Background:
High risk plaque accounts for the majority of acute coronary events. Low endothelial shear stress (ESS) is a key factor of the natural history of atherosclerosis. The role of ESS in high risk plaque formation is not well studied in man.
Hypothesis:
To explore the association of low ESS with high risk plaque and to identify the ESS milieu and vascular remodeling response in high risk vs. non high risk plaque.
Methods:
35 coronary arteries from 30 patients were 3D reconstructed with fusion of coronary angiography and optical coherence tomography
(Fig A-D)
. ESS was calculated in the 3D reconstructed arteries using computational fluid dynamics
(Fig E)
and classified into low, moderate and high in 3 mm long segments. In each segment: i) fibroatheromas were classified into high risk and non high risk based on fibrous cap thickness and lipid pool size ii) vascular remodeling was classified into constrictive, compensatory and expansive.
Results:
Fibroatheromas in low ESS segments had significantly thinner fibrous cap compared to high ESS segments (89±84 vs.138±83 μm, p<0.05). Lipid pool size was comparable across all ESS categories. The majority of low ESS segments co-localized with high risk plaques (29 vs. 9%, p<0.05), whereas the majority of high ESS co-localized with non high risk plaques (24 vs. 9%, p<0.05,
Fig F
). Compensatory and expansive remodeling was the predominant remodeling response in low ESS segments containing high risk plaques. In non-stenotic fibroatheromas (expansive or compensatory remodeling) low ESS was predominantly associated with high risk plaques (29 vs. 3%, p<0.05) whereas high ESS was associated with non high risk plaques
(Fig F)
.
Conclusions:
Novel combined anatomic and functional imaging with 3D OCT showed that low ESS and non-constrictive remodeling are associated with high risk plaque in man. Further studies are needed to assess the role of ESS and vascular remodeling in high risk plaque rupture and precipitation of clinical outcomes.
Endothelial Shear Stress
