# Impact of an emergency department bypass referral pathway for surgically managed Type A aortic dissection diagnosed at non-aortic centers

## TL;DR

A new emergency bypass protocol for aortic dissection patients improves surgical outcomes by reducing delays and mortality.

## Contribution

A regional direct bypass protocol was implemented and shown to improve outcomes for Type A aortic dissection patients.

## Key findings

- Emergency Bypass Group had shorter time from arrival to surgery and lower in-hospital mortality.
- Propensity score matching showed reduced 30-day and in-hospital mortality in the Emergency Bypass Group.
- No significant difference in postoperative complications between the groups.

## Abstract

Surgical outcomes for Type A aortic dissection (TAAD) are significantly improved at high-volume aortic centers. Notably, approximately 60% of TAAD cases treated at these centers are referrals from outside hospitals, with nearly half presenting in an unstable condition upon arrival. To address critical delays in this population, our institution, in collaboration with the Chest Pain Center, implemented a regional Direct Bypass Protocol (DBP) in April 2019. This 24/7 pathway allows patients diagnosed with acute aortic syndrome at non-aortic centers to bypass the emergency department (ED) and proceed directly to surgical care. This study evaluates the impact of the DBP on surgical outcomes for TAAD patients diagnosed at non-aortic centers.

We retrospectively analyzed medical records of TAAD patients diagnosed at non-aortic centers and transferred to our hospital for surgery between January 2018 and December 2023. Clinical outcomes before and after DBP implementation were compared.

The study included 144 patients in the Routine Referral Group and 149 in the Emergency Bypass Group. The two groups were well matched for demographics and comorbidities. Compared to the Routine Referral Group, the Emergency Bypass Group had a significantly shorter time from hospital arrival to surgery (8 h vs. 4 h, p < 0.001) and a higher rate of total arch replacement procedures (84.0% vs. 91.3%, p = 0.059). In-hospital mortality was lower in the Emergency Bypass Group (18.8% vs. 10.7%, p = 0.053). After propensity score matching, both 30-day mortality (12.5% vs. 4.5%, p = 0.031) and in-hospital mortality (15.2% vs. 7.1%, p = 0.056) were significantly reduced in the Emergency Bypass Group. The median hospital stay was also shorter post-matching (16 days vs. 17 days, p = 0.003). There was no significant difference in postoperative complication rates between the groups. Cox regression analysis showed that implementation of the DBP was associated with a reduced risk of mortality (p = 0.002, hazard ratio = 4.546, 95% CI: 1.721–12.004).

A coordinated, point-to-point referral model between the Chest Pain Center and the Aortic Center integrating streamlined pre-hospital triage and a dedicated aortic surgical team significantly improves outcomes for TAAD patients diagnosed at non-aortic centers.