Patent foramen ovale (PFO) is present in a significant proportion of young patients with stroke of undetermined etiology, but is not always causal. Therefore, classifications (RoPE, PASCAL) have been developed to determine the probability that PFO is the stroke cause. However, the presence of an initial arterial occlusion as a prediction factor was not studied when these classifications were built. Our aim was to evaluate the presence of arterial occlusion in young patients with stroke of undetermined etiology with/without high-risk PFO.

From a prospectively-built monocentric database, we identified patients aged≥18 to<60-years with strokes of undetermined etiology and complete etiological work-up, including transesophageal echocardiography. We divided patients in two groups: (i) with high-risk PFO [i.e. PFO with large interatrial shunt (>30 microbubbles) or associated with atrial septal aneurysm] and (ii) with low-risk/without PFO. We recorded the presence of arterial occlusion and large vessel occlusion (LVO) in the acute phase.

We included 96 patients; 55 (57%) had high-risk PFO. Their median age was 48 (40–52) years, and 28 (29%) were women. The percentages of patients with arterial occlusion and with LVO were lower in the high-risk PFO group than in the low-risk/without PFO group: 11 (20%) versus 19 (46%) (P=0.008), and 5 (9%) versus 15 (37%) (P=0.002), respectively. There was no difference in the median RoPE score between groups (P=0.30).

The presence of LVO could represent a “red flag” of PFO causality in stroke of undetermined etiology, and could be implemented in future PFO-related stroke classifications.