Off-pump Surgery Mitigates Risk in Patients Undergoing Coronary Artery Bypass Grafting with Evidence of Liver Dysfunction

Background: Liver dysfunction is a feared risk factor in cardiac surgery, which may not be appropriately reflected in our current risk assessment. The MELD score has been developed to assess the degree of liver dysfunction, guiding decision making in the treatment of portal hypertension or liver transplantation. In patients with liver cirrhosis, the use of cardiopulmonary bypass has been identified as a risk factor for mortality. We here assessed the influence of the MELD XI score on mortality in patients having undergone elective On-pump or Off-pump coronary bypass grafting (CABG).

Method: We calculated MELD XI (MELD-XI  =  5.11 × ln (serum bilirubin in mg/dL) + 11.76 × ln (serum creatinine in mg/dL) + 9.44) for 3535 consecutive patients having undergone elective CABG between December 2009 and May 2020. A MELD XI threshold value was determined using the Youden index based on receiver operating characteristics (ROC). An uni- and multivariable Cox proportional hazards analysis was performed to identify predictors of mortality.

Results: Patients were 68 ± 10 years old and 76% were male. Average MELD-XI was 9.3 ± 3.3. The MELD XI threshold was 11. Patients below this threshold had slightly lower EuroSCORE II (n = 2,630; 3.5 ± 4.0) than those above the cut off (n = 905, 4.1 ± 4.7, p < 0.01) which was mainly due to advanced age, lower ejection fraction, more diabetes mellitus, and more renal dysfunction (all p < 0.01). Off-pump CABG was used in 2,334 and on-pump in 1,201 patients. Mortality was higher in on-pump than in off-pump patients (3.8 vs. 2.2%; p < 0.03). Applying the MELD XI threshold revealed that mortality below MELD XI of 11 was not different between on- and off-pump (2.2 vs. 1.2%, p = 0.34). However, above MELD XI of 11 mortality was significantly higher in the on-pump group (8.9 vs. 4.9%, p < 0.02). This risk mitigating effect of off-pump CABG was a function of MELD XI (Figure).

Conclusion: Patients with evidence of liver dysfunction, as assessed by the MELD XI score, are at increased risk for perioperative mortality. This risk can significantly be mitigated by performing CABG Off-pump.

Publication History

Article published online:
03 February 2022