RS17 - Pre-induction and Post-discharge Venothromboembolism Chemoprophylaxis Should Be Considered in Patients After Vascular Major Open Abdominal Procedures

Objectives: Venous thromboembolism (VTE) is a significant morbidity following open major abdominal surgery. Whereas there is clear guidance for pre-induction VTE prophylaxis in general surgery population, there is none in vascular population because of the belief that intraoperative therapeutic heparin should prevent VTE. Although most vascular patients receive VTE prophylaxis while in hospital, post-discharge VTE prophylaxis is common practice. We investigate incidence of VTE after open major vascular compared to open general surgery cases, particularly pattern of in-hospital and post-discharge VTE to determine whether the current practice should be adjusted.

Methods: Two populations of open major abdominal surgery were compared in the ACS-NSQIP database from 2011 - 2021: vascular and general. Vascular cases were identified using targeted database for open abdominal aortic aneurysm and open aortoiliac disease and general cases were identified using CPT codes for open enterectomy, gastrectomy, colectomy, hepatectomy, pancreatectomy and nephrectomy. There were significant preoperative differences between the two groups which we accounted for using 1:1 propensity matching. 30-day outcomes were studied.

Results: After propensity matching, there were 13,093 cases of vascular and 13,196 cases of general open major abdominal surgery. There was no difference in 30-day mortality, MACE, pulmonary, renal, sepsis or length of stay. VTE rate was significantly lower in vascular cases compared to general cases (1.31% vs. 3.02%, aOR 0.4266, p < 0.0001). In the vascular population, patients with VTE were associated with higher mortality (aOR 0.5888, p= 0.0283), MACE (aOR 0.4360, p < 0.0001), pulmonary (aOR 0.2058, p < 0.0001), renal dysfunction (aOR 0.5501, p=0.02), sepsis (aOR 0.2523, p < 0.0001), and length of stay greater than 7 days (aOR 0.256, p < 0.0001). Mean time from OR to VTE occurrence was 10.52 +/- 7.14 days. VTE occurrence showed a bimodal distribution with 77% of VTE occurring in early period ( < 14 days) and 23% occurring in late period (>14 days) (Figure I). 78% of VTE developed in-hospital while 22% developed post-discharge.

Conclusions: VTE is lower in vascular compared to general surgery cases, however 1.31% is still a significant number and given the mortality and morbidity associated with VTE, pre-induction VTE prophylaxis should be strongly considered. Although a majority of VTE occurred in hospital, a cohort of patients develop VTE in the late postoperative period with 22% of patients developing VTE post-discharge, suggesting that post-discharge VTE prophylaxis should be considered in selective high-risk vascular patients.