Abstract WP401: Residual Shunting Post PFO Closure is Associated With Increased Long-term Risk of Recurrent Stroke

Abstract

Background: Patent foramen ovale (PFO) is an independent risk factor for ischemic stroke, and recent clinical trials have shown long-term benefit of PFO closure. We previously found PFO may increase the risk of stroke due to right-to-left shunting, resulting in venous contamination of arterial circulation, with elevated neurovascular mediators such as homocysteine. However, in clinical practice, residual blood shunting can be observed in ~10% of patients post PFO closure, with unclear significance. Here we prospectively investigated the long-term influence of residual shunting on patient outcome. Method: 1018 PFO stroke patients s/p PFO closure from several medical centers were prospectively recruited in accordance with IRB protocol and followed up to 7 years. Result: While closure rate at our center is much lower (<5%), overall closure rate of patients from all major referral centers range between 5-14%. Patients with compete PFO closure (86%) developed higher event-free probability from recurrent TIA/stroke compared to those with residual shunting (14%) (Figure1A, p = 0.001). The risk of recurrent stroke depended on residual shunt size with lower event-free probability in larger shunting (Figure 1B, p = 0.002). Conclusion: Consistent with clinical trials, our prospective observational study suggests complete PFO closure results in lower risk of stroke recurrence. Patients with residual shunting (incomplete PFO closure) may face continued risk, though the overall risk of stroke recurrence is very low. PFO-related shunting appears to be critical in the pathophysiology of recurrent stroke.