Forgot your password?
Management of SCAD
Dr Tharusha Gunawardena
Introduction:
Spontaneous coronary artery dissection (SCAD) refers to blood entering and separating the layers of the coronary arterial wall to form a false lumen. This leads to external compression of the true coronary lumen, restricting coronary blood flow and leading to coronary insufficiency. Whilst SCAD is considered a “generally” uncommon cause of acute coronary syndrome (0.1-0.4% of all ACS cases), it contributes to a third of ACS presentations in women <50 (it is the commonest cause of ACS during pregnancy). It is therefore important to consider and recognise SCAD in patients presenting with acute chest pain. The Mayo Clinic registry of 87 consecutive patients with SCAD reported a mean age of 43 years; 82% were female. No cause was identified in 45% of all cases, highlighting that many cases of SCAD remain unexplained.
SCAD should be distinguished from atherosclerotic dissections arising from plaque rupture events or erosions allowing blood to enter the intimal space and from iatrogenic dissections arising during coronary procedures. Certain SCAD subtypes can be challenging to distinguish angiographically, so further delineation with intracoronary imaging is advisable.
Predisposing factors:
The patients usually do not have traditional atherosclerotic risk factors, though there is a comparable prevalence of hypertension and hypercholesterolemia in the SCAD cohort compared to the atherosclerotic ACS population. A Canadian cohort study suggested that migraines (33%), anxiety (20%), and depression (20%) were relevant comorbid associations.
Clinical presentation:
Whilst patients may present with typical ACS symptoms of chest discomfort, diaphoresis and nausea, symptoms may seem to have a more abrupt onset. SCAD has also been known to present with acute heart failure, arrhythmia or cardiac arrest. Up to 50% may present with STEMI. Lobo et al (2019) identified 53 SCAD patients among a cohort of 5208 STEMI patients. Those SCAD patients were found to have been more likely (than those with atherosclerotic disease) to develop cardiogenic shock or have left main stem (LMS) or left anterior descending (LAD) disease.
Pregnancy and SCAD:
Pregnant patients with cardiac conditions are managed with a greater degree of anxiety and wider concern. Patients with pregnancy-associated SCAD unfortunately tend to have a more severe clinical course. Most cases occur in the first four weeks post-partum, but can occur at any time during the pregnancy or post-partum.
Angiography should NOT be avoided solely based on concerns regarding fetal radiation, given the clear benefit to the mother of early angiography to confirm the diagnosis and the relative low level of fetal radiation with the appropriate precautions (Hayes et al, JACC 2020).
Management is largely as for non-pregnant patients, but patients should be managed in a multidisciplinary capacity including obstetricians. There will be special considerations for longer term medications, including choice of betablockers and avoidance of ACE-inhibitors.
Despite limited data on outcomes, if a patient has had SCAD then they are generally advised against pregnancy even if the initial SCAD was not pregnancy related (ESC 2018). The sequelae of a previous SCAD, including LV function, will affect individual risk. The theoretical risk of recurrence would necessitate management as a high-risk pregnancy, with close collaboration between obstetricians and cardiologists.
A Mayo Clinic registry study (Gulati 2015) looked at 31 pregnancies in 22 SCAD women resulting in 19 live births, with two patients experiencing recurrence of SCAD but the majority having uncomplicated pregnancies.
Diagnosis:
SCAD is underdiagnosed and this is in part likely due to the heterogeneity of appearances in presentation. The classic description is of a longitudinal filling defect, representing the radiolucent intimal flap. There is often contrast staining of the arterial wall with appearance of a double lumen. There are various different classifications encompassing the different appearances, a commonly used one as below:
Figure 1: the four commonly used subtypes in the angiographic classification of SCAD.
Source: Djokovic A, Krljanac G, Matic P, Zivic R, Djulejic V, Marjanovic Haljilji M, Popovic D, Filipovic B, Apostolovic S. Pathophysiology of spontaneous coronary artery dissection: hematoma, not thrombus. Front Cardiovasc Med. 2023 Oct 20;10:1260478. doi: 10.3389/fcvm.2023.1260478. PMID: 37928766; PMCID: PMC10623160.
In CanSCAD, the most common angiographic appearance was Type 2 (60.2% of presentations)
Figure 2: Intracoronary imaging of SCAD:
Spontaneous coronary artery dissection (SCAD) hallmarks in intracoronary imaging. FL, false lumen; IMH, intramural haematoma; TL, true lumen. Arrow indicates myoendothelial lamina (intimo-medial flap).
SOURCE: Macaya, Fernando & Salinas, Pablo & Gonzalo, Nieves & Fernández-Ortiz, Antonio & Macaya, Carlos & Escaned, Javier. (2018). Spontaneous coronary artery dissection: Contemporary aspects of diagnosis and patient management. Open Heart. 5. e000884. 10.1136/openhrt-2018-000884.
Management:
The Initial treatment given to standard ACS patients are applicable to SCAD, with the initial use of dual antiplatelet agents, heparin and beta-blockers to preserve patency of the true lumen and prevent thrombotic occlusion.
As most dissected segments will heal spontaneously, conservative management is advisable in stable patients with SCAD. PCI is the preferred revascularisation strategy, but is associated with significant challenges and has reported success rates of <50%. Therefore recommendations to intervene are limited to certain scenarios:
GPIIb/IIIa inhibitors have also been used without complications. However, these agents could potentially delay healing of the intramural haematoma and lead to dissection extension. Thrombolytic agents should not be used due to an increased risk of bleeding and extension of intramural haematoma.
PCI in SCAD
As should be common practice, conscientious consideration of careful catheter manipulation, coaxial positioning and contrast injections are especially important in SCAD, as the risk of iatrogenic dissection is greater. Coronary angiography provides poor visualisation of intramural haematoma, and intravascular imaging with OCT or IVUS is recommended in all PCI cases. Whilst OCT may be used with caution, given the necessity for a strong contrast clearing injection, it could be considered superior given its great resolution than IVUS. It gives more detail to confirm guidewire position in the true lumen, detail the site of intramural haematoma and intimal tear, facilitate appropriate vessel sizing and optimise stent expansion.
Technical difficulties include careful negotiation of the guidewire to ensure it is truly luminal, to avoid dissection or haematoma extension and side branch occlusion.
Stent placement can result in haematoma propagation and loss of vessel flow. The data suggests that SCAD cases disproportionately require multiple additions of long lengths of stents. There is also a greater long-term risk of stent malappposition following reabsorption of the intramural haematoma and therefore conferring a longer term risk of late stent complications.
CABG is considered for patients with left main stem dissections or when PCI has been unsuccessful or is not technically feasible. The rate of emergency CABG for PCI failure is significant, varying between 10% and 13% in a reported series suggesting that perhaps PCI for SCAD would be safer in surgical centres.
Cutting balloons in SCAD:
Given the additional difficulties of stent implantation including intramural haematoma propagation and side branch compromise, there are case reports of patients being treated with cutting or scoring balloons to “release” the haematoma.
Figure 3: A case report detailing pre and post cutting balloon treatment of SCAD
Source: Zghouzi M, Moussa Pacha H, Sattar Y, Alraies MC. Successful Treatment of Spontaneous Coronary Artery Dissection With Cutting Balloon Angioplasty. Cureus. 2021
Other case reports of the use of cutting/scoring balloons in SCAD:
| Author | Year | Age | Sex | Location | Treatment | Imaging follow-up |
| Terzian et al. [10] | 2019 | 34 | F | LAD | Scoring balloon angioplasty | Coronary angiogram at 9 months |
| Kaya et al. [11] | 2019 | 46 | F | LAD | Cutting balloon angioplasty | Coronary CTA at 1 and 6 months |
| Sharma et al. [12] | 2019 | 53 | F | RCA | Cutting balloon angioplasty | NA |
| Main et al. [13] | 2019 | 62 | F | Large diagonal branch | Cutting balloon angioplasty | ECG in 6 weeks |
| Bresson et al. [14] | 2019 | 36 | F | Proximal LAD | Stenting and cutting balloon angioplasty | NA |
| McGrath et al. [15] | 2018 | 51 | F | LM, LAD, LCX | Stenting and cutting balloon angioplasty | NA |
| Noguchi et al. [16] | 2018 | 42 | M | LAD, LCX | Cutting balloon angioplasty and stenting | Coronary angiogram at 6 months |
| Ito et al. [17] | 2017 | 46 | F | LAD | Cutting balloon angioplasty | Coronary CTA at 3 months |
| Alkhouli et al. [18] | 2016 | 50 | F | LAD | Cutting balloon angioplasty and stenting | NA |
| Yumoto et al. [19] | 2014 | 47 | F | LAD | Cutting balloon angioplasty | Coronary angiogram at 6 months |
| Uema et al. [20] | 2013 | 42 | F | LAD | Cutting balloon angioplasty | NA |
Post SCAD screening:
A third to half of SCAD patients will also be diagnosed with Fibro Muscular Dysplasia; therefore SCAD patients should have CT/MR angiography for extra-coronary vascular abnormalities. Some studies have reported FMD in 11-86% of SCAD patients.
Outlook/prognosis of SCAD:
Two single-centre registries have provided important data on the natural history and prognosis of SCAD.
Saw et al. 2014 reported the results of a single-centre Canadian registry of 164 patients with SCAD.
Tweet et al. 2012 reported the results for 189 patients with first presentation of a SCAD episode. Women made up 92% of them, with a mean age of 44 years.
These findings are in keeping with previous reports suggesting that patients should receive careful in-hospital monitoring for up to one week due to the risk of further, recurrent events. This contrasts with atherosclerotic ACS cases where guidelines emphasise an early intervention and discharge approach.
In patients with recurrent SCAD, 75%-90% of those events involved coronary segments not affected at the time of the initial presentation. This would suggest that the risk for SCAD involves the entire epicardial coronary artery circulation and is not limited to isolated segments.
Take home messages:
References: