Sixty-nine patients undergoing elective cardiac surgery participated in this study. The 24-h urinary 3-MH/Cr was collected for 3 days after surgery. Serum levels of metabolic markers, amino acids, and skeletal muscle strength were measured before and after surgery. Cumulative 3-MH/Cr during 3 days after surgery (cum3-MH/Cr) was 676.7 ± 169.0 nmol/g Cr, and was positively associated with the decrease in muscle strength. In multivariate analysis, factors associated with an increased cum3-MH/Cr were preoperative grip strength (β = −0.309, p = 0.003), body mass index (β = −0.299, p = 0.001), hemoglobin (β = −0.243, p = 0.007), cardiopulmonary bypass time (β = 0.184, p = 0.049), and immediate post-operative interleukin-6 (β = 0.295, p = 0.002).
Our findings suggest that post-operative muscle proteolysis is facilitated by preoperative catabolic accelerators in patients undergoing cardiac surgery. The factors of muscle proteolysis immediately after surgery may be a novel therapeutic target in rehabilitation intervention.