Abstract 417: Normalized Wall Index Predicts New Fibrous Cap Rupture and New Intraplaque Hemorrhage in the Carotid Atherosclerotic Lesion
Purpose: We sought to determine the prevalence, incidence and predictors of fibrous cap (FC) rupture and intraplaque hemorrhage (IPH) in the carotid artery.
Methods: 108 asymptomatic individuals (male: 89.0%; age: 70.7±9.3 yrs) with 50–79% carotid stenosis by duplex ultrasound were imaged with a 1.5T MRI protocol at baseline and 3 years. At baseline, all participants filled out a healthcare questionnaire and underwent phlebotomy. At each matched axial location between time points, two reviewers blinded to temporal and clinical data reached a consensus interpretation of each scan and measured the lumen area, wall area, total vessel area, and normalized wall index (NWI = wall area/total vessel area). Area measurements of calcification and lipid-rich necrotic core and the presence or absence of IPH and FC rupture were also recorded. Multiple logistic regression analysis was used to determine associations and predictors of FC rupture and IPH from each of the arterial, clinical and serological metrics.
Results: At baseline, FC rupture was present in 23 (21.3%) participants and IPH was present in 27 (25.0%) participants. Amongst all variables, mean arterial NWI (particularly NWI ≥ 0.56) had the strongest association with the presence of FC rupture and IPH (Table 1⇓). During the 3-year period of observation, a new FC rupture occurred in 9 of 85 (10.7%) subjects and a new IPH occurred in 7 of 81(8.6%) subjects. Amongst all variables, mean arterial NWI (particularly NWI > 0.56) was the strongest predictor of a new FC rupture and a new IPH (Table 1⇓). For comparison, we include results in Table 1⇓ for the prediction of new FC rupture and new IPH using minimum lumen area.
Conclusions: NWI, a measure of plaque burden severity, is the strongest predictor of new FC rupture and new IPH in the carotid artery. NWI may be a key marker in determining present and future plaque vulnerability.