Mitral Regurgitation Promising, Needs Further Validation
In preliminary data from 92 patients in the EVEREST II trial, 95% of patients were free from adverse events at 30 days.
The field of percutaneous mitral valve therapy has made significant advances to address the challenges that beleaguered first-generation devices, according to Ted E. Feldman, MD, of Evanston Northwestern Healthcare, Evanston, Ill.
The total number of patients treated is in the low hundreds, but this number is increasing fairly rapidly, he said in a plenary session Tuesday. There are four approaches to mitral repair: coronary sinus annuloplasty, direct annuloplasty, leaflet repair and chamber and annular remodeling.
Coronary sinus annuloplasty
In a 36-patient study of the Evalve System (Evalve Inc.), 30 patients (83.3%) achieved the trial’s acute success endpoint, Feldman said. Four patients (11.1%) were discharged without implant, and two patients (5.5%) had delayed tamponade on day 1 and day 6, respectively, prior to discharge. In total, 28 of 32 patients (87.5%) were event-free at 30 days.
In those patients who received therapy, researchers observed one death, two tamponades and one myocardial infarction. The trial will continue to enroll up to 60 patients.
The fundamental concerns about coronary sinus annuloplasty are twofold, according to Feldman. The coronary sinus is typically between 5 mm and 10 mm away from the true mitral annulus, and when the implant device crosses the circumflex it is likely to impinge on the circumflex. Direct annuloplasty devices are being developed to address these limitations.
Direct annuloplasty
Researchers recently reported seven-year data of suture annuloplasty patients. Aybek et al reported in the Journal of Thoracic and Cardiovascular Surgery (2006;131:99-106) that at 77 months, 82% of patients had no significant recurrent mitral regurgitation. Additionally, 95% of patients were spared from undergoing another operation, and 87% of patients were free from mortality.
“These were excellent results,” Feldman said. “This is a technique that is very simple, but works.”
Leaflet repair
Similar to suture angioplasty, the direct leaflet approach uses clips on the microleaflets to approximate a suture. The clips create a double-orifice mitral valve, he said.
“It’s a percutaneously delivered clip that recapitulates the surgical result,” Feldman said. “A recent 12-year follow-up by Maisano et al in Eurointervention (2006;2:181-186) showed the efficacy of surgical ‘edge-to-edge’ valve therapy. There was a freedom from reoperation and recurrent mitral regurgitation of about 80% at 12 years, which validates the utility of an isolated ‘edge-to-edge’ approach in select patients.”
Additionally, there is a percutaneous clip strategy, in which a transseptal guide catheter maneuvers a metal clip into the mitral orifice and attaches it to the leaflets.
“After placement of a single clip, you can see virtually complete obliteration of the regurgitation,” Feldman said. “An important feature of this device is that two clips can be used. This is a fundamental difference between surgical and percutaneous strategies. [There is] a potential for serial therapy, where patients can have clips placed a number of months apart from each other in the event of recurrent mitral regurgitation.”
EVEREST II
Feldman discussed the EVEREST II trial, which compares this percutaneous clip strategy with surgery. Preliminary data from 92 patients indicated that patients had 95% freedom from adverse events at 30 days (Figure). Researchers also observed eight partial clip detachments.
Future steps
New research must address the lack of intention-to-treat data, and further studies must validate a better assessment of mitral regurgitation. The current assessment is primarily visual, although there are semiquantitative echocardiography assessment criteria.
“We have made no real advances in the way we quantitate mitral regurgitation,” Feldman said.