Clinical Pearls & Morning Reports
Published December 9, 2020
Spontaneous coronary-artery dissection (SCAD) is defined as a separation of the layers of an epicardial coronary-artery wall by intramural hemorrhage, with or without an intimal tear. This condition is not associated with atherosclerosis, iatrogenic injury, or trauma. Read the NEJM Review Article here.
A: SCAD can affect both sexes across the life span, beginning in adolescence. However, approximately 90% of patients with this condition are women who present between 47 and 53 years of age. Cohort studies incorporating direct angiographic review indicate that one quarter to one third of myocardial infarctions in women younger than 50 years of age are caused by SCAD, and SCAD accounts for approximately 15 to 20% of myocardial infarctions during pregnancy or the peripartum period.
A: A consistent finding in registries of patients with SCAD is the high prevalence of concomitant noncoronary arterial abnormalities. In the cohorts with the highest incidence of screening, more than 50% of the patients also had fibromuscular dysplasia. Vascular abnormalities known to be associated with fibromuscular dysplasia have also been reported in multiple cohorts of patients with SCAD, even in the absence of diagnosed concurrent fibromuscular dysplasia. Whether or not SCAD is a coronary manifestation of fibromuscular dysplasia or a unique but related entity with a considerable number of arterial features in common, it is clear that SCAD may be a forme fruste of an underlying systemic arteriopathy that leaves the affected patient vulnerable to dissection when exposed to arterial shear stress related to an inciting trigger.
A: Patients in whom SCAD is the suspected cause of acute myocardial infarction should undergo coronary angiography to confirm the diagnosis. Coronary computed tomographic angiography (CCTA) is an attractive form of noninvasive ancillary imaging when the diagnosis of SCAD is uncertain on catheter-based angiography. However, there are limitations to CCTA in the diagnosis of SCAD and catheter-based coronary angiography remains the standard when SCAD is suspected. When angiography is not diagnostic for SCAD, ancillary imaging techniques such as intravascular ultrasonography or optical coherence tomography may be used for confirmation. Although intravascular imaging with intravascular ultrasound or optical coherence tomography can be a powerful diagnostic tool, procedural complications have been reported in up to 8% of patients with SCAD. Thus, intracoronary imaging is not without risk and is reserved for situations in which angiography is not diagnostic for SCAD or when intracoronary imaging is used for guidance during percutaneous coronary intervention (PCI).
A: The majority of medically treated SCAD lesions show angiographic evidence of healing over time, with restoration of blood flow and a decrease in the severity of stenosis. More than 80% of patients can be successfully treated medically, and expert consensus (not randomized trial data) suggests that medical management is preferred over immediate revascularization for patients who are in clinically stable condition. PCI for SCAD is challenging and is associated with worse short- and long-term outcomes than those associated with PCI for atherosclerotic lesions. Because the prevalence of coexisting arterial abnormalities outside the heart among patients with SCAD is high, axial imaging from the head to pelvis with dedicated computed tomographic angiography or magnetic resonance angiography is recommended. Mortality after SCAD is low. In contrast, the incidence of recurrent myocardial infarction is substantial, with 17 to 18% of patients having recurrent myocardial infarction over a span of 3 to 4 years. The majority of these recurrent myocardial infarctions are due to recurrent SCAD.