Abstract TP127: Morphology of Acute Symptomatic Intracranial Atherosclerotic Plaques

Introduction: Intracranial atherosclerotic disease (ICAD) is an important subtype of ischemic stroke worldwide. Understanding the morphologic features of acutely symptomatic plaques may help identify vulnerable lesions and guide treatment.

Methods: We prospectively recruited 170 patients (median age = 60.5 years) with acute ischemic stroke attributed to ICAD (≥60% stenosis) confirmed by 3-dimensional rotational angiography (3DRA) from May 2007 to Feb 2017. We evaluated the morphology of the index atherosclerotic plaques in 3DRA. We categorized plaques with irregular or ulcerated surface as complicated plaques. We compared the morphological features of smooth and complicated plaques.

Results: The median interval between symptom onset and 3DRA exam was 22 days. The median severity of luminal stenosis was 75%. The median maximum plaque thickness was 1.3mm and lesion length was 8.8mm. The plaque surface was smooth, irregular, or ulcerated in 50 (29.4%), 90 (52.9%), and 27 (15.9%) cases, respectively. The point of maximum stenosis was located in the distal end of the lesions in 88 (51.8%) cases. A majority (85.3%) of the plaques were eccentric. The median angulation between the upstream plaque shoulder and an imagined “normal” vessel wall (assuming there were no plaque) was 33.4°. Overall, complicated plaques led to more severe luminal stenosis (medians 77.0 vs 73.0%; p=0.032); the lesions were longer (medians 10.0 vs 6.9 mm; p<0.001), and the upstream shoulders were steeper (median angles 34.3 vs 28.0°; p=0.048) than smooth plaques.

Conclusions: We identified the morphologic pattern of symptomatic high-grade intracranial atherosclerotic plaques during the acute phase that are significantly different between smooth and complicated plaques. The current findings warrant a comparison with silent ICAD lesions for validation.