Risk of a residual shunt following patent foramen ovale closure: A myth?

This letter challenges the prevailing assumption that residual shunt following patent foramen ovale (PFO) closure is a primary driver of recurrent stroke risk. While residual shunt has been associated with higher rates of neurologic events in observational studies, the author argues that this relationship is not supported by randomized data and may be confounded by diagnostic ambiguity, particularly the inclusion of transient ischemic attack alongside stroke outcomes. The complex pathophysiology of PFO-related stroke, requiring thrombus formation, transient right-to-left shunting, and specific anatomic factors, is often substantially mitigated by the closure procedure itself. Emerging evidence suggests that device-related factors, including incomplete endothelialization and altered atrial hemodynamics, may independently contribute to thromboembolic risk after closure, irrespective of residual shunting. The letter proposes that residual shunt may be an inadequate surrogate endpoint and that clinical focus should instead remain on true stroke recurrence. It further cautions against routine re-intervention to eliminate residual shunt, advocating instead for consideration of prolonged antithrombotic therapy and alternative closure strategies, such as suture-based approaches, which may avoid device-related complications. Overall, this perspective calls for a reassessment of current paradigms in post-PFO closure management and outcome evaluation.