Although the MIST study fails to demonstrate the primary end point of cessation of migraine with aura following patent foramen ovale closure, it did show the percentage of patients achieving the secondary end point of 50 % reduction in headache days was comparable to conventional preventive drug treatments. Here discussant Eric Eeckhout (Lausanne, Switzerland) provides an overview of the results.
The MIST trial : new hope for a debilitating disease?
Despite the absence of evidence based information, percutaneous closure of a patent foramen ovale (PFO) is the most frequently performed non coronary cardiac intervention, commonly after cryptogenic stroke. The ongoing randomised trials for this potential indication suffer from slow recruitment and results will not be available soon.
The rationale for MIST was based on retrospective data showing the higher prevalence of PFO in patients with migraine (+aura) and the beneficial effect after device closure.
MIST is the first completed randomised PFO trial and its results have now partially been made available.
By definition MIST is a original - landmark trial. The strength of the trial further lays in aspects of its design and conclusions. The double-blind (sham intervention) aspect was essential to judge the magnitude of the placebo effect. MIST is the first scientific proof of the higher prevalence of PFO (±factor 6) in migraine with aura. The percentage of patients with a 50% reduction in headache days was significantly higher after closure and comparable to most migraine drugs but in more refractory patients.
The weakness of the trial relates to the following points : a. the ambitious primary end point in relation to the study sample, b. the unavailability till present of the closure rate, c. the short follow-up period and d. the relatively high incidence of serious adverse events. In particular, knowledge of the closure rate is essential as any form of residual shunting (at the level of the PFO or other) may have affected the trial results.
Practically, MIST strongly supports to pursue the ongoing trials. At present, PFO closure can not be recommended as a routine procedure for migraine patients. Patients with debilitating migraine who wish to have the PFO closed should be fully informed on the current knowledge and fully consent prior to intervention.
Slide presentation [Available]
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