NEW YORK (Reuters Health) – Following transcatheter closure of a patent foramen ovale (PFO), migraine relief may occur despite residual right-to-left shunt, researchers report in the October 1st issue of the American Journal of Cardiology.
The team, based at the Swedish Medical Center in Seattle, also found that patients with migraine with aura were more likely to experience fewer headaches after the procedure than those who did not normally experience auras.
The mechanism underlying the association between migraine and a PFO likely involves the cortical hypersensitivity associated with migraine headaches, lead author Dr. Jill T. Jesurum explained. “A large right-to-left shunt permits a greater volume of vasoactive chemicals and microaggregates, such as activated platelets, to cross the PFO and trigger migraine,” she told Reuters Health.”
It was unclear if complete elimination of the right-to-left shunt is required to mitigate this effect. To explore this issue, Dr. Jesurum and colleagues studied 246 patients who underwent transcatheter PFO closure for the prevention of recurrent cerebrovascular events, one third of whom suffered from recurrent migraine.
Final PFO closure was assessed by transcranial Doppler ultrasonography among 67 patients who had migraine at baseline. Closure was classified as complete in 44 patients and incomplete in 23.
There was no significant difference in the proportion of patients with complete vs incomplete closure who experienced a reduction of at least 50% in migraine frequency (77% vs 83%), or in the final migraine frequency.
As to why only partial PFO closure would still be effective, Dr. Jesurum surmised that “a reduction of shunt and therefore transmission of vasoactive chemicals and microaggregates below a particular threshold of cortical hypersensitivity may result in a reduction in migraine symptoms.”
Migraineurs with aura were more than four times more likely than migraineurs without aura to experience relief after PFO closure, the authors report.
“This is very important information for investigators designing PFO closure trials for migraine indication and for patients considering PFO closure for migraine treatment,” Dr. Jesurum said.
“I don’t believe we have the evidence to support PFO closure for all people with migraine,” she added. “There may be a subpopulation of migraineurs for whom there is some potential causal mechanism between PFO and migraine and who may benefit from PFO closure, but the mechanism has yet to be determined.” A larger, prospective study will be needed before any definitive conclusions can be made on the effectiveness of PFO closure in reducing migraines.
“Our investigative team is now focusing on the role of platelets and platelet activation in migraine,” the researcher noted. “Migraineurs have a higher incidence of venous thromboembolism, which suggests underlying platelet hyperactivation. In the near future, we will be reporting on the effects of aspirin on platelet activity in migraineurs and if chronic aspirin therapy may have a role in migraine prevention.”
Reference:
Am J Cardiol 2008;102:916-920.
