Comparison of clinical and biological differences between patent foramen ovale subtypes in ischemic stroke

Backgrounds: The patent foramen ovale (PFO) is an atrial septal tunnel with a flap-like opening, causing a right-to-left shunt (RLS) between the atrial chambers. There are few studies on ischemic stroke characteristics based on PFO subtypes. In this study, we investigated whether there are differences in clinical characteristics, RLS amount, and the etiology of stroke defined by the Trial of ORG 10,172 in Acute Stroke Treatment (TOAST) classification between PFO subtypes. Methods: We retrospectively analyzed consecutive ischemic stroke patients with PFO who were admitted to the Jeonbuk National University Hospital from November 2013 to February 2015, and performed a microbubble test to detect RLS. The patients were divided into two groups according to RLS characteristics: constant RLS group and provoked RLS group. We compared the clinical characteristics and degree of RLS between the PFO subtypes. Results: Out of 144 ischemic patients evaluated in this study, 83 (58%) were classified into the constant RLS group and 61 (42%) into the provoked RLS group. The proportion of microembolic signal (MES) grades 3 and 4 was significantly higher in the constant RLS group than in the provoked RLS group. There were no statistical differences in the distribution of TOAST classification between the two groups. Conclusion: The constant RLS group showed a higher proportion of high-grade MES than the provoked RLS group.