In-Depth Patient-Level Analysis of Pathological Events in Patients Not Surviving Open AAA Repair: Results from the ACTION-1 Randomized Controlled Trial

Background Elective repair for an abdominal aortic aneurysm (AAA) is performed to prevent rupture and subsequent death. The risk of early mortality is higher after open repair than after endovascular repair and needs to be reduced. Registries lack granular individual data to investigate this increased mortality. An independent, detailed, patient-level analysis of the international randomized controlled ACTION-1 trial was performed to investigate the relation between thromboembolic, hemorrhagic, or other events with mortality after open AAA repair, thereby exploring the cascade of pathological events leading to death. Methods An adjudication committee was installed to assess the following domains: attributability of thromboembolic or bleeding event, whether the event occurred intraoperative or postoperative, cascade of pathological events, and cause of death. An intraoperative bleeding score was calculated to stratify the severity of bleeding. Results In 16 out of 20 deceased patients (80%), death was attributable to a thromboembolic or bleeding event. Four patients (20%) succumbed to causes unrelated to a thromboembolic or bleeding event. Intraoperative bleeding was the primary cause of death in 4 patients, all of whom underwent activated clotting time–guided heparinization. In contrast, an intraoperative thromboembolic event was the primary cause of death in one patient who had received 5,000 IU of heparin. Conclusion In a randomized controlled trial on 297 patients with open AAA repair, 16 out of 20 (80%) deaths were due to bleeding or thromboembolic events. In most deceased patients, increased perioperative bleeding resulted in a pathological cascade of hypoperfusion, organ failure, and shock. Bleeding and thromboembolic complications must be addressed to reduce mortality after elective open AAA repair.