Frailty is an important predictor of outcomes after cardiac surgery, but utility is limited by difficult assessment and quantification. We hypothesize that sarcopenia defined as psoas muscle cross-sectional area is a useful predictor of surgical aortic valve replacement outcomes in moderate to high-risk patients.
Moderate to high risk patients (predicted risk of mortality greater than 3%) who underwent surgical aortic valve replacement with or without coronary artery bypass were extracted from an institutional database (2009 to 2016). Psoas index was calculated as the cross-sectional area of the psoas muscle at the L4 vertebral level normalized to body surface area. Patients were stratified by sarcopenia status, defined as less than 25th sex-specific percentile. Multivariable regression analysis identified risk-adjusted associations with psoas index using The Society of Thoracic Surgeons predicted risk scores.
Of the 240 patients included, the median predicted risk of mortality was 6%, median age 80 years, and 40% were female. Patients with (33.3%) and without (66.7%) sarcopenia had equivalent baseline risk (median predicted risk of mortality 5.7% versus 6.0%, p = 0.29). Patients with sarcopenia had higher 1-year mortality (31.9% versus 16.9% p = 0.03). Psoas index significantly predicted risk-adjusted 1-year mortality (odds ratio 0.84, p = 0.02) and long-term mortality (hazard ratio 0.92, p = 0.04), as well as risk-adjusted major morbidity, prolonged ventilation, length of stay, discharge to a facility, and hospital cost. Finally, psoas index measurements were highly reproducible (Pearson correlation coefficient 0.944).
Psoas index is an easily obtained and reproducible measure of frailty that predicts risk-adjusted resource utilization, morbidity, and long-term mortality. Psoas index may improve procedural selection and risk adjustment in high-risk patients with aortic valve disease.