Preemptive aneurysm sac embolization for infrarenal endovascular aneurysm repair

Aneurysm sac behavior has been associated with long-term survival and reinterventions, spurring an interest in more active management of the aneurysm sac during endovascular aortic repair (EVAR). We therefore investigated the utility of sac embolization with shape memory polymer (SMP) plugs (Shape Memory Medical), a novel, biodegradable, nonartifact-producing implant inserted into the aneurysm sac between the graft and vessel wall to promote sac thrombosis and regression.

We retrospectively studied all patients undergoing EVAR of infrarenal aneurysms at two centers from February 2022, to January 2024, where SMP plugs were used. Safety outcomes included inadvertent embolization and sac perforation during manipulation. Efficacy outcomes were volume and diameter changes, as well as endoleaks, and reinterventions using TeraRecon radiologic software.

There were 29 patients who underwent EVAR with SMP plugs during the study period who had 1-year imaging data available for review. The mean age was 77 years (standard deviation, 8.8 years), and 72% were men. Preoperative median total aneurysm volume was 98 mL (interquartile range [IQR], 80-157 mL), and median preoperative blood lumen volume was 70 mL (IQR, 58-96.7 mL), with 62% patent inferior mesenteric arteries and one accessory renal artery. The median number of plugs used per patient was 90 (IQR, 51-130). The most frequently used grafts were the Gore Excluder (n = 23) and Cook Zenith (n = 6), with four iliac branch devices, five hypogastric coil covers, and Aptus Endoanchors in one patient. At 1 year, there were no patients with evidence of endoleak, no reinterventions, no adverse safety events during the procedure, and no perioperative deaths. The median percentage change in aneurysm volume at 1 year was 17% regression (IQR, 7%-33%), and the median change in aneurysm diameter was 6 mm regression (IQR, -10 mm to -1 mm). By diameter at 1 year postoperatively, 55% of patients (n = 16) demonstrated regression, 45% of patients (n = 13) demonstrated stability, and there were no patients with expansion. In volume analysis, 67% of those patients who regressed showed >10% regression in aneurysm volume.

Preemptive aneurysm sac embolization at the time of EVAR is a safe and effective method of inducing sac thrombosis. At 1-year follow-up, patients have demonstrated high rates of sac regression, no endoleaks, and no need for reintervention. The SMP plugs hold promise over other coil or liquid embolic methods as they are biodegradable, and do not produce significant artifact on computed tomography scan. Longer-term data are needed to confirm these outcomes; however, 1-year postoperative outcomes continue to demonstrate promise.