A 72-year-old man with history of treated hypertension, presented with sudden onset of chest pain at rest and evidence of minimal ST-segment elevation in the inferior electrocardiogram (ECG) leads. Urgent coronary angiography (CAG) demonstrated the diffuse mild stenosis from distal right coronary artery (RCA) to posterolateral (PL) branch (Fig. A). The non flow-limiting nature of the lesion and the suspicious RCA, potentially culprit lesion, led to assessment with optical coherence tomography (OCT). OCT (Video 1) demonstrated false lumen with intramural hematoma between distal RCA and PL branch and folding of the luminal intimal contour at distal RCA (Fig. B1 and C1). The patient was diagnosed as spontaneous coronary artery dissection (SCAD) type 3 and hemodynamically stable and asymptomatic. Therefore further intervention was avoided at this time and patient was discharged on dual antiplatelet therapy with aspirin and clopidogrel for 6 months. 6-month follow-up CAG showed improved luminal caliber in the affected segments and preserved good distal flow (Fig D). Follow-up OCT (Video 2) demonstrated healed intramural hematoma with enlarged caliber in distal RCA (Fig. B2) and complete resolution of intramural hematoma in PL branch (Fig. C2).
SCAD is a spontaneous separation of the coronary wall associated with intramural hematoma1. Even though SCAD was reported a rare disease in the studies based on coronary angiographic finding, OCT demonstrated that the prevalence of SCAD was not rare in a recent study2. Moreover, one third of SCAD cases can be only identified by coronary angiography and about two third of SCAD patients should be needed intra-coronary imaging, particularly the high resolution (10 µm) provided by OCT, to confirm intima tear, intramural hematoma, and false lumen3. Even though suboptimal blood clearance was potential limitations with OCT in the setting of SCAD, we reported equivalent medial area in lesion and normal segment supported the diagnosis of intramural compression, particularly when observed in associated with luminal folding, which was difficult to evaluate by IVUS4. Especially SCAD type 3, mimic atherosclerosis, is the most challenging to differentiate from atherosclerosis and may be misdiagnosed if intravascular imaging is not performed. In SCAD type 3, OCT is useful modality to identify the evidence of SCAD. Furthermore, superior resolution of OCT can visualize stent strut apposition and make stent optimization if stent implantation is considered in SCAD patients.
Overall, OCT is preferred to diagnose SCAD, not confirmed by coronary angiography, over IVUS in the SCAD patients presenting with AMI because of better resolution for identifying the evidence of SCAD, although there are potential limitations regarding shallow optical penetration and blood clearance.
References
1. Saw J. Spontaneous coronary artery dissection. Can J Cardiol. 2013; 29: 1027-1033.
2. Nishiguchi T, Tanaka A, Ozaki Y, et al. Prevalence of spontaneous coronary artery dissection in patients with acute coronary syndrome. Eur Heart J Acute cardiovasc Care. 2016; 5:263-270.
3. Saw J, Aymong E, Sedlak T, et al. Spontaneous coronary artery dissection: association with predisposing arteriopathies and precipitating stressors and cardiovascular outcomes. Circ Cardiovasc Interv. 2014; 7: 645-655.
4. Kim Y, Deharo P, Adlam D, Baumbach A, Johnson TW. The role of optical coherence tomography in decision making during the acute phase of spontaneous coronary artery dissection. Int J Cardiol Heart Vasc. 2017;14:6-7.
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