Using optical coherence tomography and intravascular ultrasound imaging to quantify coronary plaque cap thickness and vulnerability: a pilot study

Table 6 Cap index definition using plaque cap thickness related to plaque vulnerability and AHA plaque classifications

Cap index	Description	AHA type	Description	Vulnerability level
0	No component	Type I or Type II	Normal or slight intimal thickening	Very stable
1	Minimum cap thickness > 200 µm	Type III	Moderate intimal thickening, no extracellular lipid, calcification or significant inflammation	Stable
2	150 µm < minimum cap thickness ≤ 200 µm	Type IV, Vb and Vc	Small lipid core (< 30% of plaque size); calcification may be present; thick fibrous cap(> 150 μm);	Slightly unstable
3	65-m < min cap thickness ≤ 150 µm	Type Va	Moderate lipid core(30–40% of plaque size) and fibrous cap(65–200 μm); moderate intraplaque hemorrhage and inflammation	Moderately unstable
4	Min cap thickness ≤ 65 µm	Type VI	Large lipid core(> 40%); thin fibrous cap(< 65 μm); large intraplaque hemorrhage; extensive inflammation; previous plaque rupture	Highly unstable

ISSN: 1475-925X