PFO or UFO
How Good Is Transesophageal Echocardiography in Identifying Patent Foramen Ovale as the Cause of a Cryptogenic Stroke?
Patent foramen ovale (PFO), which has been reported to be present in about one quarter of the adult population, is generally a hemodynamically insignificant interatrial communication.1 Since the advent of contrast echocardiography (echo), a strong association has been reported between cryptogenic stroke (CS) and PFO in patients <55 years of age.1,2 Although several studies have reported the association of PFO with CS in older patient populations, the association of atrial septal abnormalities and stroke in an older age group was not confirmed by a meta-analysis.1,3 Among 1100 stroke-free subjects (mean age, 69 years) in the Northern Manhattan Study evaluated by contrast transthoracic echo, PFO was detected in 164 (15%). After adjustment for demographics and risk factors, PFO was not found to be significantly associated with stroke.4
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In an enlightening article titled “Is Patent Foramen Ovale a Modifiable Risk Factor for Stroke Recurrence?” Kent and Thaler5 note that, “The evidence suggests that many patients with CS and PFO…have strokes that are unrelated to their PFO.” They introduced the concept of PFO propensity, defined as “the patient-specific probability of finding a PFO in a patient with CS on the basis of age and other risk factors”—including the absence of diabetes mellitus, hypertension, smoking history, coronary artery disease, and previous history of stroke or transient ischemic attack (TIA). The probability that a stroke is attributable to the PFO in a patient with a CS and a PFO is related nonlinearly to PFO propensity. The authors note that, “There is substantial heterogeneity in both PFO propensity and recurrence risk among patients with PFO and CS….”5
Transesophageal echocardiographic contrast study is probably the most sensitive diagnostic test for detecting a PFO, followed by transcranial Doppler and contrast transthoracic echo.1 Of …