A study comparing Abbott’s (NYSE:ABT) MitraClip and open heart surgery for mitral valve repair showed that the device was less effective but safer than surgery.
Analysis of one-year and some two-year results of the Everest II study, published today in the New England Journal of Medicine to coincide with the 60th annual meeting of the scientific meeting of the American College of Cardiology in New Orleans, analyzed the data based on the initial treatment intent for the subjects, instead of the treatment they eventually got.
The Abbott device is designed to slip over the valve leaflets of patients with aortic valve stenosis, restoring some of the valve’s ability to keep blood for flowing back into the heart.
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Of the nearly 280 patients in the study, 73 percent of those treated with open heart surgery survived the procedure, didn’t need follow-up repair of the valve and showed lower rates of mitral valve regurgitation. Only 55 percent of the MitraClip cohort met those criteria, according to the study.
But after 30 days, only 15 percent of the MitraClip subjects experience a major adverse event, versus 48 percent for the surgical interventions, and the rates of major events excluding transfusions and for transfusions requiring two units of blood or more were much lower for patients treated with the Abbott device.
Other two-year data from the study, comparing the device plus follow-up surgery if it failed with surgery alone, showed that no significant difference after both one and two years, according to Dr. Ted Feldman, lead author and associate head of cardiology at Rush-Presbyterian-St. Luke’s Medical Center in Chicago. Feldman reported receiving grants to serve as an adviser or consultant for Abbott and Edwards Lifesciences (NYSE:EW).
Based on the intent-to-treat analysis, "the benefit of surgery over the clip was entirely driven by patients in the clip group who needed subsequent surgery. We have shown that at one year, 80 percent of the clip patients do not need surgery; at two years, this is practically the same, at 78 percent," he told the heartwire blog (paid). "Almost all patients who had the clip but then needed surgery had surgery within six months. So if a patient gets the clip and gets to six months, they do fine. The odds of avoiding surgery are much better with the percutaneous procedure."
But Dr. Robert Bonow of Northwestern University said Abbott’s MitraClip might be better for older patients who are too sick to undergo open heart procedures.
"This device does not stop regurgitation as well as surgery, and there is a creep phenomenon, with severe regurgitation rates rising as follow-up increases in the percutaneous group," he told the blog. "With longer-term follow-up, these patients may need surgery."
And several of the patients in the study who needed surgery after the placement of the clip wound up having an artificial replacement valve implanted, Bonow noted, adding that the trial subjects were selected for their suitability for mitral repair.
"My concern here is that perhaps the clip could have damaged the valve so that it is no longer suitable for repair and has to be replaced," he told the blog. "You have to remember that only one in seven patients were candidates for Everest in the beginning. Then the clip is not successful in almost one-quarter of them. And half of these get replacement rather than repair when they undergo subsequent surgery."
Abbott hailed the study as evidence that the MitraClip might be ideal for elderly or frail patients, according to prepared remarks from Dr. Donal Glower, a co-author of the NEJM report and, along with Feldman, co-principal investigator for the Everest II trial.
ABT shares were up 1.8 percent to $50.24 by mid-day, as the company surfed a wave of good news out of the ACC conference for its Xience V drug-eluting stent.