Safety of embolic protection device-assisted and unprotected intravascular ultrasound in evaluating carotid artery atherosclerotic lesions

BACKGROUND: Significant atherosclerotic stenosis of internal carotid artery (ICA) origin is common (5–10% at ≥60 years). Intravascular ultrasound (IVUS) enables high-resolution (120 μm) plaque imaging, and IVUS-elucidated features of the coronary plaque were recently shown to be associated with its symptomatic rupture/thrombosis risk. Safety of the significant carotid plaque IVUS imaging in a large unselected population is unknown. MATERIAL/METHODS: We prospectively evaluated the safety of embolic protection device (EPD)-assisted vs. unprotected ICA-IVUS in a series of consecutive subjects with ≥50% ICA stenosis referred for carotid artery stenting (CAS), including 104 asymptomatic (aS) and 187 symptomatic (S) subjects (age 47–83 y, 187 men). EPD use was optional for IVUS, but mandatory for CAS. RESULTS: Evaluation was performed of 107 ICAs (36.8%) without EPD and 184 with EPD. Lesions imaged under EPD were overall more severe (peak-systolic velocity 2.97±0.08 vs. 2.20±0.08m/s, end-diastolic velocity 1.0±0.04 vs. 0.7±0.03 m/s, stenosis severity of 85.7±0.5% vs. 77.7±0.6% by catheter angiography; mean ±SEM; p<0.01 for all comparisons) and more frequently S (50.0% vs. 34.6%, p=0.01). No ICA perforation or dissection, and no major stroke or death occurred. There was no IVUS-triggered cerebral embolization. In the procedures of (i) unprotected IVUS and no CAS, (ii) unprotected IVUS followed by CAS (filters – 39, flow reversal/blockade – 3), (iii) EPD-protected (filters – 135, flow reversal/blockade – 48) IVUS+CAS, TIA occurred in 1.5% vs. 4.8% vs. 2.7%, respectively, and minor stroke in 0% vs. 2.4% vs. 2.1%, respectively. EPD intolerance (on-filter ICA spasm or flow reversal/blockade intolerance) occurred in 9/225 (4.0%). IVUS increased the procedure duration by 7.27±0.19 min. CONCLUSIONS: Carotid IVUS is safe and, for the less severe lesions in particular, it may not require mandatory EPD use. High-risk lesions can be safely evaluated with IVUS under flow reversal/blockade.