Acute Aortic Occlusion: A Nationwide Cohort Study

Abstract

Introduction: Acute aortic occlusion (AAO) is a rare and potentially catastrophic event. The aim was to extend the understanding of this condition, and to study time-trends and long-term survival. Methods: A well validated nationwide vascular database, where patients had been entered prospectively, was used to identify the cases, and a cross-link to the Population Registry to study long-term survival. Results: During the 21-year study-period (1994-2014), 715 patients had been treated for AAO with a yearly incidence of 3.7 per million inhabitants. Mean age was 69.7 years, 50.5% were women and mean follow-up was 5.2 years. The aetiology for AAO was in-situ thrombosis in 458 patients (64.1%), saddle embolus in 152 (21.3%), and occluded grafts/stents/stentgrafts in 105 (14.7%). The proportion of occluded grafts/stents/stentgrafts increased during the study period with a simultaneous reduction in the proportion of in-situ thrombosis, the proportion of saddle embolus was relatively unaltered over time. Grafts/stents/stentgrafts were occluded after a mean of 39.2 months from initial surgery. Most patients (81.2%) presented with bilateral acute limb ischaemia. The most commonly used methods for revascularization were thrombo-embolectomy (32.0%), thrombolysis (22.4%), axillary-bifemoral bypass (18.9%) and aorto-biilical/bifemoral bypass (18.2%). The choice of revascularization technique depended on the aetiology of the occlusion. Amputation was required in 8.6% of the cases and 19.9% of the patients died within the first month after surgery. The 30-days mortality rate was lower after occluded grafts/stents/stentgrafts (9.5%) and higher in the saddle embolus group (30.9%, p<0.001). There was a reduction in overall 30-days mortality over time (25.0% 1994-2000 versus 15.3% 2008-2014, p=0.008). There were significant differences in survival between the subgroups, depending on aetiology, throughout the follow-up, although the difference occurred early after the event (log-rank, p<0.001, see the attached Figure). Conclusion: Mortality after AAO is high, but improving over time. The proportion of AAO secondary to occluded grafts/stents/stentgrafts increases, and the proportion secondary to native artery thrombosis decreases, over time.