Spontaneous coronary artery dissection classification

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Spontaneous Coronary Artery Dissection Microchapters

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Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Spontaneous coronary artery dissection from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Approach

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

Angiography

CT

MRI

Echocardiography

Other Imaging Findings

Other Diagnostic Studies

Treatment

Treatment Approach

Medical Therapy

Percutaneous Coronary Intervention

Surgery

Primary Prevention

Secondary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

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 Example
Type 1
  • Pathognomonic multiple radiolucent lumen
  • Contrast dye staining of arterial wall
  • Presence or absence of dye hang-up or slow contrast clearing from the lumen
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2
Type 2
  • Diffuse (typically >20–30 mm)
  • Smooth narrowing varying in severity (ranging from 40 to 100% stenosis)
  • No response to intracoronary nitroglycerin
  • No atherosclerotic lesions in other coronary arteries
  • Repeat coronary angiogram showing spontaneous resolution of the dissected segment or previous angiogram showing normal artery
  • Intracoronary imaging with OCT or IVUS proving the presence of intramural hematoma and double-lumen
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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
  • Mimics atherosclerosis with focal or tubular stenosis
  • Lack of atherosclerotic changes in other coronary arteries
  • Long lesions (11–20 mm)
  • Hazy stenosis
  • Linear stenosis
  • Note: requires OCT or IVUS to prove the presence of intramural hematoma or double-lumen
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2

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.

References

  1. 1.0 1.1 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.
  2. 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.