The Fate of the External Carotid Artery after Carotid Artery Stenting. A Follow-up Study with Duplex Ultrasonography

Kaplan Meier estimates of ECA stenosis free survival: ipsilateral ECA vs contralateral ECA (N=312) (p<0.001). Time schedule: BASELINE – 3m-12m-24m-36m-48m-60m.

Ipsilateral: 67.3% (baseline) – 50.9% – 43.6% – 35.3% – 31.8% – 27.7% – 26.0%. The Standard Error (SE) was 0.0296, 0.0297, 0.0296, 0.0294, 0.0301 and 0.0329 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 194 with a mean stenosis free follow-up of 23.3 months 95% CI (20.2–26.3) SE 1.56.

Contralateral: 70% (baseline) – 68.8% – 62.4% – 58.5% – 57% – 54.2% – 52.9%. The SE was 0.0274, 0.0289, 0.0299, 0.0303, 0.0320, and 0.0336 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 124 with a mean stenosis free follow-up of 36.5 months 95% CI (33.3–39.7) SE 1.64.

Kaplan Meier estimates of ECA stenosis free survival: ipsilateral non-overstented ECA (N=54) vs ipsilateral overstented ECA (N=238) (p=0.0004). Time schedule: BASELINE – 3m-12m-24m-36m-48m-60m.

Ipsilateral (All): 67.3% (baseline) – 50.9% – 43.6% – 35.3% – 31.8% – 27.7% – 26.0%. The Standard Error (SE) was 0.0296, 0.0297, 0.0296, 0.0294, 0.0301 and 0.0329 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 194 with a mean stenosis free follow-up of 23.3 months 95% CI (20.2–26.3) SE 1.56.

Non-overstented: 79.6% (baseline) – 75.0% – 70.1% – 62.9% – 57.1% – 46.4% – 46.4%. The SE was 0.0608, 0.0658, 0.0711, 0.0752, 0.0827 at 3 to 48 months respectively. Number of events (stenosis≥50%) was 23 with a mean stenosis free follow-up of 37.5 months 95% CI (30.3–44.7) SE 3.67.

Overstented: 64.6% (baseline) – 46.6% – 38.6% – 29.8% – 26.8% – 24.1% – 22.1%. The SE was 0.0327, 0.0323, 0.0316, 0.0312, 0.0318, 0.0350 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 167 with a mean stenosis free follow-up of 20.6 months 95% CI (17.3–23.9) SE 1.68.

Kaplan Meier estimates of ECA stenosis free survival in selected patients with no stenosis at baseline: ipsilateral ECA vs contralateral ECA (N=167) (p=0.0043). Time schedule: BASELINE – 3m-12m-24m-36m-48m-60m.

Ipsilateral: 0% (baseline) – 75.4% – 64.7% – 52.4% – 47.2% – 41.1% – 38.5%. The Standard Error (SE) was 0.0327, 0.0373, 0.0406, 0.0418, 0.0444 and 0.0492 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 82 with a mean stenosis free follow-up of 36 months 95% CI (32.1–39.8) SE 1.97.

Contralateral: 0% (baseline) – 90.1% – 82.6% – 76.8% – 74.0% – 69.6% – 67.3%. The SE was 0.0323, 0.0345, 0.0367, 0.0377, 0.0401 and 0.0442 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 50 with a mean stenosis free follow-up of 43.6 months 95% CI (39.7–47.5) SE 2.0.

Kaplan Meier estimates of ECA stenosis free survival in patients with no ECA stenosis at baseline: ipsilateral non-overstented ECA (N=37) vs ipsilateral overstented ECA (N=139) (p=0.004). Time schedule: BASELINE – 3m-12m-24m-36m-48m-60m.

Ipsilateral (All N=167): % (baseline) – 75.4% – 64.7% – 52.4% – 47.2% – 41.1% – 38.5%. The Standard Error (SE) was 0.0327, 0.0373, 0.0406, 0.0418, 0.0444 and 0.0492 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 82 with a mean stenosis free follow-up of 36 months 95% CI (32.1–39.8) SE 1.97.

Non-overstented: 0% (baseline) – 94.1% – 88.1% – 78.9% – 71.8% – 58.3% – 58.3%. The SE was 0.0339, 0.0579, 0.0720, 0.0838 and 0.102 at 3 to 48 months respectively. Number of events (stenosis≥50%) was 10 with a mean stenosis free follow-up of 48 months 95% CI (41.8–54.8) SE 3.32.

Overstented: 0% (baseline) – 71.1% – 58.9% – 46.2% – 41.5% – 37.3% – 34.2%. The SE was 0.0382, 0.0428, 0.0462, 0.0471, 0.0492, and 0.0553 at 3 to 60 months respectively. Number of events (stenosis≥50%) was 70 with a mean stenosis free follow-up of 33.4 months 95% CI (29.0–37.8) SE 2.24.

During follow-up in 48 patients stenosis ≥50% of the ipsilateral Internal Carotid Artery occurred. The incidence of in-stent recurrent stenosis (≥50%) therefore was 15,5% in the present study after a mean follow-up of 44 months.

The correlation between ICA and ECA reached significance when patients with ECA stenosis at baseline were included (Chi-Square test; ρ=0.026). If patients with a preprocedural ≥50% ACE stenosis were abandoned from analysis the correlation was non significant (ρ=0.09).