Shunt related platelet activation in patients with patent foramen ovale

Background Patent foramen ovale (PFO) is present in one-third of the population and percutaneous PFO closure is recommended for secondary prevention of cryptogenic stroke. Prevalence of migraine in patients with PFO is reported to be notably higher, reaching up to 40% compared to 12% in the general population. Studies indicate that patients with migraine may exhibit a prothrombotic phenotype and percutaneous PFO closure has been associated with improvements in migraine symptoms; however, the underlying mechanism remains unclear. Aim The aim of this study was to investigate whether platelets are activated at the site of PFO due to a left-to-right shunt and whether this activation ceases after PFO closure. Methods Blood samples were taken from the right atrium before and immediately after PFO closure. Platelet activation was assessed using flow cytometry (Attune NxT, Thermo Fisher Scientific, MA, USA), with quantification of CD62P+ (P-selectin) as maker for platelet activation, following stimulation with adenosine diphosphate (ADP). Results A total of 49 patients were included, mean age was 53 (±11) years and 29 patients (59%) were male. Migraine headache was observed in 13 patients (26.5%). ADP stimulation revealed significantly higher CD62P+ count in samples from the right atrium before device closure, compared to samples collected immediately after closure (p<0.001), with mean reductions of 6.51% (Figure). Migraine patients exhibited higher baseline platelet activity (mean 62.58% CD62P+) compared to patients without migraine (mean 60.45% CD62P+). Conclusion These results suggest that patients with a left-to-right shunt, as occurs in PFO, have measurable changes in platelet activation that decrease significantly immediately after PFO closure. Preliminary data suggest higher platelet activity in migraine patients.