One of the biggest topics of discussion amongst Migraineurs today is that of PFO, "the hole in the heart" that may contribute to Migraines. Migraineurs are asking their doctors to test them to see if they have this condition. Many of those who do want to have the hole repaired -- immediately. However, questions remain and the closure procedure is not yet being performed on the basis of Migraine disease because it has not yet been proven effective.

NMT Medical, Inc. has now initiated enrollment in its PFO/Migraine clinical study in the United States. The study, named MIST II (Migraine Intervention with STARFlex® Technology), will evaluate the safety and effectiveness of NMT's proprietary STARFlex® implant technology for the treatment and prevention of Migraine attacks in patients with a patent foramen ovale (PFO). The MIST II Clinical Trial has been specifically designed to investigate Migraine sufferers with a PFO and demonstrate if PFO closure can offer an effective treatment for this type of Migraine sufferer. MIST II is a prospective, randomized, multi-center, controlled study. The double-blinded trial is designed to randomize approximately 600 Migraine patients with a PFO to either PFO closure with NMT's STARFlex® technology or a control arm. More than 40 leading Migraine specialists and interventional cardiologists have committed to participate in MIST II. Enrollment is currently expected to be complete by the end of 2006. Follow-up with the patients will be over a one-year period.

Stewart Tepper, MD and Mark Reisman, MD are the co-principal investigators of the MIST II clinical trial. Dr. Tepper is Director of The New England Center for Headache in Stamford, Connecticut. Dr. Reisman is Director of Cardiovascular Research at Swedish Medical Center, Seattle, Washington.

PFO stands for patent foramen ovale. A PFO is a hole in the wall (septum) that divides the right and left atrium (chambers) of the heart. We all have a PFO during fetal development, but it usually closes before birth. The right side of the heart receives blood and pumps it to the lungs for oxygenation. The blood then goes through the left side of the heart to be pumped to the brain and other organs. A PFO can allow blood that hasn't been oxygenated by the lungs to get into the left side of the heart, thus being pumped to the brain and other organs. If this happens, the body doesn't get enough oxygen. It's also possible that blood clots can pass through the PFO and cause a stroke. PFO is diagnosed with a TEE (transesophageal echocardiogram), which is performed by passing an ultrasound probe down the esophagus, near the heart to get better results than the traditional echocardiogram, which is performed with a standard ultrasound wand outside the chest.

John E. Ahern, NMT's President and Chief Executive Officer, said,

"Medical researchers continue to associate the PFO defect with the potential for increased risk of Migraine headaches, recurrent stroke and transient ischemic attacks (TIA). NMT maintains its leadership in this emerging opportunity with five separate PFO-related trials currently underway. MIST II is the second PFO/Migraine trial initiated by NMT. This pivotal trial was approved by the FDA earlier in the fourth quarter. Prior to that, NMT was the first to receive approval for and to complete enrollment in a PFO/Migraine study (MIST) in the United Kingdom. MIST results are currently expected in late March or early April of 2006. In October, the Company also announced approval of MIST III, a study designed to expand data and follow-up on MIST Migraine patients. With its ongoing CLOSURE I trial, the Company was the first to receive approval for and enroll patients in an IDE study in the U.S. to evaluate the safety and efficacy of the STARFlex® closure technology to prevent a recurrent embolic stroke and/or TIA in patients with a PFO. In November 2005, the Company announced that it had completed enrollment in the BEST study (BioSTAR(TM) Evaluation STudy). The BioSTAR(TM) implant represents a new generation of biological closure technologies that NMT is developing and evaluating in order to promote a more natural, rapid and complete sealing of heart defects such as PFO... The enthusiastic response to the Company's Migraine trials suggests a large, unmet demand in the medical community. It is NMT's goal to be the first company to provide those Migraine patients with a PFO- related treatment option."

On the PFO/Migraine connection from the point of view of some Migraine specialists and researchers:

"The unresolved question is whether the association between PFO, migraine with aura and stroke is causal or coincidental. Firs one has to keep in mind that PFO is frequent (25-30%) as is migraine (10-12%). Secondly, PFO and migraine with aura could be inherited and transmitted simultaneously. Third, it is difficult to understand the causal relationship between migrainous stroke and PFO. This would mean in a particular case, that a patient suffers from deep vein thrombosis and experiences a paradoxical embolization at the same time when suffering from a migraine attack with aura. This scenario is highly unlikely....Migraine, particularly migraine with aura is associated with PFO. This association might be due to a shared genetic preponderance. A causal link is unlikely. Despite some reports from retrospective studies of improvement of migraine after PFO closure, this procedure should not be performed for the prevention of migraine. None of the reports on improvement of migraine after PFO closure had a control group."

That last statement, "None of the reports on improvement of migraine after PFO closure had a control group," is crucial. Double blind trials where there one group receives the treatment and another receives a placebo are generally considered to produce most objective and accepted data. Addressing the need for this type of clinical data is the purpose of the MIST and MIST II trials.

For more information or to apply to participate in MIST II, visit the MIST II Web site.

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Resources:

Press Release. "NMT Medical Initiates Enrollment in MIST II Migraine Study in the United States. Clinical Trial will Evaluate the PFO/Migraine Connection." Boston. January 2006.

The MIST II Clinical Trial Web site.

Diener, Hans-Christoph; Weimar, Christian; Katsavara, Zaza. "Patent foramen ovale, migraine and stroke." Presentation to the 47th Annual Scientific Meeting of the American Headache Society. Philadelphia. June, 2005.

Published February 12, 2006