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.