Preoperative Liver Stiffness is Associated With Hospital Length of Stay After Cardiac Surgery

Risk assessment models for cardiac surgery do not account for the degrees of liver dysfunction. Ultrasound shear-wave elastography measures liver stiffness (LSM), a quantitative measurement related to fibrosis, congestion, and inflammation. The authors hypothesized that preoperative liver stiffness would be associated with hospital length of stay after cardiac surgery.

Prospective observational study.

University hospital, single center.

One hundred five adult patients undergoing nonemergent cardiac surgery.

Preoperative liver stiffness measured by ultrasound elastography.

The associations were analyzed using linear mixed models, with adjustments for preoperative variables, duration of cardiopulmonary bypass, and type of surgery. Median liver stiffness was 6.4 kPa (range, 4.1-18.6 kPa). The median length of hospital stay was 6 days (range, 3-18 d). Each unit increase in liver stiffness, treated as a continuous variable, was associated with an increase of 0.32 ± 0.10 days in the hospital (p = 0.002). When treated as a categorical variable (<6 kPa, 6-9.4 kPa, and ≥9.5 kPa), LSM ≥9.5 kPa v LSM <6 kPa was associated strongly with an increase in hospital length of stay of 3.25 ± 0.87 days (p = 0.0003).

A preoperative LSM ≥9.5 kPa was associated with a significantly longer postoperative hospital length of stay. This association appeared independent of preoperative comorbidities commonly associated with coronary disease. Preoperative liver stiffness is a novel risk metric that is associated with the postoperative hospital length of stay after cardiac surgery.