Duration of Elevated Liver Enzymes After CABG Surgery
Elevated liver enzymes after CABG surgery typically show a significant increase within the first 72 hours post-surgery and generally return to normal levels within 7-10 days in most patients. 1
Patterns of Liver Enzyme Elevation After CABG
- Approximately 2% of patients show elevated liver enzymes (alanine and aspartate transaminases) in the weeks to months after surgery 2
- Significant increases in total bilirubin, aspartate aminotransferase (AST), and alkaline phosphatase are commonly observed by the third postoperative day 1
- AST and ALT typically peak at 72 hours post-CABG, with values reaching 99.3±19.5 U/L for ALT and 103.5±21.6 U/L for AST 1
- Most post-CABG liver enzyme elevations are transient and not associated with permanent hepatotoxicity or increased risk of hepatitis 2
Mechanisms of Liver Enzyme Elevation
- Global or regional ischemia related to inadequate intra-operative cardiac protection can affect liver perfusion and function 2
- Microvascular events related to reperfusion and oxygen free radical generation during CABG can cause hepatocellular damage 2
- Transient alterations of hepatic enzymes after CABG are presumably attributed to decreased hepatic flow, hypoxia, or pump-induced inflammation 1
- On-pump CABG procedures show higher cardiac biomarker release compared to off-pump CABG, which may correlate with liver enzyme elevation 2
Risk Factors for Prolonged Elevation
- Hypotension during surgery has a significant relationship with alkaline phosphatase and AST changes 1
- Longer pump time correlates with greater bilirubin changes between pre- and post-operative periods 1
- Pre-existing liver dysfunction significantly increases the risk of complications after CABG, including prolonged hospital stays 3
Timeline for Normalization
- Most patients show a slow return to normal liver enzyme values within 7-10 days after the procedure 1
- No data suggest that these transient elevations are associated with permanent liver damage 2
- In patients without pre-existing liver disease, the elevation pattern is similar to that seen in other surgical procedures with general anesthesia, such as laparoscopic cholecystectomy 4
Clinical Implications
- Monitoring of liver function is important, especially in patients who will be started on statins post-CABG, as active or chronic liver disease is a contraindication to statin use 2
- Resume statin therapy when the patient is able to take oral medications, unless contraindicated by liver enzyme elevations suggesting hepatotoxicity 2
- Adequate blood glucose control with continuous intravenous insulin to maintain postoperative blood glucose concentration ≤180 mg/dL is important, as hyperglycemia can worsen outcomes and potentially affect liver function 2, 5
Special Considerations
- Patients with pre-existing liver dysfunction have significantly worse outcomes after CABG, including higher mortality (OR = 5.19; 95%CI = 2.93-9.20) and increased rates of complications 3
- Some medications may have protective effects against liver enzyme elevation - for example, metformin has been associated with reduced post-operative surge in total bilirubin and transaminase liver enzymes in diabetic patients undergoing CABG 6