Comparison of Treatment Options for Aortic Necks Outside Standard EVAR Instructions for Use.

INTRODUCTION Endovascular aneurysm repair (EVAR) is associated with worse outcomes in patients whose anatomy does not meet the device instructions for use (IFU). However, whether open repair (OSR) and commercially available fenestrated EVAR (ZFEN) represent better options for these patients is unknown. METHODS We identified all patients without prior aortic surgery undergoing elective repair of abdominal aortic aneurysms with neck length ≥ 4mm at a single institution with EVAR, OSR and ZFEN. We applied device-specific aneurysm neck-related IFU to EVAR patients, and a generic EVAR IFU to ZFEN and OSR patients. Long-term outcomes were studied using propensity scores with inverse probability weighting. We compared outcomes in patients undergoing EVAR by adherence to IFU, and outcomes by repair types in the subset of patients not meeting IFU. RESULTS Of 652 patients (474 EVAR, 34 ZFEN, 143 OSR), 211 had measurements outside of standard EVAR IFU (109 EVAR [23%], 27 ZFEN [80%], and 74 OSR[52%]) . Perioperative mortality was 0.5% overall. For EVAR, treatment outside the IFU was associated with significantly higher adjusted rates of long-term Type IA endoleak (22% at 5 years compared to 2% within IFU, HR 5.8 [3.1-10.9], P<.001), and lower survival (5 and 10 year survival: 56% and 34% versus 81% and 53%, HR 2.3 [1.2-4.3], P=.01). There was no difference in reinterventions or open conversion. In patients not meeting IFU, ZFEN was associated with higher adjusted rates of reinterventions (EVAR as referent: HR 2.6 [1.5 - 4.4], P < .001), while OSR and EVAR patients experienced similar reintervention rates (HR 0.7 [0.4 - 1.1], P = .13). Patients outside the IFU experienced lower mortality with OSR compared to either EVAR (HR 0.4 [0.2 - 0.9], P = .005) or ZFEN (HR 0.3 [0.1 - 0.7], P = .002). When restricted to patients outside the IFU deemed fit for open repair, OSR patients remained associated with lower adjusted mortality compared to ZFEN (HR 0.2 [0.1 - 0.5], P < .001), but statistical significance was lost in the comparison to EVAR (HR 0.6 [0.3 - 1.1], P = .1). CONCLUSION Treatment outside device-specific IFU is associated with adverse long-term outcomes. Open surgical repair is associated with higher long-term survival in patients who fall outside of the EVAR IFU, and should be favored over EVAR or ZFEN in suitable patients. A three-vessel based fenestrated strategy may not be a durable solution for difficult aortic necks, but more data are needed to evaluate the performance of newer, four-vessel devices.