How often is patent foramen ovale an innocent bystander?

Patent foramen ovale (PFO) is a risk factor for cryptogenetic stroke; its closure should be considered in selected patients. It is not always clear whether symptoms (presyncope, paresthesia) apparently due to paradoxical embolism are related with other cardiovascular disorders such as arrhythmias. Flecainide administration for post-PFO-closure supraventricular arrhythmias can unmask a latent undiagnosed Brugada syndrome.