Aneurysm sac expansion is independently associated with late mortality in patients treated with endovascular aneurysm repair.

BACKGROUND

Patients undergoing endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms can exhibit variations in sac behavior ranging from complete regression to expansion. We evaluated the impact of sac behavior at 1-year follow-up on late survival.

METHODS

We used the Vascular Study Group of New England (VSGNE) registry from 2003 to 2011 to identify EVAR patients with 1-year computed tomography follow-up. Aneurysm sac enlargement ≥5 mm (sac expansion) and decrease ≥5 mm (sac regression) were defined per Society for Vascular Surgery guidelines. Predictors of change in sac diameter and impact of sac behavior on long-term mortality were assessed by multivariable methods.

RESULTS

Of 2437 patients who underwent EVAR, 1802 (74%) had complete 1-year follow-up data and were included in the study. At 1 year, 162 (9%) experienced sac expansion, 709 (39%) had a stable sac, and 931 (52%) experienced sac regression. Sac expansion was associated with preoperative renal insufficiency (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.5-8.0; P < .01), urgent repair (OR, 2.7; 95% CI, 1.4-5.1; P < .01), hypogastric coverage (OR, 1.7; 95% CI, 1.1-2.7; P = .02), and type I/III (OR, 16.8; 95% CI, 7.3-39.0; P < .001) or type II (OR, 2.9; 95% CI, 2.0-4.3; P < .001) endoleak at follow-up, and sac expansion was inversely associated with smoking (OR, 0.6; 95% CI, 0.4-0.96; P = .03) and baseline aneurysm diameter (OR, 0.7; 95% CI, 0.6-0.9; P < .001). Sac regression (vs expansion or stable sac) was associated with female gender (OR, 1.8; 95% CI, 1.4-2.4; P < .001) and larger baseline aneurysm diameter (OR, 1.4; 95% CI, 1.2-1.5; P < .001) and inversely associated with type I/III (OR, 0.2; 95% CI, 0.1-0.5; P < .01) or type II endoleak at follow-up (OR, 0.2; 95% CI, 0.2-0.3; P < .001). After risk-adjusted Cox regression, sac expansion was independently associated with late mortality (hazard ratio, 1.5; 95% CI, 1.1-2.0; P = .01), even with adjustment for reinterventions and endoleak during follow-up. Sac regression was associated with lower late mortality (hazard ratio, 0.6; 95% CI, 0.5-0.7; P < .001). Long-term survival was lower (log-rank, P < .001) in patients with sac expansion (98% 1-year and 68% 5-year survival) compared with all others (99% 1-year and 83% 5-year survival).

CONCLUSIONS

These data suggest that an abdominal aortic aneurysm sac diameter increase of at least 5 mm at 1 year, although infrequent, is independently associated with late mortality regardless of the presence or absence of endoleak and warrants close observation and perhaps early intervention.