Type 3 SCAD, the least common type, is also due to an intramural hematoma causing coronary stenosis, but the lesions are shorter than as seen in type 2 SCAD, being less than 20 mm in length. Due to the short segment of coronary stenosis in type 3 SCAD, it is often difficult to differentiate type 3 SCAD lesions from coronary stenosis due to atherosclerotic plaques and intra-coronary imaging is often needed to distinguish between the two. Some authors have proposed a fourth designation of SCAD, type 4 SCAD, in which there is a complete intraluminal occlusion of the coronary artery due to any of the  previously mentioned types (Type 1–3). Intracoronary imaging
Intracoronary imaging (ICI), consisting of intracoronary optical coherence tomography (OCT) and intravascular ultrasound (IVUS) can help distinguish SCAD from an atherosclerotic lesion when it is difficult to do so with angiography. ICI techniques provide a direct view of the walls of the coronary artery to confirm SCAD, but may actually worsen the dissection as the probes are inserted into the damaged area. ICI confers a 3.4% risk of iatrogenic dissection in people with SCAD compared to 0.2% risk in the general population. Between the two ICI methods, OCT - a newer technique - has superior spatial resolution than IVUS and is the preferred technique if ICI is required, but the need to inject extra contrast with OCT poses risk for worsening the dissection. Other methods
Some studies propose coronary CT angiography to evaluate SCAD in lower-risk people, with research into the approach ongoing.
Even afterwards, SCAD has a high recurrence risk at 30% within 10 years, often at a different site than the initial lesion - meaning that stents placed in the location of the first lesion may not protect against a second. Given the lack of consensus on the cause of SCAD, prevention of future SCAD may include medical therapy, counseling about becoming pregnant again (for those who had pregnancy-associated SCAD), or avoidance of oral contraceptives - as they contain estrogen and progesterone. Epidemiology
SCAD is the most common cause of heart attacks in pregnant and postpartum women. Over 90% of people who develop SCAD are women. It is especially common among women aged 43–52. With angiography and improved recognition of the condition, diagnosis of SCAD has improved since the early 2010s. While prior studies had reported a SCAD prevalence of less than 1% in patients presenting with acute coronary syndrome, more recent data suggests the prevalence of SCAD in acute coronary syndrome patients may be between 2-4%. History
SCAD was first described in the year 1931, at postmortem examination, in a 42-year-old woman. Due to a lack of recognition and diagnostic technology though, SCAD literature until the 21st century included only case reports and series. With the recent advent of coronary angiography and intracoronary imaging, recognition and diagnosis of SCAD has greatly increased, especially in the 2010s. See also
Dissection (medical)
Aortic dissection
Kounis syndrome

References
External links

"Spontaneous Coronary Artery Dissection Postpartum"
"Spontaneous-Coronary-Artery-Dissection-Case-Series-and-Review"