Abstracts & Commentary
Synopsis: Neither the presence of PFO nor its size or the presence of atrial septal aneurysm increased the risk of subsequent cerebrovascular events or death.
Source: Homma S, et al. Circulation. 2002;105: 2625-2631.
Although patent foramen ovale (pfo) has been associated with stroke, little data exist about the efficacy of treatment for this condition. Thus, 2 recent studies, one of medical therapy, the other of transcatheter closure, are of interest. Homma and colleagues, representing the PFO in cryptogenic stroke study (PICSS) investigators, reports on a 42-center study that assessed the benefit of aspirin vs. warfarin in stroke patients with or without PFO as defined by transesophageal echocardiography (TEE). In the treatment comparison study 630 stroke patients were entered, of whom 265 had cryptogenic stroke. PFO was present in 203 of the 630 (34%). The patients were followed for 2 years; the primary end point was recurrent stroke or death. The incidence of PFO was higher in cryptogenic stroke patients (39%) vs other causes of stroke (30%; P < .02) and large PFOs were even more common in cryptogenic stroke (20% vs 10%; P < .001). There was no difference in the time to the primary end point between patients with or without PFO and it was not a multivariate predictor of the primary outcome. Similar results were observed in the cryptogenic group and in the large vs. small PFO groups. The warfarin-treated group had fewer events than the aspirin group; this was true in the cryptogenic group with or without PFO. All the above results persisted when transient ischemic attacks (TIA) was added to the end points. Homma et al concluded that on medical therapy neither the presence of PFO nor its size or the presence of atrial septal aneurysm increased the risk of subsequent cerebrovascular events or death.
Comment by Michael H. Crawford, MD
This study demonstrates that cryptogenic stroke is associated with PFOs, especially large ones, which confirms the paradoxic embolism theory of this association. Consequently, if the development of thrombi in other parts of the venous system can be prevented, stroke could be prevented despite the PFO. The results of this study support this hypothesis. On medical therapy with either warfarin or aspirin in these stroke patients, recurrent stroke or death was the same whether PFO was present and this result persisted if only the cryptogenic stroke patients were analyzed or if TIA was included as an end point. Of interest in the cryptogenic stroke group, there was no difference in efficacy between warfarin and aspirin therapy. This suggests that even in cryptogenic patients with PFO, stroke may be caused by arterial events. Now that there are effective devices for percutaneous closure of PFO’s, can the recurrent event rate be reduced even further?
Dr. Crawford is Professor of Medicine, Mayo Medical School; Consultant in Cardiovascular Diseases, and Director of Research, Mayo Clinic, Scottsdale, AZ.
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