Spontaneous coronary artery dissection classification
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Spontaneous Coronary Artery Dissection Microchapters |
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Differentiating Spontaneous coronary artery dissection from other Diseases |
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Diagnosis |
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Treatment |
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Case Studies |
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Type 1 Type 2A Type 2B Type 3 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Nate Michalak, B.A.
Synonyms and keywords: SCAD
Overview
Spontaneous coronary artery dissection can be classified based on angiographic appearance into type 1 (evident arterial wall stain with multiple radiolucent lumens), type 2 (diffuse smooth stenosis of varying severity), and type 3 lesions (focal or tubular stenosis mimicking atherosclerosis).
Classification
The National Heart, Lung, and Blood Institute (NHLBI) classification scheme for coronary dissection was devised in the pre-stent era for classifying the dissection following balloon angioplasty (i.e., iatrogenic dissection). In light of the distinctive angiographic features of spontaneous coronary artery dissection (SCAD), Saw et al. proposed a classification system to better characterize the lesions:[1][2]
| Type | Feature | |
|---|---|---|
| Type 1 |
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| Type 2 |
| |
| 2A variant | Normal arterial caliber proximal and distal to dissection | |
| 2B variant | Dissection extends to the distal tip of the artery without discernible normal segment distally | |
| Type 3 |
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Spontaneous Coronary Artery Dissection Type 1
Type 1 SCAD lesion is characterized by the pathognomonic appearance of contrast dye staining of arterial wall with multiple radiolucent lumens, with or without the presence of dye hang-up or slow contrast clearing from the lumen.
Projection angle: 14 RAO, 35 CRA. Type 1 SCAD is seen in OM2.
Spontaneous Coronary Artery Dissection Type 2
Type 2 SCAD lesion is characterized diffuse (typically >20–30 mm) and usually smooth narrowing that can vary in severity from an inconspicuous mild stenosis to complete occlusion, plus:
- a. no response to intracoronary nitroglycerin and no atherosclerotic lesions in other coronary arteries
- OR
- b. repeat coronary angiogram showing angiographic resolution of the dissected segment or previous angiogram showing normal artery
- OR
- c. intracoronary imaging with optical coherence tomography or intravascular ultrasound proving the presence of intramural hematoma (IMH) and double-lumen
Type 2 SCAD lesion commonly involves the mid to distal segments of coronary arteries, and can be so extensive that it affects the distal tip. Accordingly, type 2 lesions can be further divided into two variants (type 2 variant A and variant B).
Type 2 Variant A
In type 2 variant A lesion, the coronary segments proximal and distal to dissection are normal.
Projection angle: 25 LAO, 20 CRA. Type 2A SCAD is seen in R3, R4.
Type 2 Variant B
In type 2 variant B lesion, the dissection extends to the apical tip of the artery without discernible normal segment distally.
Projection angle: 41 RAO, 19 CRA. Type 2B SCAD is seen starting in L2 resulting in a total occlusion.
Spontaneous Coronary Artery Dissection Type 3
Type 3 SCAD lesion is characterized by focal or tubular (typically <20 mm) stenosis that mimics atherosclerosis, which requires intracoronary imaging (e.g. optical coherence tomography or intravascular ultrasound) to prove the presence of intramural hematoma or double-lumen. Angiographic features that may be useful in differentiating type 3 SCAD lesion from atherosclerosis include:
- a. lack of atherosclerotic changes in other coronary arteries
- b. long lesions (11–20 mm)
- c. hazy stenosis
- d. linear stenosis
Projection angle: 1 LAO, 35 CRA. Type 3 SCAD is seen in D1.
Algorithm for Diagnosing Non-Atherosclerotic Spontaneous Coronary Artery Dissection
A stepwise algorithm for diagnosing non-atherosclerotic SCAD has been proposed by Saw et al.[1] Clinicians should maintain a high index of suspicion for SCAD and consider early coronary angiography to ensure timely diagnosis and management. If the pathognomonic appearance of arterial wall stain with multiple radiolucent lumens is evident, then the diagnosis of type 1 SCAD can be established without additional intracoronary imaging. If type 1 SCAD appearance is not evident, angiographers should then assess for the presence of atherosclerotic changes in other coronary arteries, and consider intracoronary imaging if there is uncertainty as to non-atherosclerotic SCAD. For diffuse (>20 mm) and smooth stenosis of varying severity suggestive of type 2 SCAD, intracoronary nitroglycerin may be administered to rule out coronary spasm. If the stenosis remains unchanged after nitroglycerin administration, then optical coherence tomography (OCT) or intravascular ultrasound (IVUS) should be pursued. If there are concerns of compromising coronary flow with intracoronary imaging, then the stenosis could be reassessed in 4 to 6 weeks for hemodynamically stable patients, as SCAD typically resolves spontaneously.
Algorithm for the Angiographic Diagnosis and Confirmation of Spontaneous Coronary Artery Dissection[1]
Presence of features that raise suspicion for SCAD? ❑ Myocardial infarction in young women (age ≤50) ❑ Absence of traditional cardiovascular risk factors ❑ Little or no evidence of coronary atherosclerosis ❑ History of fibromuscular dysplasia ❑ History of connective tissue disorder or systemic inflammation ❑ Type 4 Ehlers-Danlos syndrome ❑ Systemic lupus erythematosus | |||||||||||||||||||||||||||||||
Perform early coronary angiography | |||||||||||||||||||||||||||||||
Presence of type 1 SCAD lesion characteristics? ❑ Contrast staining of arterial wall ❑ Multiple radiolucent lumens ❑ Contrast hang-up or slow clearing from the lumen | |||||||||||||||||||||||||||||||
YES | NO | ||||||||||||||||||||||||||||||
Type 1 SCAD most likely | Presence of type 2 SCAD lesion characteristics? ❑ Diffuse lesion (typically >20–30 mm) ❑ Smooth luminal narrowing with varying severity ❑ Involvement of mid to distal segments | ||||||||||||||||||||||||||||||
YES | NO | ||||||||||||||||||||||||||||||
Stenosis corrected by intracoronary nitroglycerin? | Look for type 3 SCAD lesion characteristics ❑ Focal or tubular stenosis (typically <20 mm) ❑ Mimics atherosclerosis ❑ Additional features ❑ No atherosclerosis in other arteries ❑ Long lesions (11–20 mm) ❑ Hazy stenosis ❑ Linear stenosis | ||||||||||||||||||||||||||||||
YES | NO | Type 3 SCAD most likely ❑ Consider OCT or IVUS for definitive diagnosis ❑ Reassess with angiography in 4 to 6 weeks | |||||||||||||||||||||||||||||
R/O coronary spasm or other conditions | Type 2 SCAD most likely ❑ Consider OCT or IVUS for definitive diagnosis ❑ Reassess with angiography in 4 to 6 weeks | ||||||||||||||||||||||||||||||
References
- ↑ 1.0 1.1 1.2 Saw J (2014). "Coronary angiogram classification of spontaneous coronary artery dissection". Catheter Cardiovasc Interv. 84 (7): 1115–22. doi:10.1002/ccd.25293. PMID 24227590.
- ↑ Saw J, Mancini GB, Humphries K, Fung A, Boone R, Starovoytov A; et al. (2016). "Angiographic appearance of spontaneous coronary artery dissection with intramural hematoma proven on intracoronary imaging". Catheter Cardiovasc Interv. 87 (2): E54–61. doi:10.1002/ccd.26022. PMID 26198289.