ATAAD Repair Outcomes Based on Surgeon Experience and Center Volume

Acute Type A Aortic Dissection (ATAAD) repairs performed by a low-volume aortic team are significantly associated with increased mortality compared to ATAAD repairs involving a more experienced surgeon, new study results suggest.

“Previous studies have suggested better outcomes when acute Type A aortic dissections are repaired at high-volume aortic centers,” said Juan Umana-Pizano, MD, of the University of Texas Health Science Center at Houston during his presentation at the 65^th Annual Meeting & Exhibition of the Southern Thoracic Surgical Association. “However, it is unclear whether these outcomes are due to inherent possible resources or individual surgeon experience.”

Umana-Pizano and colleagues evaluated data on 553 ATAAD repairs at a single institution between 1999 and 2016. Surgeons were classified as either high-volume (HVAS, two surgeons, cases ≥ 30) or low-volume (LVAS, five surgeons, cases < 30). Roles were also taken into consideration, such as primary surgeon versus first assistant. Researchers conducted analyses based on HVAS in both primary and first assistant roles, one HVAS with one LVAS, and LVAS in both primary and first assistant roles.

Mean experience for HVAS was 238 cases, compared to 12 cases for LVAS. In 91% of operations, at least one HVAS was present. Most cases were done with a HVAS in the primary role and an LVAS assisting. When a HVAS was present, in-hospital mortality was 15%, compared to 22% with an all LVAS team (P = 0.31).

Mean patient ages were 63 years for HVAS primary and assistant, 57 years for HVAS primary LVAS assistant, 64 years for LVAS primary HVAS assistant, and 55.5 years for LVAS primary and assistant. More than half of patients were male across study groups. The groups did not differ significantly in weight, arterial hypertension, diabetes, chronic obstructive pulmonary disease, and preoperative cardiac arrest. The all-HVAS group had a higher rate of coronary artery disease, aortic rupture, and cardiovascular disease, but these risk factors were not statistically significant, Umana-Pizano said.

“Interestingly, the time from admission to surgery was higher in the all-HVAS surgery group versus the all-LVAS surgery group,” Umana-Pizano said.

The authors reported no postoperative differences in reoperation, readmission, or postoperative stroke. ICU and hospital length of stays did not differ between groups. When adjusting for preoperative factors, the LVAS team had a twofold (2.1) mortality risk (P = 0.047). For the HVAS group, expected risk for 30-day mortality was 16%, compared to 13% in the LVAS group (P < 0.02).

In the study abstract, the researchers speculated that “[i]mproved outcomes seen at high-volume aortic valve centers may be predominantly due to surgeon experience and not from inherent resources available at high-volume centers,” and added that the present study “may also have implications on call coverage for ATAAD repair.”

The presentation led to a discussion about the presence of high-level surgeons for lower-level procedures, as well as how well residents are trained for certain operations and whether there should be a dedicated staff for specific surgeries. One attendee commented that Type A dissection is widely considered one of three procedures residents should be able to do when they complete their residency, as the operation is often performed in the middle of the night, when a senior partner may not be available to come help.

“If it’s during the day, your senior partner’s doing four microvalve repairs,” the attendee said. The solution, then, is to make sure residents are trained to do it. There’s no resident that should leave a program not being able to do a Type A dissection,” he said, adding it must be done safely.