Predictive Value of Imaging-Based Classifications for Conservative Management Failure in Isolated Superior Mesenteric Artery Dissection

BACKGROUND: Isolated superior mesenteric artery dissection (ISMAD) is a relatively uncommon vascular disease with uncertain optimal management. Multiple imaging-based classifications have been developed, but their ability to predict conservative management failure remains unclear. OBJECTIVES: This study aimed to compare the predictive performance of 8 ISMAD classification systems for conservative management failure. METHODS: This multicenter retrospective study included 156 patients with ISMAD from 3 centers in China (October 2009 to February 2023). The median computed tomography angiography follow-up time was 7.9 months (IQR: 3.7-24.3). Patients were classified using 8 systems and grouped as successful (108 of 156, 69.2%) or failed (48 of 156, 30.8%) conservative management. Performance was evaluated by model fit (Akaike Information Criterion, Bayesian Information Criterion), discrimination (C-statistic), net reclassification improvement, calibration, and decision curve analysis. RESULTS: Compared with the successful group, patients who failed conservative management had a longer duration of abdominal pain before admission (8 [IQR: 3-30] days vs 4 [IQR: 1-11] days; P = 0.0214) and more severe superior mesenteric artery degree of stenosis (0.83 [IQR: 0.69-1.00] vs 0.64 [IQR: 0.52-1.00]; P = 0.00544). Among all classifications, Tan's classification showed good model fit (Akaike Information Criterion = 186; Bayesian Information Criterion = 226), the highest discrimination (C-statistic = 0.750; 95% CI: 0.670-0.830), and the greatest improvement (net reclassification improvement = 0.593; 95% CI: 0.244-0.903). It also demonstrated good calibration and yielded the highest net benefit across clinically relevant threshold probabilities in decision curve analysis. CONCLUSIONS: Tan's classification showed the best overall performance in predicting conservative management failure and may help guide timely interventions.