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Catheter-Based Mitral Valve Repair Compares with Open Heart Surgery at One Year

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Abbott Vascular

MitraClip® repairing mitral
valve without surgery

April 10, 2010 -- Atlanta, GA -- One of the more striking recent developments in the surgery vs. angioplasty story was presented at last month's American College of Cardiology 59th Annual Scientific Sessions in Atlanta: The EVEREST II trial one year results showed that a non-surgical approach to repairing a leaky mitral valve was successful and compared well with open heart surgery, which is currently the gold standard of treatment for mitral regurgitation (MR). Using a device delivered by catheter, snaked through the femoral (groin) artery like coronary angioplasty balloons and stents, cardiologists were able to repair mitral valves successfully -- without surgery.

The device, originally developed by Menlo Park-based eValve, Inc., is called the MitraClip® and was cleared for use in Europe two years ago. In November 2009, Abbott acquired eValve and the company is hoping for a decision on FDA approval of the MitraClip sometime next year. Results of the EVEREST II trial have been submitted to support that process.

Mitral Regurgitation (MR)
Mitral regurgitation is the most common type of heart valve insufficiency and occurs when the leaflets of the mitral valve do not close completely, causing blood to flow backwards and leak into the left atrium of the heart during the cardiac cycle. To maintain an adequate forward flow of blood throughout the body, the heart compensates by increasing the size of the left ventricle (main pumping chamber of the heart) to accommodate the increase in the volume of blood it is pumping. When this defect become significant, the condition becomes debilitating and the heart's function deteriorates, leading to irregular heartbeat, heart failure, stroke, heart attack or death. Mitral regurgitation affects millions of people in the United States and Europe and is currently managed with drugs or open heart surgery, depending on an individual patient's severity of MR and risk factors. Some estimates place the number of U.S. patients with significant MR at 250,000 -- yet only 20% opt for repair, possibly because the operation involves major open heart surgery.

EVEREST II One Year Results
The EVEREST (Endovascular Valve Edge-to-Edge Repair Study) II trial enrolled 279 patients and is the first randomized clinical trial to compare a percutaneously delivered device directly with open surgery for repair of the mitral valve. The measures were safety at 30 days and efficacy at one-year.

At 30 days, the safety superiority over open surgery was striking: 57% of the surgical patients experienced a Major Adverse Event (defined as death, major stroke, reoperating, urgent or emergency surgery, heart attack, kidney failure, blood transfusions, etc.) compared to only 9.6% of the MitraClip patients. Many of these events were related to the need for blood transfusions, a point brought up by surgeons at the presentation. However, as Dr. Ted Feldman of Evanston Hospital in Illinois noted, there were no deaths, strokes or emergency surgeries in the MitraClip cohort.

The one-year efficacy results favored the surgical group of patients but, as defined by the trial endpoints, the MitraClip was still "non-inferior". The clinical success rate (freedom from death, surgery for valve dysfunction or moderate to severe MR -- a grading of more than 2+) was 87.8% for the surgical group and 72.4% for the clip patients. Although surgeons stated that they would not be comfortable if their surgical procedures resulted in an MR grade of 2+ -- considered acceptable for the endpoint in EVEREST II -- Dr. Feldman once again stated that patients in the trial reported a significant increase in their quality of life -- he commented:

"The most striking thing in our experience is the remarkable clinical response. I've had patients who literally could not walk across the road without getting shortness of breath and who go home after this procedure and, in less than a week, are doing water aerobics."

    Dr. Ted Feldman
Dr. Ted Feldman
Evanston Hospital

What This May Mean for Patients
Although still not an approved device in the U.S., and perhaps not as effective as open surgery, the potential usefulness of the MitraClip is significant. For example, many patients suffering from MR may be too ill or elderly to be able to withstand the rigors of open heart surgery. So certainly for this population, the minimally invasive nature of this catheter-based procedure may offer relief from the debilitating effects of mitral regurgitation -- and may slow down the onset of heart failure.

One point that was debated at the presentation was the issue of being able to do future surgical repair on the mitral valve if, after a number of years, the clip did not provide the necessary relief. Dr. Craig Smith of Columbia University, in comments to, stated that he had done such a procedure a few years ago and found the clip and surrounding tissue to be clogged and scarred and not viable for surgical repair. Whether this proves to be a problem for other cases is something only "time will tell", he stated.

The MitraClip, along with other catheter-based valve repair and replacement devices, such as the CoreValve from Medtronic and the Sapien from Edwards, represents the first wave of minimally invasive structural heart interventions that ultimately may impact the field of open heart surgery, much as the balloon and stent affected bypass graft surgery.

Reported by Burt Cohen, April 10, 2010