On the provenance of spontaneous coronary artery dissection.

Spontaneous coronary artery dissection is an unusual, but increasingly recognized, cause of acute coronary syndrome. It is a potentially fatal disorder that predominantly (>90% of cases) affects women, who are about 20 years younger (age 45-52 years) than those presenting with an acute coronary syndrome due to atherosclerotic coronary artery disease, and is the commonest cause of myocardial infarction associated with pregnancy. With the advent of improved coronary artery imaging modalities, including invasive coronary angiography, intravascular ultrasonography (IVUS), and optical coherence tomography (OCT), spontaneous coronary artery dissection is being increasingly diagnosed. It is typically due to a spontaneous bleed in the tunica media of an epicardial coronary artery, with or without an intimal tear, that results in an intramural haematoma; the latter, in turn causing a separation or dissection of the lamellae formed by the layers of smooth muscle cells of the tunica media, which can propagate longitudinally. Although coronary artery dissection can be due to atherosclerotic disease that may, in fact, present spontaneously, or to trauma, or guidewire-induced intimal injury, the understanding that the entity now known as