High-Resolution MRI-Derived Carotid Plaque Feature for Long-Term Cardiovascular Risk Stratification After Carotid Revascularization: The Role of Intraplaque Hemorrhage

Purpose: To evaluate the prognostic value of carotid plaque features derived from high-spatial-resolution vessel-wall MRI (HR-MRI) for long-term major adverse cardiovascular events (MACE) after carotid revascularization. Methods: Consecutive patients undergoing carotid revascularization between April 2017 and April 2024 with preoperative carotid HR-MRI were included. Ipsilateral intraplaque hemorrhage (IPH) was identified as a hyperintense plaque component on SNAP images and manually segmented on each relevant slice using Vessel Explorer 2.0 software. IPH volume was calculated as the sum of the segmented IPH areas multiplied by slice thickness. MACE comprised cardiovascular death, nonfatal myocardial infarction, coronary revascularization, and stroke. Associations were assessed using Cox regression and Kaplan–Meier analysis. Prediction models were evaluated using the concordance index (C-index), calibration, and decision curve analysis (DCA). Results: Among 296 patients (mean age 65.04 ± 9.47 years; 244 82.4% men), 154 underwent carotid endarterectomy (CEA) and 142 underwent carotid artery stenting (CAS). During a median follow-up of 4.5 years, ipsilateral IPH volume was an independent predictor of MACE in the overall cohort (hazard ratio HR, 1.49; 95% confidence interval CI, 1.34-1.66; P < .001), as well as in the CEA subgroup (HR, 1.31; 95% CI, 1.11-1.55; P = .001) and CAS subgroup (HR, 1.21; 95% CI, 1.05-1.40; P = .007). Contralateral IPH was also independently associated with higher event risk in the overall cohort (HR, 2.37; 95% CI, 1.34-4.19; P = .003) and in both procedural subgroups (CEA: HR, 2.79; 95% CI, 1.16-6.67; P = .022; CAS: HR, 2.47; 95% CI, 1.22-5.00; P = .012). Kaplan–Meier analysis showed significantly lower event-free survival in patients with ipsilateral or contralateral IPH. Prediction models demonstrated acceptable discrimination (C-index: overall, 0.725; CEA, 0.755; CAS, 0.711), good calibration, and consistent clinical net benefit. Conclusions: Among HR-MRI–derived carotid plaque features, ipsilateral IPH volume and the presence of contralateral IPH were independently associated with long-term cardiovascular events after carotid revascularization. These findings support carotid IPH as an imaging marker of systemic atherosclerotic vulnerability and may improve individualized risk stratification after revascularization.