PFO Closure May Lower Stroke, Migraine Incidence
Percutaneous patent foramen ovale (PFO) occlusion may provide a mechanism to reduce passage of thromboses over the distal pathway, which, in turn, may prevent recurrent stroke and lower the risk of migraine.
One hundred forty patients with cryptogenic stroke between 2001 and 2006 who underwent PFO occlusion with a CardioSeal (NMT Medical) implant had no recurrent stroke or transient ischemic attack (TIA), said Jonathan Tobis, MD, Professor of Medicine at the University of California, Los Angeles.
There were two cases of groin bleeding among the 140 patients, and one device was explanted due to fears of embolization.
“The risk of a permanent PFO occlusion device must be less than the risk of recurrent stroke,” Tobis stressed.
These results need to be verified in randomized clinical trials, he added.
Supporting evidence
In separate observational studies, the incidence of stroke, death or TIA is reported to be 3% in patients who have undergone PFO closure compared with 4.9% in patients who have not undergone PFO occlusion.
Both the RESPECT trial, using the Amplatzer (AGA Medical) device, and the CLOSURE trial, examining the CardioSeal device, are enrolling patients aged 18 to 60 years with PFO who have an abnormal MRI or CT result. Patients will receive
either PFO occlusion or medical intervention with PFO occlusion.
The risk of recurrent stroke or death within three years is more than three times greater in patients older than 65 with PFO compared with no PFO. The risk of recurrent stroke in patients older than 65 with PFO is also greater than those in any other age range (Figure 1).
These risks appear independent of other risk factors, notably hypertension, diabetes or high cholesterol. This suggests that PFO may be more important than concurrent atheroma in patients with PFO, Tobis said.
PFO and migraine
Recent studies have reported that about 12% of the population suffers from migraine headaches, which disproportionately affect women. The incidence of migraine with aura in patients with cryptogenic stroke and PFO is about 52%, and the incidence of migraine with aura in patients with PFO is about 48%. In addition, the rate of MRI lesions is 13 times higher in patients who experience migraines than patients without migraines, Tobis said.
It is this last fact that should pique the interest of cardiologists, he said. A more recent understanding of migraine defines the condition as “a wave of spreading depolarization in the brain . . . migraine really is a neuronal dysfunction as well as a vascular dysfunction associated with allodynia,” Tobis said.
Numerous observational studies have demonstrated an association between PFO closure and migraine reduction (Figure 2). The MIST trial was established to address this relationship.
Although the primary endpoint of complete cessation of migraine was not achieved, the positive secondary endpoints (reduction in migraine frequency/severity) raise some interesting points for future consideration.
The role that residual shunts play in persistent migraines is important to examine. This examination will help determine whether migraines are caused, at least in part, by passage of chemicals through the PFO, Tobis said.