New Insights Into MitraClip Performance in Both Functional and Degenerative MR Subtypes, as Use Expands
CHICAGO, IL—An analysis of patients treated with the MitraClip since its US approval in 2013 suggests that certain subtypes of both degenerative and functional mitral regurgitation (MR) may be particularly well suited to the procedure.
Importantly, say the researchers, improvements in MR grade were seen in both degenerative and functional disease, offering an early hint that the MitraClip (Abbott Vascular), currently approved for use in degenerative MR only, may also have a role in certain patients with functional MR.
Atif Qasim, MD (University of California, San Francisco), presented the results last week at the American College of Cardiology 2016 Scientific Sessions.
The EVEREST II REALISM registry includes data on real-world use of MitraClip since its approval in the United States in 2013 for the treatment of significant symptomatic degenerative MR in patients at prohibitive risk for surgery. Additional trials still underway, including the US COAPT trial, are examining whether the device is also beneficial in functional/secondary MR, but the wait for these results clearly hasn’t stopped physicians from treating patients with this type of mitral valve disease.
“Worldwide, especially in Europe, [the MitraClip] remains predominantly used in functional MR,” Qasim noted. Even in the United States, he said, operators “have been pushing the envelope in terms of what kinds of patients can receive the MitraClip.”
For their study, Qasim and colleagues reviewed echocardiographic results at the time of hospital discharge (or at 30 days, if no discharge echo was performed) for 840 patients treated with the device in the years since regulatory approval. Of note, almost two-thirds of the patients who received MitraClip (n = 520) had functional mitral regurgitation. Improvement in MR grade was then reviewed according to mitral valve pathology or regurgitation etiology.
They report that the majority of degenerative MR patients had posterior leaflet prolapse (n = 190), followed by anterior leaflet (n = 95). Just 35 patients had bileaflet prolapse. In the functional MR group, 240 patients had disease that was ischemic in origin, while 280 had nonischemic MR. Regardless of MR type, most patients were had class III or IV heart failure at the time of treatment. At baseline, approximately 90% of degenerative MR patients had class 3+ mitral regurgitation or higher; that rate was slightly lower, at approximately 80%, in the functional MR group.
Following treatment, 92% of patients with anterior leaflet degenerative MR had improved by at least one MR grade, a number that reached 93.5% in the posterior leaflet prolapse group and fell to 82.9% in patients with bileaflet prolapse. Improvement in MR in the degenerative group was particularly marked among patients with posterior leaflet prolapse, with 48 out of 190 patients experiencing improvements of three or more MR grades postprocedure.
In the functional MR group, improvement of at least one MR grade was seen in roughly the same proportion of patients with ischemic MR (82.6% of patients) as in patients with nonischemic MR (88.1%). Improvements were also similar regardless of whether patients had single leaflet or bileaflet MR: 67 patients and 68 patients, respectively.
“It’s interesting that the early procedural success rates are fairly good. And it doesn’t seem to matter whether you have ischemic or nonischemic MR, or whether you have bileaflet or single leaflet tethering, the success rates are actually still pretty high,” Qasim told TCTMD. “I think part of that is a testament to the fact that the operators are growing very experienced and they’ve selected these patients very carefully.”
As the numbers suggest, he continued, “we're now starting to push the boundaries, especially in individuals who are very sick, who can’t have surgery. I think that’s where this data will be interesting. Even in the degenerative group the indications are expanding, and even though it’s still degenerative MR, there are actually a lot of types of degenerative MR, and there are some individuals who probably before we wouldn’t even touch with a MitraClip but now we’re actually thinking about.”
What the current data suggest is that improvements in mitral grade after MitraClip procedures are roughly similar for degenerative anterior and posterior leaflet prolapse, but were somewhat lower when both leaflets were affected.
In the functional group, by contrast, “procedural success rates were high overall and similar regardless of etiology,” Qasim said.
“I’m excited to see what happens with the COAPT study,” Qasim continued. “For a lot of us clinicians, that’s really the group where we struggle the most because a lot of them can’t have surgery, the data for surgery is not that clear, and those individuals tend to be sicker [whereas] those with degenerative MR tend to be younger and are usually much better candidates for surgery. So I think functional MR is the population where this device can hopefully have a big impact.”
Qasim predicted that COAPT still needed “40 or 50” more patients before it will have reached its target enrollment. In late February, Ted Feldman, MD (NorthShore University Health System, Evanston, IL), coprincipal investigator on EVEREST II, estimated the number still needed for COAPT to complete enrollment to be 80.
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Qasim A, Kar S, Weissman N, et al. Everest II REALISM: Early success rates of MitraClip placement by etiology of regurgitation and mitral valve morphology. Presented at: American College Cardiology 2016 Scientific Sessions. April 4, 2016. Chicago, IL.
- Qasim reports research grants from Abbott Vascular.