What are the guidelines for managing Myocardial Injury after Non-cardiac Surgery (MINS)?

Guidelines for Managing Myocardial Injury After Non-cardiac Surgery (MINS)

Routine postoperative troponin screening is recommended for high-risk patients undergoing non-cardiac surgery, with outpatient follow-up for cardiovascular risk factor optimization in those who develop MINS. 1

Definition and Significance

MINS is defined as:

• Elevated cardiac troponin (cTn) levels >99th percentile of the upper reference limit
• Occurring within 30 days after non-cardiac surgery
• Presumed ischemic origin (excluding non-ischemic etiologies like pulmonary embolism, sepsis, stroke)
• With or without ischemic symptoms or ECG changes 1, 2

MINS occurs in approximately 20% of patients undergoing non-cardiac surgery and is associated with:

• High 30-day mortality (~10%)
• Mortality risk proportional to peak troponin concentration
• 34% population attributable risk of 30-day postoperative mortality 1

Surveillance Recommendations

Who to Screen:

• High-Risk Patients: Recommended for troponin surveillance 1

  • Those with cardiovascular risk factors
  • Pre-existing cardiovascular disease
  • Kidney disease
  • Undergoing urgent/emergent surgery

• Low-Risk Patients: Routine screening NOT recommended (Class 2b, Level of Evidence: B-NR) 1

When to Screen:

• Obtain baseline preoperative troponin when possible
• Serial measurements during first 48-72 hours post-surgery
• Patients ≥65 years or with known atherosclerotic disease should have troponin measurements on days 1,2, and 3 after surgery 3

How to Screen:

• Either conventional fourth-generation or high-sensitivity troponin assays may be used 1
• ECG should be obtained if troponin is elevated or if symptoms develop 1

Management Algorithm for MINS

Immediate Assessment:

1. Rule out non-ischemic causes of troponin elevation:

   • Pulmonary embolism
   • Sepsis
   • Acute heart failure
   • Acute stroke 1

2. Determine if clinical features of MI are present:

   • Ischemic symptoms
   • ECG changes
   • Imaging evidence of new loss of viable myocardium 1

Management Recommendations:

For All MINS Patients:

• Cardiovascular Risk Factor Optimization (Class 2a, Level of Evidence: B-NR) 1

  • Outpatient follow-up with cardiology is reasonable
  • Early cardiology consultation has been associated with reduced mortality 1

• Consider Antithrombotic Therapy (Class 2b, Level of Evidence: C-LD) 1

  • May reduce thromboembolic events
  • Consider dabigatran 110 mg twice daily with low-dose aspirin if not at high bleeding risk 3

• Consider Statin Therapy

  • Associated with lower mortality at 1 year in observational studies 1, 3

• Avoid/Correct Precipitating Factors:

  • Hypotension
  • Tachycardia
  • Anemia (maintain hemoglobin ≥8 g/dL unless symptomatic) 1, 4

For MINS with Clinical Features of MI:

• Follow standard MI management protocols
• Consider cardiac catheterization for patients with recurrent instability (cardiac ischemia, heart failure) 3

Common Pitfalls and Caveats

1. Missing MINS diagnosis:

   • 80-90% of MINS cases occur without ischemic symptoms 1
   • Most MINS occurs within first 3 days after surgery 5

2. Misinterpreting troponin elevation:

   • Baseline elevation may be present in up to 21% of high-risk patients 1
   • Serial measurements help distinguish acute from chronic elevation 1

3. Lack of standardized management:

   • Optimal management strategy remains uncertain and requires further study 1
   • Less than one-third of MINS patients receive intensification of guideline-directed medical therapy 1

4. Overuse of invasive strategies:

   • Most MINS patients should only undergo cardiac catheterization if they demonstrate recurrent instability 3

5. Failure to provide follow-up:

   • MINS patients require outpatient follow-up for cardiovascular risk optimization 1
   • MINS identifies patients at increased risk for short and long-term mortality 2

By following these guidelines, clinicians can effectively identify and manage MINS, potentially reducing associated morbidity and mortality in the perioperative period.