Definitions

• MINOCA = Myocardial Infarction with No Obstructive Coronary Atherosclerosis
• A clinical syndrome defined by:
  • Evidence of MI
  • Normal or near normal coronary arteries on angiography (stenosis <= 50%)

Epidemiology

• MINOCA is the cause of AMI in about 6% of cases

Prognosis

• Uncertain due to the varied underlying conditions
• Generally has a lower in-hospital and 12-month mortality than MI due to obstructive CAD

Causes of MINOCA

Epicardial Vessels

• Coronary artery vasospasm / variant angina / Prinzmetal angina
  • Can be localized univessel, or multifocal, or even multivessel
  • Autonomic triggers
  • Drugs: ephedrine, cocaine, MJ, ETOH, butane, sumatriptan, amphetamines
  • PCI guide wire or balloon dilatation
  • Botulism
  • Mg deficiency
  • Allergy (Kounis syndrome)
• Non-obstructive eccentric plaque, with acute thrombosis
  • May by missed on angiography due to eccentric growth and a thin cap
  • Needs intravascular imaging: ICT, intravascular ultrasound

Coronary Microvasculature

• Takotsubo CM
  • Apical ballooning of the LV in the absence of CAD
• Coronary microvascular dysfunction ("coronary syndrome X" or "angina pectoris with normal coronary arteries)
  • Transient myocardial ischemia with ST changes and angina;
  • Spontaneous or induced by intracoronary ACh;
  • Absence of obstructive CAD and epicardial spasm
• Viral myocarditis
  • Adenovirus, parvovirus B19, HHV6, Coxsackievirus
  • HIV
• Coronary artery embolism
  • Often affects the microvasculature, but may be also associated with visible embolization of the epicardial coronary artery branches on angiography
  • Suspect with MINOCA and once of:
    • Prosthetic valve
    • AF
    • DCM with apical thrombus
    • Rheumatic heart disease with MS
    • IE
    • Atrial myoxoma
    • Paradoxical embolism

Management

• MINOCA has a similar risk of recurrent CV events over time, comparable to ACS and obstructive atherosclerosis
• Requires DAPT 12/12 + statins

Resources

• AHA Review 2017 https://www.ahajournals.org/doi/full/10.1161/circulationaha.117.027666
• AHA Review 2019 https://www.ahajournals.org/doi/10.1161/CIR.0000000000000670
• https://www.uptodate.com/contents/myocardial-infarction-with-no-obstructive-coronary-atherosclerosis?search=minoca&source=search_result&selectedTitle=1~2&usage_type=default&display_rank=1