Influence of Oversizing on Outcome in Thoracic Endovascular Aortic Repair

PURPOSE: To investigate the influence of stent-graft oversizing on device-related complications after thoracic endovascular aortic repair (TEVAR) for thoracic aortic aneurysm (TAA). METHODS: The study cohort was composed of patients enrolled in 4 clinical trials of the TAG thoracic stent-graft. A total of 337 TAA patients (222 men; mean age 72 years) treated in these trials had sufficient data for analysis of oversizing and post-procedure mortality and complications, such as endoleak, migration, rupture, and reinterventions. Mean oversizing at the proximal landing zone was 14.6% (range -3.4% to 39.7%). Patients were stratified based on the percentage of oversizing: <10% (n=85, group 1), 10%-20% (n=188, group 2), and >20% (n=64, group 3). RESULTS: Patients in group 1 had significantly larger preoperative proximal aortic diameters (32.6 vs. 31.3 vs. 28.2 mm, respectively; p<0.001) and neck lengths (6.9 vs. 5.8 vs. 5.2 cm (p=0.035). Overall, type I endoleak was the most frequent complication during the first 30 days of follow-up (35, 10.4%), but the incidences did not differ among the 3 groups (10.6% vs. 11.2% vs. 7.8%, respectively; p=0.809). Over a mean follow-up of 41.8±20.7 months, there were no significant differences in the occurrence of device-related complications among the groups, though the incidence of type I endoleaks was lower in group 2 (9.4% vs. 3.2% vs. 7.8%, respectively; p=0.073). Cox proportional hazards modeling showed no difference in the time to type I endoleak among oversizing groups [group 1 vs. 2: HR 1.24, 95% CI 0.65 to 2.36 (p=0.509) and group 3 vs. 2: HR 1.24, 95% CI 0.60 to 2.60 (p=0.562)]. CONCLUSION: The percentage of oversizing did not significantly affect the incidence of device-related complications after TEVAR for TAA. Although oversizing may enhance the radial force and help maintain a good proximal seal, additional oversizing seemed not to improve the overall outcome in this analysis. The current guidelines regarding stent-graft oversizing for TAA seem appropriate, though the correct percentage remains to be determined.