Objectives: Type B aortic dissection (TBAD) requires complex surgical or endovascular treatment in a subset of patients. Whether the hospital caseload or vascular surgery specialization affects perioperative outcomes remains unclear. This study evaluated the association of annual hospital volume and vascular surgery specialization with in-hospital mortality after TBAD treatment in Germany. Methods: We performed a nationwide retrospective analysis of German Diagnosis-Related Group hospital episode data from 2010 to 2023. All patients surgically or endovascularly treated for TBAD were identified using International Statistical Classification of Diseases and Related Health Problems, 10th revision, German Modification and procedural (Operations and Procedures Code) codes. Hospitals were stratified into four annual caseload categories (<= 5, 6-10, 11-20, and >20 cases). The primary outcome was the in-hospital mortality rate; the secondary outcomes included major perioperative complications. Multilevel logistic regression (random intercepts for hospital and year) was performed to assess the association of the hospital volume and vascular surgery specialization of the treating surgeon with mortality, with adjustment for demographics, comorbidities, and treatment modality. Results: A total of 18,400 patients with treated TBAD were identified. Very-high-volume hospitals (>20 cases/year) treated 36.9% of all patients, and low-volume hospitals (<= 5 cases/year) accounted for 67.4% of the treating institutions but only for 22.3% of the procedures. Overall, the in-hospital mortality rate was 9.1%, decreasing from 10.1% in lowvolume to 7.8% in very-high-volume hospitals. In risk-adjusted analyses, low- and medium-volume hospitals had significantly higher in-hospital mortality rates (odds ratio [OR], 1.30; 95% confidence interval [CI], 1.05-1.60; P = .016 and OR, 1.32; 95% CI, 1.06-1.64; P = .013, respectively, vs very-high-volume hospitals), and treatment in vascular surgery departments was associated with reduced in-hospital mortality (OR, 0.44; 95% CI, 0.36-0.54; P < .001). Conclusions: Higher hospital caseload and vascular surgery specialization were independently associated with improved in-hospital survival after TBAD treatment. The findings support the centralization of complex aortic care and emphasize that both the procedural volume and dedicated vascular expertise contribute to optimal outcomes.
