The 301 Classification: A Proposed Modification to the Stanford Type B Aortic Dissection Classification for Thoracic Endovascular Aortic Repair Prognostication

Objective To assess the usefulness of a modified Stanford classification for risk stratification of complications after thoracic endovascular aortic repair (TEVAR) for type B aortic dissection (TBAD). Patients and Methods This retrospective analysis included 201 patients from an observational multicenter cohort study who underwent TEVAR for TBAD from January 1, 2011, to December 31, 2016. The patients were divided by using a modified Stanford classification, termed 301, into 3 groups: types B1 (n=62) and B3 (n=24), with a true and false lumen, respectively, descending closely along the thoracic vertebral bodies, and type B2 (n=115), a semi-spiral or spiral configuration. The value of the 301 classification in assessing the risk for post-TEVAR thoracic aortic expansion, as main outcome, and other complications was assessed by using the Kaplan-Meier method and multivariable Cox proportional hazards models. Results Median follow-up duration was 26.37 months, and the 24-month cumulative rate of freedom from thoracic aortic enlargement was 0.58 (95% CI, 0.25 to 0.81) for type B3, 0.75 (95% CI, 0.64 to 0.83) for type B2, and 0.97 (95% CI, 0.88 to 0.99) for type B1. In the multivariable Cox regression models, types B2 and B3 with type B1 as reference were independently associated with the risk for thoracic aortic expansion (type B2: hazard ratio, 7.81; 95% CI, 1.84 to 33.13; type B3: hazard ratio, 13.91; 95% CI, 2.86 to 67.69). Conclusion The 301 classification, a modified Stanford classification system in the era of endovascular repair, appears to improve the risk stratification of patients with TBAD undergoing TEVAR. Trial Registration Chinese Clinical Trial Registry number: ChiCTR-POC-17011726.