Myocardial infarction without evidence of obstruction in Coronary angiogram 

A substantial proportion of patients with myocardial infarction (MI) have no angiographically obstructive (≥50% diameter stenosis) coronary artery disease (CAD), including ≈7% to 32% of women and 6% to 12% of men. Plaque rupture and ulceration are common in women with myocardial infarction without angiographically demonstrable obstructive coronary artery disease. Vasospasm and embolism are possible mechanisms without plaque disruption. Intravascular ultrasound and cardiac magnetic resonance imaging provide complementary mechanistic insights into female myocardial infarction patients without obstructive coronary artery disease and may be useful in identifying potential causes and therapies.
http://circ.ahajournals.org/content/124/13/1414.abstract