Clinical and imaging characteristics of PFO-related stroke with different amounts of right-to-left shunt.

Introduction: Right-to-left shunt (RLS) induced by a patent foramen ovale (PFO) is associated with an increased risk of cryptogenic stroke (CS). However, little is known about the relationship between the amount of RLS and the stroke pattern. In this study, we aimed to evaluate the distinct clinical features of PFO-related CS in different RLS degrees resulting from PFO.

Methods: This is a cohort study of 222 CS patients admitted to the Tongji Hospital from 1st May 2014 to 31st April 2017. All patients underwent contrast transcranial Doppler examination. And then, 121 (54.5%) were classified as non-RLS group, while 76 (34.2%) were classified as mild RLS group and 25 (11.3%) were large RLS group according to the number of micro-emboli signals. The groups were compared with respect to their clinical and neuroimaging characteristics.

Results: In terms of risk factors of stroke, the prevalence of hypertension was lower in mild group (p = 0.002). Regarding the infarct patterns in different CS patients, we found that the multiple cortical lesions were more frequently observed (p<0.001) with increasing RLS in DWI. Moreover, there was a rising trend in the proportion of small lesions (≤1 cm) with an increasing RLS (p < 0.01). And as RLS increased, the posterior circulation was more likely to be influenced (p < 0.05). In addition, the serum cholesterol concentration was lower in the large RLS group, compared to the non-RLS group (p = 0.003) and mild RLS group (p = 0.008). While the mean platelet volume (MPV) in mild group was significantly higher than that of non-RLS group (p = 0.013).

Conclusion: Patients with larger RLS show more infarction in posterior circulation, higher frequency of small lesions or multiple cortical lesions. The results of our study indicate that the infarct patterns might be a clue of PFO-related stroke.