[Patent foramen ovale with a license to kill].

A patent foramen ovale (PFO) is present in about one of four, and one of its dangerous forms (large or associated with atrial septal aneurysm, Eustachian valve, or Chiari network) in one of twenty people. About 140 years ago, the PFO was shown to have the potential to result in death due to stroke and also myocardial infarction. The described decrease of the prevalence of a PFO with age may be a consequence of this. Therefore, it comes somewhat as a surprise that the PFO is taken rather lightly by the medical community. Percutaneous PFO closure with implantable devices has been around for over two decades and since then has proven to be the simplest and safest technique in interventional cardiology. Nonetheless, it is rarely applied and not recommended in current guidelines except for a few situations. Countless nonrandomised comparisons have invariably pointed to a clinical benefit of PFO closure in the secondary prevention of paradoxical cerebral events in patients with or without competitive reasons for stroke. Even a survival benefit of PFO closure was shown in a comparison over 10 years. However, the first three publications of randomised trials were not significant in the protocolled sense. PFO closure did reduce recurrent events compared to medical therapy by up to 80% but the statistical significance postulated was only reached in one of the three trials when the results were analyzed as treated or per predefined subgroups, like patients with atrial septal aneurysm, large PFO, or all PFO closure patients compared to treatment with acetylsalicylic acid only. Recently, a preplanned longer-term analysis of this trial and two additional randomised trials including higher risk PFOs reached the hypothesised statistical significance. This may be a turning point in the attitude towards PFO closure. In addition, PFO closure improves migraine and dyspnoea in certain patients. It appears, though, that it will take time until the full potential of PFO closure will be reflected in respective guidelines and reimbursement algorithms and adequately exploited by referring physicians (mostly neurologists) and interventional cardiologists. This reluctance will continue to cost innumerable preventable strokes, myocardial infarctions, and deaths around the world. The low risk of PFO closure must be weighed against even death if a PFO is left open; it is much more likely that one regrets not having closed a PFO than having closed it.