Scientific statement on spontaneous coronary artery dissection: care must be taken not to miss the association of spontaneous coronary artery dissection and takotsubo syndrome

Spontaneous coronary artery dissection (SCAD) is defined as a non-traumatic, non-iatrogenic, and non-atherosclerotic acute spontaneous separation of the coronary arterial wall layers due to bleeding into the arterial wall resulting in a false lumen compressing the true lumen and compromising the coronary arterial flow. The invasive coronary angiography (CAG) is the most important diagnostic route to identify SCAD. According to the findings of CAG, SCAD is classified simply into angiographically visible SCAD [type1 according to Saw classification (1)] and angiographically invisible SCAD [type 2A, 2B and type 3 according to Saw classification (1)]. In the angiographically visible SCAD, the pathognomonic angiographic signs as double or multiple radiolucent lumens of different opacities, radiolucent intimal flap, or contrast staining of the vessel wall are seen during CAG (Figure 1A,B); in detecting these signs, the diagnosis of SCAD will be confirmed. In the angiographically invisible SCAD, the above-mentioned pathognomonic signs are not seen. In the invisible SCAD, there will be usually a long diffuse smooth narrowing of the coronary artery with an abrupt demarcation of the proximal normal part of the vessel and a normal segment after the end of the lesion (type 2A) (Figure 1C,D,E). The invisible SCAD may involve the peripheral segments of the coronary arteries and seen as “normal tapering” vessel (type 2B) (Figure 1F,G). The SCAD lesion in the invisible SCAD may also be short mimicking an atherosclerotic coronary lesion (type 3) (Figure 1H,I,J). With invasive CAG, the diagnosis of invisible SCAD will be only suspected and may be confirmed by invasive intra-coronary imaging as intravascular ultrasound (IVUS) imaging and optical coherence tomography (OCT) imaging (2-4) (Figure 1D,E), where an intimal tear and/or an intramural hematoma and double lumen (false and true) will confirm the SCAD diagnosis. When the SCAD lesion is distal and the intravascular imaging deemed to be associated with substantial risks, the diagnosis of the invisible SCAD may be confirmed with repeated CAG after 6–8 weeks where angiographic healing of the SCAD lesions is seen (Figure 1G,J). Computed cardiac tomography angiography (CCTA) may also be valuable for noninvasive follow up of patients with proximal SCAD. SCAD involving the distal or small coronary arteries is generally not visualized with CCTA