PARIS, France—Mitral valve repair with a percutaneously delivered clip treats mitral regurgitation (MR) effectively whether the condition is degenerative or functional in nature, according to data presented May 25 at a late breaking trial session at EuroPCR 2010.
The results, which expand on data presented March 14, 2010, in Atlanta, GA, at the American College of Cardiology Scientific Session/i2 Summit, also show that the benefits of the MitraClip system (Abbott Vascular, Abbott Park, IL) are durable compared with open surgery out to 2 years.
The MitraClip system involves a clip that is inserted into the mitral valve via percutaneous femoral venous transseptal access. The device is then passed across the mitral leaflets and used to grasp them in order to create a double orifice.
For the prospective EVEREST (Endovascular Valve Edge-to-Edge REpair STudy) II trial, researchers led by Ted Feldman, MD, of Evanston Hospital (Evanston, IL), randomized 279 patients with significant MR (3+ to 4+) in a 2 to 1 ratio to receive treatment with the clip device (n = 184) or surgical repair/replacement (n = 95). There were no baseline differences between the 2 groups with 1 exception, a higher rate of congestive heart failure in the device group (90.8% vs. 77.9%; P < 0.01).
Initial ACC/i2 Results
In the results released at the ACC/i2 Summit in March, the device was equivalent to surgery in terms of the efficacy endpoint of 1-year freedom from death, mitral surgery, or MR > 2+ (72.4% with the clip device vs. 87.8% with surgery; P for noninferiority = 0.0012). In addition, the clip was superior to surgery with regard to 30-day major adverse events (9.6% vs. 57.0%; P < 0.001). The adverse event composite, though, included blood transfusions, which some regarded as inappropriate. Over half of the surgery group required transfusions of more than 2 units (53%) compared with only 8.8% of the device group.
New Composite, Similar Results
For the new analysis, results in the device group were broken down by MR etiology, comparing patients with degenerative (n = 135) and functional MR (n = 49).
“This is an important analysis because the double orifice surgical repair was initially developed entirely in patients with degenerative MR, and when we started with the MitraClip experience in 2003, it was not clear that functional MR patients would do well with this therapy,” Dr. Feldman explained.
In the study, functional MR patients had a much higher prevalence of CAD and history of CABG. For the composite of major adverse events, transfusions were replaced as an endpoint by major bleeding, which was defined according to the Society of Thoracic Surgeons database. Despite the modification, the composite—which also included death, major stroke, re-operation, MI, and several other complications—remained low and equivalent in both categories of MR patients (table 1).
Table 1. Primary Safety Endpoint
|
Degenerative MR Patients
(n = 135)
|
Functional MR Patients
(n = 49)
|
Surgery Patients
(n = 94)
|
30-Day Major Adverse Events
|
8.1%
|
8.2%
|
42.6%
|
In terms of MR reduction, 81.5% of the device patients were ≤ 2+ at 12 months, compared with 97.0% of the surgery patients. Broken down by etiology, 82.8% of patients with degenerative MR and 78.1% of those with functional MR were ≤ 2+ at 12 months
Meanwhile, left ventricular end diastolic and end systolic volumes were significantly reduced between baseline and 12 months in both degenerative and functional MR patients treated with the clip device. There was only a difference in systolic left ventricular internal diameter, which was lower at 12 months in the functional MR group (P = 0.01), but not in the degenerative MR group (P = 0.378).
In terms of NYHA class, results were remarkably similar regardless of MR type at 12 months, with 97.8% of degenerative MR patients and 96.7% of functional MR patients in class I/II (P < 0.0001 vs. baseline for both comparisons).
With regard to quality of life, both the degenerative and functional MR groups significantly improved in terms of mental functioning at 12 months vs. baseline. However, in terms of physical functioning, the degenerative MR patients improved by 12 months (P < 0.0001), while the functional MR patients did not (P = 0.4).
Two-Year Findings Continue to Be Positive
While 2-year follow-up is still incomplete, Dr. Feldman presented results showing that on intention-to-treat analysis, just under 80% of the device group remained free from re-operation at 2 years, compared with approximately 98% of the surgery group. Kaplan-Meier curves were roughly parallel after the first few months. Meanwhile, on per-protocol analysis, freedom from re-operation was almost identical at approximately 97% in both groups.
“When you look at patients who initially had a successful clip procedure, the 2-year Kaplan-Meier event curves are virtually superimposed,” Dr. Feldman said.
“Overall, compared to surgery, the MitraClip did meet safety and effectiveness endpoints,” he summarized. “The durability of the clip procedure is similar to surgery through 24 months. Clinical benefit has been demonstrated for both degenerative and functional MR patients following the clip procedure assessed by left ventricular function, functional class, and quality of life scores. I think this underscores our finding for the overall group, that for selected patients, the MitraClip is clearly a therapeutic option for patients with significant mitral regurgitation.”
Concern Over Annular Dilatation
Thierry Folliguet, MD, a cardiovascular surgeon from L'institut Mutualiste Montsouris (Paris, France), called the clip device “a very brilliant idea,” but pointed to Cleveland Clinic data showing that 20% to 30% of patients who had MR > 2+ after being treated with the device required re-operation. The reason, he noted, was annular dilatation.
“When you don’t do an annuloplasty, you have up to 30% of patients re-operated,” Dr. Folliguet said. “In selected patients, if they have central MR with no annular dilatation, this technique is probably sufficient and you don’t have to do an annuloplasty. I think this is clearly an advancement, but in order to improve it, you have to work on a device where you can also get some kind of remodeling of the annulus.”
Source:
Feldman T. EVEREST II randomized clinical trial update: Degenerative vs. functional MR 2-year outcomes. Presented: EuroPCR; May 25, 2010. Paris, France.
Disclosures:
- Dr. Feldman reports receiving research grants from and serving as a consultant to Abbott and Edwards.
- Dr. Folliguet reports no relevant conflicts of interest.
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