Russian Registry of Endovascular Closure of Patent Foramen Ovale

Ischemic stroke is the fifth most common cause of death and the leading cause of disability among adult patients worldwide. Cryptogenic stroke is a very broad term that applies in cases of incomplete evaluation, with multiple "competing" causes, and in situations where the cause could not be identified during evaluation. This type of stroke has been termed embolic stroke from an undetermined source, or ESUS (Embolic Stroke of Undetermined Source). Possible causes of ESUS include cardiopathies, including isolated atrial myocardial damage, atherosclerotic lesions of the extra- and intracranial arteries and aortic arch (these 3 causes are the most common), as well as patent foramen ovale (PFO), heart defects, oncology, and concealed atrial fibrillation. According to a 2015 observational study by LiL. et al. approximately one third of all ischemic strokes are considered cryptogenic. An important contribution to the development of cryptogenic stroke according to the data of a number of authors is made by an unenlarged patent foramen ovale (PFO). Once the relationship between the development of cryptogenic stroke and the PFO is established, the stroke is considered to be PFO-associated.

According to the literature, the incidence of a PFO in adult patients ranges from 20% to 35%. The distinguishing feature of a PFO from an interatrial septal defect is impaired fusion of the primary and secondary septum, rather than a deficiency.

There are various theories for the development of cryptogenic stroke in patients with a PFO. The most popular is the presence and migration of thrombus from the inferior vena cava system: predominantly the veins of the lower extremities, but also the pelvic veins. It is also possible to develop thrombus in the PFO channel due to the change from laminar to turbulent blood flow directly in the tunnel of the unclosed PFO. This mechanism of cryptogenic stroke development is more theoretical and is not currently confirmed by the literature.

In addition to the development of cryptogenic strokes in patients with a PFO there is a risk of thromboembolism of other organs and systems. According to the literature, thrombus migration through the PFO may be the cause of occlusion of arteries of the intestine, lower and upper extremities. Clinical cases of thrombus migration through PFO have been described, which led to occlusion of coronary arteries and development of acute myocardial infarction with ST-segment elevation.

In the presence of cryptogenic stroke or other thromboembolism in patients with an unclosed PFO, the contribution of the PFO to the development of vascular catastrophe is evaluated. The Risk of Paradoxal Embolism (RoPE) scale was created. A high total score on the scale indicates a high probability of a relationship between PFO and cryptogenic stroke. The scale is a simple tool for clinicians, but in the European Society of Cardiology consensus document on the treatment of patients with PFO, even a low score on this scale is not a contraindication for endovascular treatment of patients with PFO.