LAUSR

OBJECTIVE Vascular surgeons treating patients with ruptured abdominal aortic aneurysm (rAAA) must make rapid treatment decisions and sometimes lack immediate access to endovascular devices meeting the anatomic specifications of the patient at hand. We hypothesized that endovascular treatment of rAAA (rEVAR) outside manufacturer instructions-for-use (IFU) guidelines would have similar in-hospital mortality compared to patients treated on-IFU or with an infrarenal clamp during open repair (rOAR). METHODS Vascular Quality Initiative (VQI) datasets for endovascular and open aortic repair were queried for patients presenting with ruptured infrarenal AAA between 2013-2018. Graft-specific IFU criteria were correlated with case-specific proximal neck dimension data to classify rEVAR cases as on- or off-IFU. Univariate comparisons between the on- and off-IFU groups were performed for demographic, operative and in-hospital outcome variables. To investigate mortality differences between rEVAR and rOAR approaches, coarsened exact matching was used to match patients receiving off-IFU rEVAR with those receiving complex rEVAR (requiring at least one visceral stent or scallop) or rOAR with infrarenal, suprarenal or supraceliac clamps. A multivariable logistic regression was used to identify factors independently associated with in-hospital mortality. RESULTS 621 patients were treated with rEVAR, with 65% classified as on-IFU and 35% off-IFU. The off-IFU group was more frequently female (25% vs. 18%, p=0.05) and had larger aneurysms (76 vs. 72 mm, p=0.01) but otherwise was not statistically different from the on-IFU cohort. In-hospital mortality was significantly higher in patients treated off-IFU vs. on-IFU (22% vs 14%, p=0.02). Off-IFU rEVAR was associated with longer operative times (135 min vs 120 min, p=0.004) and increased intraoperative blood product utilization (2 units vs. 1 unit, p=0.002). When off-IFU patients were matched to complex rEVAR and rOAR patients, no baseline differences were found between the groups. Overall in-hospital complications associated with off-IFU were reduced compared to more complex strategies (43% vs. 60-81%, p<0.001) and in-hospital mortality was significantly lower for off-IFU rEVAR patients compared to the supraceliac clamp group (18% vs 38%, p=0.006). However, there was no significantly increased mortality associated with complex rEVAR, infrarenal rOAR or suprarenal rOAR compared to off-IFU rEVAR (all P>0.05). This finding persisted in a multivariate logistic regression. CONCLUSIONS Off-IFU rEVAR yields inferior in-hospital survival compared to on-IFU rEVAR but remains associated with reduced in-hospital complications when compared with more complex repair strategies. When compared with matched patients undergoing rOAR with an infrarenal or suprarenal clamp, survival was no different from off-IFU rEVAR. Taken together with the growing available evidence suggesting reduced long-term durability of off-IFU EVAR, these data suggest that a patient's comorbidity burden should be key in making the decision to pursue off-IFU rEVAR over a more complex repair when proximal neck violations are anticipated preoperatively.