Optical coherence tomography imaging in asymptomatic patients with carotid artery stenosis




Abstract


Assessment and treatment plan for asymptomatic patients with carotid stenosis are based on angiography at the present time. However, angiography or other imaging modalities are limited with their resolution to detect high-risk plaque features. Intravascular optical coherence tomography (IVOCT) recently emerged as a novel imaging modality with a unique resolution to identify vulnerable plaque characteristics. We report use of IVOCT in two separate asymptomatic patients with carotid stenosis with two different plaque types.



Introduction


Atherosclerosis of the carotid artery is the culprit in 15%–20% of strokes . Most of these strokes occur in patients who were previously asymptomatic . The severity of the carotid lesion purely based on angiography remains a poor predictor of clinical outcome . Several studies have suggested that stroke risk may be best predicted by plaque morphology in asymptomatic patients . Intravascular optical coherence tomography has recently emerged as a novel imaging modality with an axial resolution of 10 μm, higher than any other imaging technique with its ability to detect thin-cap fibroatheroma (TCFA), intraluminal thrombus, calcification and inflammation in the vessel wall . It is possible that presence of TCFA or large lipid pools may predict embolic debris and events during carotid artery stenting. We report the use of IVOCT in two separate asymptomatic patients with severe carotid artery stenosis, with and without high-risk features for distal embolization.





Case 1


A 78-year-old male with history of coronary artery disease, hypertension and diabetes underwent carotid angiography for further evaluation of an abnormal carotid duplex examination. Carotid angiography demonstrated severe left internal carotid stenosis (LICA) by NASCET criteria ( Fig. 1 A ). Patient was accepted as high-surgical risk for carotid endarterectomy (CEA) because of low ejection fraction (EF < 30%) and abnormal stress test. IV anticoagulation was given. Using 2.7 French (Fr) C7 Dragonfly catheter (frequency domain OCT (FDOCT), St. Jude Medical, St. Paul, MN) IVOCT imaging of the lesion was performed following deployment of the proximal flow device MoMa (Medtronic Inc. Minneapolis Minn.) as well as a distal embolic protection filter (DEPF) (5.5 mm NAV-6 Filterwire; Abbott Vascular, Redwood City, CA) with hand injection of 20 ml of contrast ( Fig. 1 B, Video 1). IVOCT imaging demonstrated a rather smooth and concentric lesion without critical ulceration, TCFA or intraluminal thrombus (Minimum Luminal Diameter (MLD) of 1.06 mm ( Fig. 1 D), reference diameter of 5.6 mm) ( Fig. 1 C, E). The lesion was predilated with a 4.0 × 20 mm balloon and deployment of a tapered 6 × 8 mm 3 cm Xact carotid stent (Abbott Vascular). Post-dilation with a 5 mm balloon was performed. Aspiration of PPD guide did not reveal any debris. Repeat IVOCT imaging showed optimal apposition of stent to intima with no significant residual stenosis or tissue prolapse. Next, DEPF was removed with recovery sheath with no embolic material detected in the filter. There were no vascular or neurological complications. Patient was discharged next day on dual antiplatelet therapy.




Fig. 1


(A–F). A. Selective LICA angiography shows severe stenosis at its cervical portion (lower right white arrow). Proximal embolic protection device, MOMA was deployed in the left external carotid artery (lower left white arrow). Distal embolic protection filter was deployed in the petrous portion of LICA (higher white arrow). IVOCT imaging catheter was placed distal to the lesion (black arrow). B. OCT pull back was performed using 20 ml of contrast hand injection that confirmed the severe stenosis of LICA (white arrow). OCT imaging also demonstrated a rather smooth and concentric lesion with no critical ulceration. C. Proximal and distal vessel reference diameters were measured (Proximal reference diameter: 5.2 mm). D. MLD at the lesion site was measured as 1.06 mm). E. Lesion length was also able to be measured on the longitudinal pull back. F. LICA angiography post-stenting and dilation showed well deployed stent with minimal residual stenosis and good distal flow.





Case 1


A 78-year-old male with history of coronary artery disease, hypertension and diabetes underwent carotid angiography for further evaluation of an abnormal carotid duplex examination. Carotid angiography demonstrated severe left internal carotid stenosis (LICA) by NASCET criteria ( Fig. 1 A ). Patient was accepted as high-surgical risk for carotid endarterectomy (CEA) because of low ejection fraction (EF < 30%) and abnormal stress test. IV anticoagulation was given. Using 2.7 French (Fr) C7 Dragonfly catheter (frequency domain OCT (FDOCT), St. Jude Medical, St. Paul, MN) IVOCT imaging of the lesion was performed following deployment of the proximal flow device MoMa (Medtronic Inc. Minneapolis Minn.) as well as a distal embolic protection filter (DEPF) (5.5 mm NAV-6 Filterwire; Abbott Vascular, Redwood City, CA) with hand injection of 20 ml of contrast ( Fig. 1 B, Video 1). IVOCT imaging demonstrated a rather smooth and concentric lesion without critical ulceration, TCFA or intraluminal thrombus (Minimum Luminal Diameter (MLD) of 1.06 mm ( Fig. 1 D), reference diameter of 5.6 mm) ( Fig. 1 C, E). The lesion was predilated with a 4.0 × 20 mm balloon and deployment of a tapered 6 × 8 mm 3 cm Xact carotid stent (Abbott Vascular). Post-dilation with a 5 mm balloon was performed. Aspiration of PPD guide did not reveal any debris. Repeat IVOCT imaging showed optimal apposition of stent to intima with no significant residual stenosis or tissue prolapse. Next, DEPF was removed with recovery sheath with no embolic material detected in the filter. There were no vascular or neurological complications. Patient was discharged next day on dual antiplatelet therapy.


Nov 14, 2017 | Posted by in CARDIOLOGY | Comments Off on Optical coherence tomography imaging in asymptomatic patients with carotid artery stenosis
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