Nonstenotic carotid artery plaque in patients with cryptogenic stroke after ICM: A sub-analysis of the LOOK study

To investigate whether differences in carotid plaque size between the ipsilateral and contralateral sides of the stroke site influence the detection of atrial fibrillation (AF) after cryptogenic stroke (CS).

We analyzed data from the prospective, multicenter LOOK Study, which enrolled patients with CS diagnosed and monitored using an implantable cardiac monitor (ICM). The study included patients with unilateral anterior circulation cerebral infarction, divided by whether AF was detected within 6 months of ICM implantation. Carotid plaque size was compared between the ipsilateral and contralateral sides of the stroke site.

Ninety-seven patients (32 women; median age 70 years; median NIHSS 3) were included; 21 developed AF. Among patients without detected AF, carotid plaques ≥1.4 mm were significantly more frequent on the ipsilateral side compared to the contralateral side (27/76 vs. 18/76, p = 0.022). Conversely, patients with detected AF showed no significant difference in plaque size between ipsilateral and contralateral to the stroke site (1.5 mm vs. 1.7 mm, p = 0.754). For patients with an ipsilateral plaque ≥1.4 mm, an ipsilateral-to-contralateral plaque size ratio of ≥1.2 demonstrated a specificity of 75 % and sensitivity of 63 % for predicting no detected AF (area under the curve = 0.727, 95 % CI 0.543-0.911, p = 0.025).

This study demonstrated that carotid plaque distribution patterns differ significantly between CS patients with and without detected AF. An ipsilateral carotid plaque ≥1.4 mm and a size ratio ≥ 1.2 may predict no detected AF, potentially indicating an embolic source other than AF.