NEJM Study Publication Gives St.Jude Amplatzer PFO Boost

In short

In February St. Jude Medical, Inc. was trumpeting results from its RESPECT stud, claiming that the Amplatzer PFO occluder device reduced recurrence of strokes. Now the company has followed this data up by drawing our attention to the publication of results in The New England Journal of Medicine.

The study results show that device closure using the AMPLATZER™ PFO Occluder is superior to antiplatelet medications or warfarin in preventing recurrent cryptogenic stroke  in patients with a patent foramen ovale (PFO), as measured in the prespecified per-protocol and as-treated patient cohorts of the trial. Patients in the study had a 51 to 73 percent risk reduction in recurrent strokes when evaluated across prespecified measures.

Background

Up to 40 percent of ischemic strokes are classified as cryptogenic, which means the cause of the stroke is unknown. A PFO has been fingered as a potential cause of cryptogenic stroke as it can allow dangerous clots to pass from the right side of the heart to the left and travel up to the brain. Studies show that nearly half of all people who suffer a cryptogenic stroke also have a PFO.

Conducted over the course of eight years at 69 medical centers in the U.S. and Canada, the RESPECT study followed 980 participants who had suffered a cryptogenic stroke that was confirmed by stroke neurologists using routine imaging technologies.

Patients in the device group underwent a procedure in which their PFO was closed with the Amplatzer PFO Occluder followed by six months of medication therapy. In the medical group, four standard-of-care medical therapy regimens were used throughout the study: aspirin, warfarin, clopidogrel and aspirin combined with extended release dipyridamole.

A difference in the dropout rate between the medical therapy group and the device group challenged the validity of the primary intent-to-treat raw count analysis, which did not meet statistical significance.

The full details of the study can obviously be found in the NEJM or in the St.Jude press release, here. In short though the results demonstrated a risk reduction of greater than 50 percent, which trended towards statistical superiority with a p-value of 0.08 when using the device.

Device closure was superior to medications alone with a low rate of associated risks. There were no statistically significant differences in the incidence of any serious adverse event between the two groups.

The company will be relieved to see this study published because other clinical evidence has not all been quite as supportive. Studies have variously concluded that Amplatzer patients suffered the same stroke rates as those who used existing treatments. Indeed two recent studies found that the device didn’t significantly reduce the risk of a second stroke compared to regular drug treatments.

Physician comments

“The results of this landmark study are clinically important as we continue to search for solutions for young and middle-aged patients with a long-life expectancy, who are at risk of having a second stroke. The RESPECT trial data shows device closure with the AMPLATZER PFO Occluder, in carefully selected patients, is quite safe, effective in closing the PFO, and lowers the risk of recurrent stroke in two of the three patient cohorts,” said Dr. John D. Carroll, director of the Cardiac and Vascular Center and Interventional Cardiology at the University of Colorado Hospital and lead author of the journal article. “The reduction in stroke achieved in the PFO-closure group exceeds that of several well-established pharmacologic treatments for the prevention of secondary strokes.”

Company comments

“The analysis of the data from patients in the per-protocol group and the as-treated group provide compelling evidence that PFO closure with the AMPLATZER PFO Occluder is superior to medical management from both clinical and statistical perspectives,” said Frank J. Callaghan, president of the St. Jude Medical Cardiovascular and Ablation Technologies Division. “The totality of evidence from this study, including the strong performance and safety profile of the device, demonstrates the compelling clinical benefits of closure versus medical management in reducing the likelihood of recurrent stroke in this patient population.”

Source: St.Jude Medical, Inc.