Psoas muscle area and attenuation are highly predictive of complications and mortality after complex endovascular aortic repair.

OBJECTIVE

The present study evaluated the psoas muscle area and attenuation (radiodensity), quantified by computed tomography, together with clinical risk assessment, as predictors of outcomes after fenestrated and branched endovascular aortic repair (FBEVAR).

METHODS

The present single-center study included 504 patients who had undergone elective FBEVAR for pararenal or thoracoabdominal aortic aneurysms. The clinical risk assessment included age, sex, comorbidities, body mass index, glomerular filtration rate, aneurysm size and extent, cardiac stress test results, ejection fraction, and American Society of Anesthesiologists (ASA) score. Preoperative computed tomography was used to measure the psoas muscle area and attenuation at the L3 level. The lean psoas muscle area (LPMA; area in cm multiplied by attenuation in Hounsfield units [HU]) was calculated by multiplying the area by the attenuation. The risk factors for 90-day mortality, major adverse events (MAEs), and long-term mortality were determined using multivariable analysis. MAEs included 30-day or in-hospital death, acute kidney injury, myocardial infarction, respiratory failure, paraplegia, stroke, and bowel ischemia. A novel risk stratification method was proposed according to the strongest predictors of mortality and MAEs on multivariable analysis.

RESULTS

The 30-day mortality, 90-day mortality, and MAE rates were 2.0%, 5.6%, and 20%, respectively. The independent predictors of 90-day mortality were chronic obstructive pulmonary disease, chronic kidney disease, ASA score, and LPMA. The independent predictors of MAEs were aneurysm diameter, glomerular filtration rate, and LPMA. For long-term mortality, the independent predictors were chronic kidney disease, congestive heart failure, extent I-III thoracoabdominal aortic aneurysms, ASA score, and LPMA. The patients were stratified into three groups according to the ASA score and LPMA: low risk, ASA score II or LPMA >350 cmHU (n = 290); medium risk, ASA score III and LPMA ≤350 cmHU (n = 181); and high risk, ASA score IV and LPMA ≤350 cmHU (n = 33). The 90-day mortality and MAE rates were 1.7% and 16% in the low-, 7.2% and 24% in the medium-, and 30% and 33% in the high-risk patients, respectively (P < .001 and P = .02, respectively). Patients with ASA score IV and LPMA <200 cmHU, indicating sarcopenia (n = 14) had a 43% risk of death within 90 days. The 3-year survival estimates were 80% ± 3% for the low-, 70% ± 4% for the medium-, and 35% ± 9% for the high-risk patients (P < .001). The mean follow-up time was 3.1 ± 2.3 years.

CONCLUSIONS

LPMA was a strong predictor of outcomes and the only independent predictor of both mortality and MAEs after FBEVAR. A high muscle mass was protective against complications, regardless of the ASA score. Risk stratification based on the ASA score and LPMA can be used to identify patients at excessively high operative risk.