Myocardial infarction without obstructive coronary artery disease

Purpose of review A substantial minority of myocardial infarction (MI) patients have no obstructive coronary artery disease (CAD) at angiography. Women more commonly have this type of MI, but both sexes are affected. This is not an innocuous problem. Multiple studies have shown 2% death or reinfarction in short-term to mid-term follow-up. Recent findings Two large autopsy series confirmed MI without obstructive CAD as a cause of death. Intravascular ultrasound (IVUS) and cardiac MRI (CMR) were studied in patients with MI without obstructive CAD. Plaque rupture was found in nearly 40% and late gadolinium enhancement was seen in nearly 40%, with little overlap in imaging findings. Additional CMR studies in similar patients have shown variable frequencies and patterns of late enhancement, but consistently demonstrate an ability to identify nonischemic causes (myocarditis, infiltrative disease). Ischemic myocardial injury on CMR may be due to plaque rupture but also occurs in patients without plaque rupture. These cases may be caused by vasospasm, embolism, dissection, or branch occlusion. Summary MI without obstructive CAD is a heterogeneous disorder with different mechanisms in different patients. Plaque rupture is common. In the absence of clear demonstration of a nonischemic cause, treatment should include guideline-recommended secondary prevention, including antiplatelet and antiatherosclerotic medications.