Eight-year study confirms PFO closure was superior to medical therapy alone in reducing risk of recurrent stroke in prespecified per-protocol and as-treated cohorts
ST. PAUL, Minn. – March 20, 2013 – St. Jude Medical, Inc. (NYSE:STJ), a global medical device company, today announced publication of results from its landmark RESPECT trial 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 (a stroke from an unknown cause) in patients with a common heart defect called 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.
Normal in a developing fetus, the foramen ovale allows oxygenated blood from the placenta to bypass the lungs. This small, flap-like opening typically closes shortly after birth. When this flap remains open, or patent, it is referred to as a PFO. A PFO can potentially allow dangerous clots to pass from the right side of the heart to the left, travel up to the brain and cause a stroke. Studies show that nearly half of all people who suffer a cryptogenic stroke also have a PFO.
“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.”
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. The average age of the patients in this trial was 46-years old. The trial was a prospective, controlled, randomized (1:1) study in which patients were randomly assigned to either the device group or the medical group. The primary efficacy endpoint was defined as the composite rate of recurrent nonfatal stroke, fatal ischemic stroke or death after randomization. Enrollment was stopped once 25 events occurred, all of which were non-fatal recurrent stroke, as measured across all patients in the study.
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.
Analyses were conducted on the intent-to-treat population, which included all patients according to the group to which they were randomly assigned, though some patients in the device group did not receive the randomized treatment. 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. Using the same intent-to-treat cohort in a time-to-event analysis demonstrated a risk reduction of greater than 50 percent, which trended towards statistical superiority with a p-value of 0.08.
The study protocol also prespecified that if dropout rates differed significantly between the medication and device groups that analyses of two additional cohorts would be evaluated. These included:
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Last updated on: 25/03/2013
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