Over the past several years, device manufacturers have introduced a number of PFO closure devices in Europe, but conducting randomized trials to gain US market approval has proven to be a much more difficult endeavor. Companies have experienced numerous delays and setbacks in both their stroke and migraine programs. The good news: setbacks for some could also boost randomized migraine studies still ongoing by other competitors in this field.

These are tough times for companies developing PFO closure devices. Various energy-based approaches have hit the rocks, and clinical trial enrollment difficulties have derailed others. Coherex Medical hopes for better results with technology that it describes as safe, user-friendly, and more effective than competing technologies. The company's FlatStent PFO closure system combines a self-expanding stent with tissue growth materials, and a design that provides multiple means to close the PFO and thus boost the chances for long-term success.

Medical device investors who have avoided heart failure, because of the long and uncertain development course of ventricular assist devices, should take another look. The minimally invasive revolution in heart failure, to some extent a logical extension of interventional cardiology's migration into other areas of structural heart disease like heart valves and PFOs, is providing new device opportunities, which have the potential to get to market sooner and at the same address an even larger patient population than heart failure devices that came before.