Researchers compare clinical outcome of patients with smaller and larger AAAs after EVAR

Patients with abdominal aortic aneurysms (AAAs) of less than 5.5 cm have no significant differences in clinical outcomes after endovascular repair (EVAR) than those with larger AAAs according to data from a five-year prospective clinical trial setting. The researchers maintain their recommendation that small aneurysms should not be treated surgically. Details of this study were presented at the 64th Vascular Annual Meeting presented by the Society for Vascular Surgery.

Researchers from the Washington University School of Medicine in St. Louis reported data from a subgroup analysis of the prospective Metronic Talent Enhanced Low Profile System trial. There were no statistically significant differences in the rate of freedom from major adverse events (84.6% versus 75.8%) or freedom from aneurysm-related mortality (98.7% versus 96.8%) at one year. Long term outcomes at 5 years also showed no difference.

Jeffrey Jim, MD, a fellow from the Section of Vascular Surgery, said that 156 patients enrolled in the prospective Metronic Talent Enhanced Low Profile System trial were evaluated. Analyses were performed for patients with AAAs that measured less than 5.5 cm and for those with AAAs larger than 5.5cm. Demographics, aneurysm morphology, and perioperative endpoints were assessed. Safety and effectiveness endpoints were evaluated at 30 days, one year, and five years after the procedures.

"All patients in the study (85 small AAAs and 71 large) had similar age, gender and medical risk profile," said Dr. Jim. "However, there were anatomic differences between the two group with the aortic neck in small AAA patients being longer (24.7 mm vs 20.7 mm), less angulated (27.20 vs 34.20) and smaller (24.6 mm vs 26.1 mm). In terms of perioperative outcomes, the two groups were very similar with the only difference being the small AAA patients spent less time in the intensive care unit (8.1 hours vs 26.3 hours). The small AAA patients also had higher rate of successful aneurysm treatment at 12 months (96.8% vs 84.9%) as defined by the study as the combination of technical success, absence of aneurysm expansion, and absence of reintervention for type I or type III endoleaks."

Dr. Jim added that there were no other statistically significant differences during the perioperative period or any other effectiveness endpoints at 12 months. There were also no differences in rates of migration, endoleaks, change in aneurysm diameter or freedom from aneurysm-related mortality at 5 years.

"We even did further subgroup analyses by separating groups by AAA centimeter size: 55 patients with very small (less than 5 cm), 30 with small (5.1-5.4 cm); and 71 with larger (more than 5.5 cm). The findings were similar to our original comparison," said Dr. Jim. "The data from this study is unique in that it comes from a prospective 5-year clinical trial. The results confirm the intuitive notion that smaller AAAs have aortic neck characteristics that are more favorable for EVAR. However, the important take home message is that there were no differences in long-term 5-year outcomes between the two groups. So our position remains that EVAR should not be routinely recommended for those with small AAAs."