Specialized thoracic aortic team is the next step in improving outcome in acute aortic dissection care

J Thorac Dis 2020;12(10):6112-6114 | http://dx.doi. org/10.21037/jtd-2020-24 In this issue of JTD, Umana-Pizano et al. examined 580 acute type A aortic dissection (ATAAD) cases from 1999 to 2016 at a high-volume centre, and found that there was a 3.72-fold increase in in-hospital mortality by an all lowvolume aortic surgeon (LVAS) team compared to teams with a high-volume aortic surgeon (HVAS), and this increase in mortality extends into 5-year of follow-up (1). HVAS was defined as >10 cases per year, and LVAS was defined as ≤10 cases per year. The study was performed at a high-volume centre where there was no difference in resource allocation to the various team structures examined. The author concluded that the instead of hospital volume, a surgeon’s case-volume may also be an important factor that influences shortand long-term outcome of ATAAD patients. Over the past decade, the surgical mortality of ATAAD decreased significantly from 25% to 18% (2). This improvement in outcome is mainly related to better diagnostic imaging, advances in hypothermic circulatory arrests and cerebral perfusion strategies, increased safety and efficacy of aortic replacement procedures, and perioperative intensive care. However, with an in-hospital mortality of 1 in 5 patients, acute aortic dissection remains a life-threatening condition that is challenging to diagnose and treat. To further improve surgical outcome in patients with type A aortic dissection, centre volume and surgeon case volume have been evaluated. The positive correlation between increased volume of cases and improved surgical outcome for high-risk procedures is well-studied in the literature, and underlies the process of specialization and centralization of complex surgical care (3,4). In cardiac surgery, the volume-outcome relationship has been demonstrated with coronary artery bypass grafting, mitral valve surgery for mitral regurgitation, as well as aortic valve replacement (5-7). In ATAAD, multiple studies have shown that centre volume is one of the strongest predictors of perioperative outcome, and this association remains significant after adjusting for patient factors and co-morbidities (8,9). In a survey of 5,184 patients from the national inpatient sample database from 2003 to 2008, Chikwe et al. found that a strong inverse relationship between operative mortality and both institution and surgeon volume. Surgeons who performed less than 1 aortic dissection repair per year had a mean operative mortality of 27.5%, compared with 17.0% for those averaging 5 or more annually (10). This was similar to the relationship seen between institution volume and mortality: operative mortality was 27.4%in institutions performing 3 or fewer acute aortic dissections a year, compared with 16.4% in those performing more than 13 annually. In practice, regionalization and the utilization of an aortic dissection pathway to a specialized multi-disciplinary aortic dissection team have also been shown to greatly improve post-operative outcome. Recently, a study of 16,886 Medicare beneficiaries looked at whether regionalizing care at high-volume hospitals for ATAADs was associated with lower mortality (11). The authors demonstrated that despite delaying surgery, a regionalization policy that transfers Editorial Commentary