Psoas Muscle Area Predicts All-Cause Mortality After Endovascular and Open Aortic Aneurysm Repair

Abstract

Psoas muscle area (PMA) is a validated surrogate for muscle mass that can be easily measured from a clinical CT scan. This study sought to determine whether PMA was associated with post-operative mortality after endovascular or open aortic aneurysm repair. A retrospective review was undertaken of patients who underwent elective endovascular or open aortic aneurysm repair between 2010 and 2015 at a tertiary vascular center in Montreal, Quebec, Canada. Pre-operative CT scan images were analyzed with the CoreSlicer.com software tool to measure PMA at the axial level of the L4 vertebrae. Measurements were made by two independent observers blinded to clinical data. The primary endpoint was all-cause mortality. The cohort consisted of 149 patients with a mean age of 75.6±8.8 years. The mean PMA was 24.0±5.8cm2 in males, and 14.3±3.1cm2 in females. There were 31 deaths over a mean follow-up of 22.4 months. After adjusting for age, sex, revised cardiac risk index, and surgical approach, Cox regression revealed a graded association between PMA and all-cause mortality with a hazard ratio of 0.86 per cm2 (95% CI 0.79-0.93). Addition of PMA to the model with the clinical covariates resulted in an improvement in C-statistic from 0.57 to 0.67, and BIC from 307 to 301 (with lower BIC values preferred). PMA is independently associated with all-cause mortality after elective endovascular and open aortic aneurysm repair, and may be integrated into the pre-operative risk assessment to optimize care in high-risk frail patients.