Table.

Morphological classification of aortic and coronary tissue according to the modified American Heart Association (AHA) classification proposed by Virmani et al¹¹

Subtype of lesion	Abbreviation	Morphological description	Mouse equivalent morphological description
Normal	N	No signs of intimal thickening and intimal inflammation	No signs of intimal thickening and intimal inflammation
Non-progressive intimal lesions
Adaptive intimal thickening	AIT	Natural accumulation of SMCs in the absence of lipid and macrophage foam cells	Absent in murine models
Intimal xanthoma	IX	Superficial accumulation of foam cells without a necrotic core or fibrous cap	Up to several layers of foam cells without a necrotic core or fibrous cap
Progressive atherosclerotic lesions
Pathological intimal thickening	PIT	Plaque rich of SMCs and focal accumulation of extracellular lipids with or without the presence of macrophages	Small extracellular lipid pools with overlying or adjacent located macrophages. Intimal SMCs can be identified.
Early fibroatheroma	EFA	Focal macrophage infiltration into areas of lipid pools with an overlying cap	Larger amounts of extracellular lipid with infiltrating macrophages and cholesterol clefts are visible. The core is shielded from the bloodstream by several layers of SMCs. Variable calcification.
Late fibroatheroma	LFA	Loss of matrix and extensive cellular debris with an overlying fibrous cap. Variable (micro) calcification.	N/A
Vulnerable atherosclerotic lesions
Thin cap fibroatheroma	TCFA	A thin fibrous cap (<65 μm in coronary artery and <155 μm in the aorta) overlying a large necrotic core. Intraplaque hemorrhage can be present in coronary lesions.	N/A
Plaque rupture	PR	Thin cap fibroatheroma with cap disruption with a luminal thrombus communicating with the necrotic core.	N/A
Stabilizing lesions
Healing rupture	HR	Healed lesion composed of SMCs, proteoglycans, and collagen with or without an underlying disrupted fibrous cap. With or without calcifications.	N/A
Fibrotic calcified plaque	FCP	A fibrous lesion with large amounts of calcification without an underlying necrotic core.	N/A

N/A, Not applicable; SMC, smooth muscle cell.