Definition

• The original definition (2014) was myocardial injury due to myocardial ischemia, during or within 30 days after non-cardiac surgery
• Currently, MINS is defined as
  • (1) elevated post-operative troponin, due to myocardial ischemia
    • Normal troponin T > 30 ng/L;
    • hsTnT between 20 to 65 with absolute rise of at least 5;
    • hsTnT >65
  • (2) during or within 30 days of non-cardiac surgery
  • (3) not requiring ischemic features (symptoms, ischemic EKG findings)
• MINS includes
  • MI (both symptomatic and non-symptomatic); and
  • patients with postoperative elevations in troponin but who do not have symptoms, electrocardiographic abnormalities, or other criteria that meet the universal definition described above, and have no evidence of a nonischemic etiology for their troponin elevation

Pathophysiology

• MINS excludes a non-ischemic etiology:
  • AFRVR
  • Sepsis
  • Pulmonary embolism
• The majority (>85%) of postoperative hsTn elevations are due to myocardial ischemia
• Ischemia is, at its core, due to coronary artery supply-demand mismatch and/or thrombosis
• Etiology:
  • Thrombosis (1/4 to 1/3) is relatively uncommon cause of MINS
  • Supply-demand mismatch (Almost all patients have underlying coronary artery stenosis)

Significance

• MINS is independently associated with 30 day and 1-year mortality
• Increases the risk for:
  • Recurrent MI
  • CHF
  • Serious arrhythmia

Management of MINS

Medical Management

• ASA and statin should be started; i.e. cardiovascular medication intensification for CAD
• Beta blocker if hypertensive and tachycardic
• ACE inhibitor if hypertensive with no tachycardia
• The above are based on risk-adjusted observational data
• Dabigatran
  • Evidence: MANAGE RCT (Lancet, PJ Devereux)
  • However, dabigatran was compared to placebo control and grouped arterial and venous thrombosis.

Coronary Revascularization

• Data shows there may be benefit; risks are high:
  • Bleeding
  • Low rate of revascularization with coronary angiography (37%)
• Wise to only go for cath with MINS if there is recurrent cardiac instability (heart failure, ischemia)

Troponins after surgery

• Most MINS/MI happens within 48 hours after surgery, and often is asymptomatic
• Asymptomatic cases have the same risks as symptomatic cases
• The vast majority (82-93%) of MINS occurs without any ischemic symptoms, and need troponin screening
• Recommendations:
  • Screen patients who are at high risk for cardiac injury:
    • Over 65 years of age
    • History of atherosclerotic disease
  • Measure troponins on days 1, 2, 3, after non-cardiac surgery while in hospital

References

EHJ MINS https://academic.oup.com/eurheartj/article-abstract/41/32/3083/5490290 (PJ Devereux)