Conflict of interest
The authors declare no potential conflict of interest.
Patent foramen oval (PFO) is an anatomical variant of the interatrial septum. The two anatomical components of PFO, septum secundum and septum primum, can act as a flap valve in almost 25% of adult general population, allowing a transient or continuous right-to-left shunt (after a Valsalva maneuver or when the right atrial pressure exceeds the left atrial pressure during a short interval of cardiac cycle)1. In these patients, PFO can act as a conduit for paradoxical embolization (reported to be between 3.4% and 11%1) and ischemic left circulation embolism. Patent foramen oval has highly variable anatomical morphology with respect to size, tunnel length, redundancy of septum, lipomatous hypertrophy, thickness of septum secundum and relationship to neighboring structures1. The morphology of the interatrial septum can be more complicated when PFO associates defects such as atrial septal aneurysm and atrial septal defects. It can be associated with embolic strokes of undetermined source (ESUS) - a subcategory of ischemic cryptogenic stroke ranging from 9 to 25% of all stroke patients, migraine, peripheral embolism, platypnea-orthodeoxia syndrome or Alzheimer’s dementia2. ESUS type of cryptogenic strokes (without an identifiable etiology) is a clinical entity, which requires an extensive and accurate diagnostic work-up. It was defined as ischemic stroke that is not lacunar, detected by specific imaging modality (computer-tomography or magnetic resonance imaging). In addition, it comprise excluding the extracranial or intracranial atherosclerosis causing ≥50% luminal stenosis in arteries supplying the area of ischemia, major risk cardio-embolic source of embolism or other specific cause of stroke identified (e.g., arteritis, dissection, migraine/vasospasm, or drug abuse).
The study of Polat F et al.3 analyzed atrial septum, PFO and accompanying anatomical variant of right atrial structures in migraine and ESUS patients. In addition, they compared RoPe and High-risk PFO scores (two scores based on clinical and anatomical criteria to identify high-risk PFO) in migraine and ESUS patients. In this study, the patients with ESUS were older, with a higher prevalence of diabetes and hypertension and exhibited notable echocardiographic differences (higher pulmonary artery systolic pressure, increased microbubble crossings through the interatrial septum, and longer PFOs). They have also a slightly elevated High-risk PFO score. In this study, both scores were not different between ESUS and migraine group, which means that, practically, the presence of high-risk criteria alone may not be sufficient to differentiate between ESUS and migraine patients with PFO. This is underlie by another result of this study: ESUS patients have had a slightly elevated High-risk PFO score. The patients with migraine and PFO exhibit a higher prevalence of active smoking, which means that tobacco use can affect migraine patterns3. The study of Polat F et al identified distinctive features in patients with PFO, ESUS, and migraine, putting other pieces in the puzzle of cryptogenic stroke/transient ischemic attack. It is essential because it could help to stratify PFO with ESUS patients (which seems to be a very inhomogeneous population) who are most likely to benefit from an aggressive therapeutic approach. Symptoms are important arguments in every pathology that impose treatment.