Purpose: To examine if excessive in-stent neointimal formation causing a subcritical stenosis may indicate enhanced vascular reactivity in response to injury, thus predicting late cardiovascular events.
Methods: One hundred consecutive patients (64 men; median age 71 years) with high-grade internal carotid artery stenoses (68 asymptomatic, 32 symptomatic) underwent carotid artery stenting (CAS). High-sensitivity C-reactive protein (hs-CRP) was measured before CAS. Patients were monitored with duplex ultrasound for excessive in-stent neointimal formation (flow-compromising lumen diameter reduction >/=50%), critical restenosis (>/=70%), or the occurrence of late major adverse cardiovascular events (MACE) defined as myocardial infarction (MI), stroke, and death occurring later than 30 days poststenting.
Results: Over a median 23-month follow-up, excessive neointimal formation was observed in 14 (14%) patients, restenosis in 2 (2%), and 30 late MACE in 25 [25%: 4 MIs, 2 ipsilateral strokes (in the patients with restenosis), 8 contralateral strokes, and 16 cardiovascular deaths]. Cumulative MACE-free survival rates at 6, 12, and 24 months were 92%, 84%, and 77%, respectively. Baseline hs-CRP levels were associated both with neointimal hyperplasia (p=0.024) and MACE (p=0.021). Patients with excessive neointimal formation exhibited a significantly increased adjusted risk for MACE (hazard ratio 3.56, p=0.010).
Conclusions: Excessive in-stent neointimal formation after CAS indicates an increased risk for late MACE, potentially reflecting a state of exaggerated vascular reactivity in response to injury. Inflammation, which is associated both with neointimal hyperplasia and MACE, seems a common characteristic of different vascular pathologies.