What is the initial management of a post-coronary artery bypass grafting (CABG) myocardial infarction (MI)?

Initial Management of Post-CABG Myocardial Infarction

Emergency revascularization is recommended for post-CABG MI patients with persistent ischemia of a significant area of myocardium and/or hemodynamic instability refractory to nonsurgical therapy. 1

Immediate Assessment and Management

Hemodynamic Stabilization

• Optimize determinants of coronary perfusion:
  • Heart rate control
  • Maintain adequate diastolic or mean arterial pressure
  • Optimize right ventricular or left ventricular end-diastolic pressure 1
• For cardiogenic shock: Consider mechanical circulatory support (intra-aortic balloon pump)
• Monitor with continuous ST-segment monitoring for ischemia detection 1

Pharmacological Management

• Begin metoprolol therapy as soon as hemodynamically stable:
  • Initial IV bolus: Three 5 mg injections at 2-minute intervals (monitor BP, HR, and ECG)
  • If tolerated, follow with oral metoprolol 50 mg every 6 hours for 48 hours
  • Maintenance: 100 mg orally twice daily 2
• Antiplatelet therapy:
  • Aspirin (standard of care)
  • Consider dual antiplatelet therapy (DAPT) - may reduce rehospitalization at 30 days 3

Decision Algorithm for Revascularization

Immediate Emergency CABG Indications (Class I):

1. Failed or impossible PCI with suitable coronary anatomy AND:

   • Persistent ischemia of significant myocardium at rest
   • Hemodynamic instability refractory to nonsurgical therapy 1

2. Mechanical complications of MI requiring surgical repair:

   • Ventricular septal rupture
   • Mitral valve insufficiency due to papillary muscle infarction/rupture
   • Free wall rupture 1

3. Cardiogenic shock with suitable anatomy for CABG (regardless of time from MI to shock onset) 1

4. Life-threatening ventricular arrhythmias with left main stenosis ≥50% and/or 3-vessel CAD 1

When NOT to Perform Emergency CABG (Class III: HARM):

• Patients with persistent angina but small area of viable myocardium who are hemodynamically stable
• Patients with no-reflow (successful epicardial reperfusion with unsuccessful microvascular reperfusion)
• After failed PCI without ischemia or threatened occlusion
• After failed PCI if revascularization is impossible due to target anatomy 1

Special Considerations

Timing of Surgery

• If immediate intervention is not required but revascularization is indicated, consider timing carefully:
  • CABG within 10 days after AMI is associated with significantly increased mortality, especially in elderly patients or those with severely impaired LVEF 4
  • When possible, defer surgery beyond 10 days post-MI to reduce mortality risk 4

High-Risk Patient Management

• For patients >70 years with ST-segment elevation or LBBB:
  • Early revascularization with PCI or CABG is reasonable regardless of time interval from MI to shock 1
• For patients with poor LV function:
  • CABG is recommended with significant left main stenosis, left main equivalent, or proximal LAD stenosis with 2- or 3-vessel disease 1
  • Placement of pulmonary artery catheter is indicated for patients in cardiogenic shock 1

Monitoring and Follow-up

• Intraoperative transesophageal echocardiography should be performed for evaluation of acute, persistent, and life-threatening hemodynamic disturbances 1
• Continuous ST-segment monitoring in the early postoperative period 1
• Consider cardiac rehabilitation for all eligible patients after stabilization 1

Caution

• Post-CABG MI patients have poorer short- and long-term outcomes compared to stable CAD patients after CABG, with risk differences continuing to increase with time 5
• MI-related death is the leading cause of death after PCI compared to CABG, particularly in patients with diabetes, 3-vessel disease, or high SYNTAX scores 6