Relation Between Patent Foramen Ovale and Stroke

ABSTRACT & COMMENTARY
Source: Petty GW, et al. Patent foramen ovale in patients with cerebral infarction. A transesophageal echocardiography study. Arch Neurol 1997;54:819-822.

Patent foramen ovale (pfo) with or without an interatrial septum aneurysm considered by some to be a common "occult" cardiopathy associated with cardioemboli stroke, is a common incidental finding in healthy young adults and not emboligenic by itself. The association between PFO and ischemic stroke remains controversial; therefore, Petty and colleagues sought to determine the frequency of PFO among various subtypes of cerebral infarction.

One hundred sixteen ischemic stroke patients consecutively referred for transesophageal echocardiography (TEE) during a six-month period were studied. A PFO was detected in 37 (32%) of this patient group. The mean age (± SD) of patients with PFO, 60 + 3 years, was not different from the age of those without a PFO (6 + 2 years; P = NS). PFO was more frequent among men (39%) than women (20%) (P = 0.03).

Patients with PFO had a lower frequency of the common risk factors for ischemic stroke, atrial fibrillation (P = 0.04), diabetes mellitus (P = 0.04), hypertension (P = 0.05), and peripheral vascular disease (P = 0.05) than those patients without PFO.

PFO was found in 22 of 55 (40%) patients with cerebral infarcts of uncertain cause and in 15 of 61 (25%) of those with infarcts of known cause (P = NS). (See Table.)

In 68 patients, the Valsalva maneuver produced a right to left or a bidirectional shunt confirming the potential of PFO to allow paradoxical embolism. Nineteen of 38 patients (50%) with infarcts of uncertain cause had such shunts, but only six of 30 (20%) patients with infarcts of known cause had a positive Valsalva maneuver (P = 0.01). Nevertheless, the authors did not find an overrepresentation of clinical markers for paradoxical embolism, deep vein thrombosis, pulmonary embolism, prior stroke, or TIA in patients with PFO.

Table

Frequency of PFO Among 116 Patients with Cerebral Infarction

Type of Infarct Patients with PFO (%)

Infarcts of unknown cause (n = 55) 40

Infarcts of known cause (n = 61) 25

Cardioembolic (n = 29) 21

Atherothrombotic (n = 12) 25

Lacunar (n = 15) 40

COMMENTARY

Given the high frequency of PFO in autopsy studies—up to 27% in one report (Hayes PT, et al. Mayo Clin Proc 1984;59:17-20)—and the overrepresentation of PFO among patients with infarcts of uncertain cause, PFO may be an important and under-recognized mechanism of ischemic stroke. In this study, the high frequency of PFO among patients with infarcts of known cause (see Table) and the low frequency with which markers of paradoxical embolism were found in patients with PFO and stroke raises questions about the importance of PFO as a stroke risk factor. Therefore, for the present, it seems prudent to consider paradoxical embolism via a PFO as a cause of stroke only when the patient also has a documented peripheral venous thrombosis or when stroke was triggered by a Valsalva maneuver. In the absence of such clinical markers, the discovery of a PFO on TEE in a patient with a recent cerebral infarct should be considered more an incidental finding than the cause of stroke, and the clinician must search for other causes. —jjc