Coronary artery dissection

Coronary artery dissection is a rare cause of acute coronary syndrome especially in young patients who are otherwise healthy.

A spontaneous coronary artery dissection (SCAD) is defined as a non-iatrogenic dissection of an epicardial coronary artery not associated with atherosclerosis or trauma.

Epidemiology

Coronary artery dissection occurs mainly in young, otherwise health patients especially in females in whom 84% of cases occur ¹. One study found the prevalence of coronary artery dissection in patients undergoing coronary angiography to be 0.1% with a mean age of 44 years ². In another study the the peak prevalence was at around 47 and 53 years ⁸. It is also thought to account for the highest prevalence (~15–20%) of peripartum myocardial infarctions ⁸.

Clinical features

The features of coronary artery dissection depends on the severity and extent of the dissection with presentations ranging from those of acute coronary syndrome to sudden death ³.

Pathology

Coronary artery dissection is believed to be due to an intramural hematoma in the wall of a coronary vessel creating a false lumen which then causes occlusion of the true lumen. The effect of this is reduced blood flow and consequently ischemia in the cardiac muscle ³.

Associations

Many cases are idiopathic although it has been associated with many conditions

• fibromuscular dysplasia: considered the most common coexisting condition and according to some report has been present in up to 86% of cases of spontaneous coronary artery dissection ⁷. 

• pregnancy or being postpartum (up to a one-third of all cases)

• other reported associations include

  • atherosclerosis

  • connective tissue disease (e.g. Ehlers-Danlos syndrome type IV, Marfan syndrome, pseudoxanthoma elasticum and Loeys-Dietz syndrome)

  • other conditions and toxins (e.g. SLE, cocaine abuse) ³.

Radiographic features

Most of the literature describes coronary artery dissection as being diagnosed on coronary angiogram ³. However, it has also been diagnosed on CT coronary angiography in the past, resolution of the dissection has also been assessed using CT coronary angiography ⁴. The role of other imaging modalities is primarily to exclude other causes other chest pain (e.g. aortic dissection, pulmonary embolism). If an underlying condition is suspected or diagnosed (e.g. Marfan syndrome) imaging may be needed to exclude other sites of aneurysm.

Angiography / CT angiography

Described CT features include

• abrupt luminal stenosis: reported around 60-65% ⁹

• intramural hematoma: ~ 50%

• tapered luminal stenosis: ~ 35%

• direct dissection ~ 15%

Additional reported findings include epicardial fat stranding (~ 40%), coronary tortuosity ~ 30%) and coronary bridging ~ 15%

Some authors have suggested 3 imaging patterns ⁸.

• type 1: multiple lumens with contrast staining and occlusion distally.

• type 2: diffuse smooth stenoses > 20 mm

• type 3: focal short segmental stenoses < 20 mm

Treatment and prognosis

The survival from coronary artery dissection in one study was quoted to be up to 82% in long term follow up ¹. Treatment may be performed by stenting and more rarely surgery, but medical management only has also successfully been described ^5,6.

History and etymology

Spontaneous coronary artery dissection was first reported at autopsy by H C Pretty in 1931 ⁷. 

See also

• myocardial infarction