Patent foramen ovale (PFO): is there life before death in the presence of PFO?

Patent foramen ovale (PFO) is an embryologic remnant with incomplete postnatal adhesion of the cardiac atrial septum primum and secundum. After birth, the prevalence of PFO decreases from about 35% at young to approximately 20% at old age. PFO has been associated with numerous conditions such as decompression illness in divers, migraine, high-altitude pulmonary oedema, cerebrovascular and coronary ischaemia, and obstructive sleep apnoea syndrome. PFO is the cause of intermittent atrial right-to-left shunt, and it can be the source of cardiac paradoxical embolism. So far, randomized controlled trials have not documented a reduced rate of cerebrovascular recurrent events in patients receiving PFO device closure as compared to those on medical treatment. The purpose of this article was to critically evaluate evidence on the pathophysiologic, clinical as well as prognostic relevance of PFO.