conduct to Acute coronary syndromes Asymptomatic progression Stenosis progression and stable angina symptoms

6. NO RELATIONSHIP BETWEEN STENOSIS SEVERITY AND VULNERABILITY

7. “Standard” techniques Coronary angiography

8. “Standard” techniques Coronary angiography

9. “Standard” techniques • Angiographicallycomplex plaques: • Contrast present outside the lumen borders (ulceration) • - Irregular and undermined borders (plaque rupture) • - Intracoronary filling defect (thrombosis) Coronary angiography • Issues: • Visualization of the coronary lumenonly • Often these plaques are already “flow-limiting” • Complex plaques = vulnerable plaques already at advanced stage!

10. Around 70% of acute coronary occlusions occurs in angiographically “normal” areas

11. “Standard” techniques IVUS

12. “Standard” techniques IVUS Axial resolution: 150 μm Lateral resolution: 300 μm Morphologic data on the plaques Echogenicity echo-lucent plaques echo-dense plaques shadow behind calcium Discrete sensitivity (70%) ed high specificity (90%) for calcifications Low sensitivity (50%) e specificity (30%) for lipid “core” No information regarding fibrous cap (low resolution!!)

13. “Standard” techniques IVUS • The majority of available data comes from retrospectivestudies in patients with knownCAD. • In UA patients as compared to SA patients: • The presence of ruptured plaques is more frequent • There are plaques with larger echo-lucent areas • There is more frequently a positive “remodeling”

14. Several studies have shown the presence of multiple plaque ruptures in the coronary tree, and most of them were ASYMTOMATIC!

15. VIRTUAL HISTOLOGY

16. Amplitudee Frequency are used to reconstruct the image

19. Unstable Angina Recent myocardial infarction

20. Stable Angina

21. Pull-back

22. ELASTOGRAPHYPALPOGRAPHY

30. Diffuse and severe concentric calcification

33. Other techniques… Measures the intensity of reflected light, as IVUS measures ultrasounds Optical Coherence Tomography (OCT) Quality: - high resolution (20 μm) Defects: - Bulky devices with very large diameter - need for “removal” of blood (occlusive balloon proximal or continuos flushing with water)

34. Fibrous Tissue = “signal-rich” Calcium = “signal-poor” with well defined contours Endoluminal Thrombosis Lipid Tissue = “signal-poor” with hazy contours

35. Thermography Other techniques… • - Measures the difference in temperaure between a “baseline” area and a “region of interest” • Index of the inflammatory status of the atherosclerotic plaque • Most clinical studies performed to date only in one center (Greece) • “Cool-down” effect of blood

36. Other techniques… Thermography

37. A glimpse into the future… • Absence of a reliable animal model of vulnerable plaque • Need for prospective studies (PROSPECT, VIP) • Pan-coronary inflammation syndrome • “Push” from pharmaceutical companies and interventional cardiologists • Every technique offers data on one aspect of the vulnerable plaque more techniques togheter?

38. For further slides on these topics please feel free to visit the metcardio.org website:http://www.metcardio.org/slides.html