Mechanisms of myocardial infarction without obstructive coronary artery disease.

Angiography in patients with myocardial infarction (MI) most commonly reveals one or more significantly narrowed coronary arteries, but a substantial minority of patients with spontaneous MI have no obstructive coronary artery disease (CAD) at angiography. This review summarizes evidence for the most commonly hypothesized mechanisms, including plaque disruption, plaque erosion, vasospasm, embolism, and spontaneous coronary dissection. In addition, tako-tsubo syndrome and myocarditis are discussed. The best treatment of MI without obstructive CAD is likely to differ substantially based on the underlying cause. Additional mechanistic research is needed to facilitate the design of research studies aimed at documenting the best treatments for these patients, numbering as many as 225,000 per year in the US.