The evidence for causation of embolic stroke in any given person is, of course, circumstantial (for example, atrial fibrillation or carotid stenosis), and it seems reasonable that the presence of a PFO and a sizable interatrial shunt should similarly no longer result in the categorization of a stroke as cryptogenic.
One conclusion from previous trials of closure of patent foramen ovale is that the potential benefit from closure is determined on the basis of the positive characteristics of the PFO rather than on the basis of exclusionary factors that make a stroke cryptogenic. Restricting PFO closure entirely to patients with high-risk characteristics of the PFO may perhaps be too conservative, but the boundaries of the features that support the procedure are becoming clearer.
Dr. Allan H. Ropper is deputy editor of the New England Journal of Medicine. These comments are taken from an accompanying editorial (N Engl J Med. 2017; 377:1093-5). He had no conflicts of interest to declare.