No Advantages, More Surgery, With MitraClip at Four Years: EVEREST II

May 07, 2013

BOSTON, MA — Four-year follow-up of the Endovascular Valve Edge-to-Edge Repair Study II (EVEREST II) show no differences in the primary end point between the MitraClip (Abbott) procedure and surgery and significantly more follow-up surgeries for residual mitral regurgitation (MR) in the clip group[1].

At four years, surgery for mitral-valve dysfunction was needed for one out of every four patients treated with the MitraClip compared with just 5.5% of patients who underwent surgery. The rate of the primary effectiveness end point, a composite that includes freedom from death, surgery, or 3+ or 4+ MR, was 39.8% in the percutaneous-repair arm and 53.4% in the surgical group, a difference that was not statistically significant (p=0.070).

Dr Laura Mauri (Brigham and Women's Hospital, Boston, MA), the lead author of the four-year EVEREST IIreport, which is published online May 6, 2013 in the Journal of the American College of Cardiology, said that while the comparison of the procedures in a surgical population favors surgery, the "trial is important in that it provides useful information about the long-term durability of the device."

She explained that treatment with the MitraClip was associated with mortality rates similar to surgery at one year, but the degree of MR reduction was less with percutaneous repair. At one year, approximately 20% of MitraClip patients required mitral-valve surgery to treat moderate or severe MR compared with 2.2% of patients treated with surgery.

"Now that we have four years of follow-up, we are reassured to see that in both arms of the study, MitraClip and surgery, among those with a good initial result, durability of both procedures is good," Mauri told heartwire . "Few patients in either arm required additional procedures, and the degree of MR reduction and left ventricular volumes and clinical measures like New York Heart Association class remained stable. This suggests that those patients who get a good acute procedural result from the MitraClip have stable results over the next three years."

Commenting on the results for heartwire , cardiovascular surgeon Dr Steven Bolling (University of Michigan, Ann Arbor) said the four-year results are what would be expected given the one-, two-, and three-year data and that it shows the percutaneous approach is not as good as surgery in patients eligible for surgical repair. However, he criticized the trial design, noting that EVEREST II allowed the interventionalists to complete the procedure if the MR was reduced to 2+. In contrast, in the hands of a surgeon, a procedure is considered successful if there is no MR.

"In those patients, to leave them with two plus, they're going to do poorly and then 25% at four years are going to need another operation anyway," said Bolling. "And in some of these patients you're not going to be able to do the repair. That's a disaster."

The EVEREST II Study

The EVEREST II study included 279 patients with significant MR (3+ to 4+) randomized 2:1 to the MitraClip procedure or to surgical repair or replacement at the surgeon's discretion. To be entered in the trial, patients had to be symptomatic or, if asymptomatic, to have documented left ventricular dysfunction.

At one year, as reported previously by heartwire , treatment of MR with the MitraClip showed superior safety, but less reduction in MR. At four years, there was no significant difference in the primary composite end point, as noted. There was also no significant difference with regard to mortality alone or 3+ or 4+ MR, but the need for mitral-valve surgery at four years was significantly higher among patients who received the MitraClip.

Effectiveness End Point and Components

End point Percutaneous repair (%) Surgical repair (%) p
Freedom from death, mitral-valve surgery, or MR 3+ or 4+ 39.8 53.4 0.70
Death 17.4 17.8 0.914
Mitral-valve surgery or reoperation 24.8 5.5 <0.001
MR 3+ or 4+ 21.7 24.7 0.745

"It has also been reassuring to see that left ventricular dimensions have remained stable for these patients," Mauri said. "Still, the device is currently best suited to patients who are too high risk for surgery, who might not otherwise be able to safely undergo correction of MR but might benefit from reduction in its severity."

Despite his criticisms, Bolling called EVEREST II an "exploratory trial," one in which investigators were uncertain which patients would receive the most benefit from the less invasive MitraClip procedure. As such, the investigators included degenerative- and functional-MR patients. In Europe, the device is used primarily in high-risk patients with functional mitral-valve disease and not in patients with degenerative valvular leaflet disease. The COAPT and the RESHAPE-HF studies are both testing the MitraClip in this high-risk functional-MR population, he said.

Bolling said that while the results are durable, they are still "bad results." In hindsight, the investigators might have selected to leave only MR 1+ following the percutaneous procedure because any MR left behind has an adverse effect on clinical outcomes, he told heartwire . He does not believe the MitraClip is a good option for patients who are eligible for surgery.

"In a patient where surgical risk is very high, it may make sense to avoid the up-front risk if a good result can be achieved with a less invasive procedure," added Mauri. "On the other hand, in good surgical candidates, where more complete treatment can be achieved with surgery with minimal risk, up-front surgery makes more sense."

In Europe, the MitraClip device has CE Mark approval, but it is not yet approved in the US. In March, a Food and Drug Administration advisory committee voted narrowly voted to have the device green-lighted for US patients when it stated the efficacy of the device exceeded the risks. The proposed indication for the MitraClip is for symptomatic MR (>3+) patients deemed too high risk for open mitral-valve surgery by a cardiac surgeon and in whom existing comorbidities would not preclude the expected benefit from the correction of MR.

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