ACC: MitraClip system may present alternative for non-surgical patients
MitraClip system.
Image Source: Evalve/Abbott
ATLANTAThe MitraClip system, a catheter-mounted device that acts like a clothespin to clip together the flaps of a leaky mitral valve, is a safe and effective alternative to open-heart surgery in selected patients with mitral regurgitation, according to the EVEREST II trial presented today at the American College of Cardiology’s (ACC) 59th annual scientific session.

The Endovascular Valve Edge-to-Edge Repair Study (EVEREST II) involved patients with significant regurgitation through the mitral valve, which keeps blood from flowing back to the left atrium from the left ventricle.

More than 250,000 people in the U.S. are diagnosed with mitral regurgitation annually.

The EVEREST II study was designed to evaluate the safety and effectiveness of the MitraClip procedure in comparison with the gold standard treatment, mitral valve surgery. However, lead author Ted Feldman, MD, director of the cardiac catheterization laboratory for NorthShore University Health System in Evanston, Ill., reported that only about 20 percent of patients with significant mitral regurgitation undergo mitral surgery.

For the study, researchers from 37 North American medical centers recruited 279 patients who fit the ACC/American Heart Association guidelines for mitral valve surgery (moderate-to-severe [Grade 3+] or severe [Grade 4+] mitral regurgitation).

Patients were randomly assigned in a two-to-one ratio for treatment with the MitraClip device (184 patients) or mitral valve repair or replacement surgery (95 patients).

The minimally invasive MitraClip procedure was successful in 137 patients, and of these, 136 were available for inclusion in the data analysis at 30 days; 79 surgical patients were available for 30-day follow-up.

The comparative safety of the two procedures was gauged by major adverse clinical events (MACE) at 30 days. The 30-day MACE rate in the MitraClip group was 9.6 percent compared with 57 percent in the surgery group.

In his response to the EVEREST presentation, J. Scott Millikan, MD, from the Billings Clinic in Billings, Mont., complimented the collaborative nature of the study between surgeons and invasive cardiologists in the development of this “new and exciting technology.”

The difference between the two groups represented a “highly significant finding” of superior safety with the MitraClip, according to Feldman, who also added that surgery is still an option after the procedure occurs.

However, Milikan said he was “disappointed” that only seven patients at each site underwent randomization and treatment, leading him to question the screening process and call the study’s patient population “very highly selective.” Feldman acknowledged that the patient group is “highly selective, as selection is truly critical in surgical therapy.”

Milikan also questioned whether blood transfusions should be weighed against stroke and death as adverse event.
Finally, he said his greatest concern is EVEREST II’s definition of success. “There are very few surgeons who believe they were successful with two plus mitral regurgitation after attempted valve repair. There are fewer cardiologists who would continue to send their patients to surgery with these results. At the end of the trial period, only 21 percent of the patients who initially went to the cath lab had a successful period, with two to four plus mitral regurgitation at one year. I am not sure that these results are that encouraging.”

Feldman noted that outside of this pivotal trial, there is a “large group of patients that could not undergo surgery, with a mean STS risk score of 14 and many of whom have two plus mitral regurgitation and all of whom have diminished ventricular volumes at one year, suggesting that whatever the residual in this group, the threshold for adequate therapy may be quite reasonable. Also, balanced against the risk of these patients, this is particularly important.”

As a result, Feldman suggested that those patients who are at higher risk for surgery—the elderly and the frail—will be “very well suited for this therapy. And, as this is the beginning of our trialing with these devices, we will improve our patient selection process over time. ”
Feldman also reported the comparative effectiveness of the two procedures was gauged at 12 months by freedom from a combination of death, new surgery for mitral valve dysfunction or more than mild mitral regurgitation. Clinical success was achieved at 12 months by 72.4 percent of patients treated with the MitraClip and 87.8 percent of those treated with surgery, a highly significant finding of the noninferiority of the MitraClip.

At 30 days, quality of life was significantly improved in the MitraClip group, but was worse in the surgery group. By 12 months, both groups reported significant improvement in quality of life.
“As clinicians, we have seen our patients transformed from highly symptomatic to highly functional with a catheter procedure—and without a long hospital stay or a long recovery period,” said Feldman.

Milikan acknowledged that this device will probably join the armarium of techniques for this patient population.

The EVEREST II study was funded by Evalve, which also provides research funding to NorthShore. Feldman is a consultant to Abbott, which recently acquired Evalve.