Should we cancel the CABG procedure due to mild liver enzyme elevations in a patient on atorvastatin?

Management of Mild Liver Enzyme Elevations in a Patient on Atorvastatin Scheduled for CABG

The CABG procedure should proceed as scheduled despite mild liver enzyme elevations in a patient on atorvastatin. 1 Transient elevations in liver enzymes are expected in approximately 2% of patients on statins and are not associated with permanent hepatotoxicity or increased risk of hepatitis.

Rationale for Proceeding with CABG

• Statin therapy provides significant cardiovascular benefits for CABG patients:

  • Reduces rates of postoperative non-fatal MI and death
  • Decreases rates of postoperative atrial fibrillation (3.3% vs 23%)
  • Reduces neurological dysfunction, renal dysfunction, and infection 1, 2

• Mild liver enzyme elevations while on statins:

  • Are common (approximately 2% of patients) 1
  • Are typically transient and self-limiting 3
  • Do not indicate permanent hepatotoxicity 1
  • Should not lead to unnecessary discontinuation of these beneficial medications 4

Evidence Supporting Continuation of Statins

The 2011 ACCF/AHA guidelines for CABG specifically address this issue, stating that "no data are available to suggest that these elevations are associated with permanent hepatotoxicity or an increased risk of hepatitis" 1. The guidelines recommend discontinuing statins only in cases of active liver disease or development of myositis/rhabdomyolysis.

The GREACE study demonstrated that statin therapy is not only safe but potentially beneficial for patients with mild-to-moderate liver enzyme elevations. Patients with abnormal liver tests who received statins showed substantial improvement in liver function tests and a 68% relative risk reduction in cardiovascular events compared to those not receiving statins 5.

Perioperative Management Algorithm

1. Pre-operative assessment:

   • Confirm that liver enzyme elevations are mild (<3× ULN)
   • Rule out other causes of liver enzyme elevation (viral hepatitis, alcohol use)
   • Continue atorvastatin up to the day of surgery

2. Intraoperative management:

   • Proceed with CABG as planned
   • Use continuous intravenous insulin to maintain blood glucose ≤180 mg/dL 1

3. Post-operative management:

   • Resume atorvastatin as soon as the patient can take oral medications 1, 6
   • Monitor liver enzymes but do not discontinue statin unless:
     • ALT or AST ≥3× ULN with symptoms (fatigue, nausea, right upper quadrant pain)
     • ALT or AST ≥3× ULN with total bilirubin ≥2× ULN
     • ALT or AST ≥8× ULN 1

Important Considerations and Caveats

• Statin discontinuation risks: Patients in whom statins were discontinued after CABG have been shown to have higher mortality rates than those who continued statins postoperatively 1

• Monitoring: Continue to monitor liver enzymes postoperatively, but understand that transient elevations are common and typically resolve within 8 weeks even with continued statin therapy 1

• Dose adjustment: If concerned about statin-related liver effects, consider switching to pravastatin (which is less dependent on CYP3A metabolism) rather than discontinuing statin therapy altogether 7

• Drug interactions: Be aware that atorvastatin is a CYP3A substrate and may interact with other medications. Limit atorvastatin dosage to 40 mg/day when used with certain medications 1

By following this approach, you can ensure the patient receives the cardiovascular protective benefits of statin therapy while minimizing any potential risks associated with mild liver enzyme elevations.