Psoas Muscle Area and Length of Stay in Older Adults Undergoing Cardiac Operations.

Background: Frailty assessment can help predict which older adults will experience adverse events after cardiac surgical procedures. Low muscle mass is a core component of frailty that is suboptimally captured by self-reported weight loss; refined measures using computed tomographic (CT) images have emerged and are predictive of outcomes in noncardiac surgical procedures. The objective of this study was to evaluate the association between CT muscle area and length of stay (LOS) after cardiac surgical procedures.

Methods: Frail patients who had a perioperative abdominal or thoracic CT scan were identified. The CT scans were analyzed to measure cross-sectional lean muscle area at the L4 vertebra (psoas muscle area [PMA], lumbar muscle area [LMA]) and the T4 vertebra (thoracic muscle area [TMA]). The associations of PMA, LMA, and TMA with frailty markers and postoperative LOS were investigated.

Results: Eighty-two patients were included; the mean age was 69.2 ± 9.97 years. Low muscle area was correlated with lower handgrip strength and short physical performance battery (SPPB) scores indicative of physical frailty. Postoperative LOS was correlated with PMA (R = -0.47, p = 0.004), LMA (R = -0.41, p = 0.01), and TMA (R = -0.29, p = 0.03). After adjustment for the predicted risk of prolonged LOS, age, sex, and body surface area, PMA remained significantly associated with LOS (β = -2.35, 95% CI -4.48 to -0.22). The combination of low PMA and handgrip strength, indicative of sarcopenia, yielded the greatest incremental value in predicting LOS.

Conclusions: Low PMA is a marker of physical frailty associated with increased LOS in older adults undergoing cardiac surgical procedures. Further research is necessary to validate PMA as a prognostic marker and therapeutic target in this vulnerable population.