Meta-analysis of peak wall stress in ruptured, symptomatic and intact abdominal aortic aneurysms

Background: Abdominal aortic aneurysm (AAA) is an important cause of sudden death; however, there are currently incomplete means to predict the risk of AAA rupture. AAA peak wall stress (PWS) can be estimated using finite element analysis (FEA) methods from computed tomography (CT) scans. The question is whether AAA PWS can predict AAA rupture. The aim of this systematic review was to compare PWS in patients with ruptured and intact AAA. Methods: The MEDLINE database was searched on 25 May 2013. Case-control studies assessing PWS in asymptomatic intact, and acutely symptomatic or ruptured AAA from CT scans using FEA were included. Data were extracted independently. A random-effects model was used to calculate standard mean differences (SMDs) for PWS measurements. Results: Nine studies assessing 348 individuals were identified and used in the meta-analysis. Results from 204 asymptomatic intact and 144 symptomatic or ruptured AAAs showed that PWS was significantly greater in the symptomatic/ruptured AAAs compared with the asymptomatic intact AAAs (SMD 0.95, 95 per cent confidence interval 0. 71 to 1.18; P < 0. 001). The findings remained significant after adjustment for mean systolic blood pressure, standardized at 120 mmHg(SMD 0.68, 0.39 to 0.96; P < 0. 001). Minimal heterogeneity between studies was noted (I-2 = 0 per cent). Conclusion: This study suggests that PWS is greater in symptomatic or ruptured AAA than in asymptomatic intact AAA.