Progress Limited in Transcatheter Repair of Mitral Regurgitation



CHICAGO – Within narrow limits, transcatheter repair of mitral regurgitation can have outcomes meeting or even exceeding those of surgery.

"I believe that mitral regurgitation is mostly a surgical disease, but that interventional devices will, sooner or later, be able to manage some of the spectrum of mitral pathology," said Dr. Howard C. Herrmann at the Heart Valve Summit 2012. Dr. Herrmann is professor of medicine and director of interventional cardiology and cardiac catheterization at the University of Pennsylvania, Philadelphia.

Dr. Howard C. Herrmann

"Transcatheter approaches are always going to be somewhat more limited than surgery," said Dr. Herrmann. The device that repairs a leaflet edge to edge is very different from the one that can be used to perform indirect annular dilatation via the coronary sinus, he noted.

Two devices relevant to those indications show promise, although neither is yet approved by the Food and Drug Administration (FDA), he said. These are Cardiac Dimensions’ Carillon for annular dilatation, and Abbott Vascular’s MitraClip for leaflet repair.

In the European TITAN clinical trial, 36 of 53 patients (68%) were implanted with the Carillon Mitral Contour System. The average baseline ejection fraction of all 53 patients was 28%, which Dr. Herrmann characterized as true functional mitral regurgitation (FMR). The prospective, nonrandomized, double-arm study compared results from the implanted group to results from a group without implants.

Implanted patients demonstrated significant reductions in FMR as assessed by multiple quantitative measures, including mean regurgitant volume, which decreased from 34.5 +/– 11.5 mL to 17.4 +/– 12.4 mL over 12 months (P less than .001) (Eur. J. Heart Fail. 2012;14:931-8).

These and other reductions correlated with symptomatic improvement, said Dr. Herrmann. However, the coronary sinus approach to percutaneous mitral annuloplasty is clearly limited by the variable anatomy between the coronary sinus and the posterior mitral annulus, as well as by the risk of coronary artery constriction, he said. Additionally, the long-term benefit of a surgical partial circumference ring is unknown (Circulation 2006;114:377-80).

The other device, the MitraClip, was evaluated in the EVEREST II trial for safety and efficacy in treatment of mitral valve regurgitation.

"Clearly, if you look at the primary effectiveness rate as defined by the trial, which is not a very high bar, surgery still beat the device," said Dr. Herrmann. However, he noted, the device clearly beat surgery in terms of morbidity and other safety end points.

"But when you look at it from an intent-to-treat analysis, those results are clearly inferior with MitraClip: At 2 years, 78.2% of percutaneous patients are free from mitral valve surgery, versus 96.1% of surgery patients (P less than .001).

"MitraClip should not and is not being used for low-risk patients with degenerative disease amenable to surgical repair. ... That said, in the patients who had good results with MitraClip, those results do appear to be fairly durable," he said. At 3 years, all-cause mortality was very similar between the two interventions. (J. Thorac. Cardiovasc. Surg. 2012;143:S60-3; J. Am. Coll. Cardiol. 2012;59:130-9).

Analysis of the high-surgical-risk cohort (n = 78) from EVEREST II revealed a 45% decrease in rehospitalizations (P = .02) at 12 months after intervention with MitraClip, said Dr. Herrmann. This finding led investigators to launch the COAPT trial, which has been approved by the FDA and is expected to start soon in the United States. Approximately 420 patients with significant FMR, thought to be at extremely high risk for surgery, will be randomized 1:1 to MitraClip (n = 210) or medical therapy (n = 210). The primary end point is a reduction in subsequent heart failure hospitalizations.

"This is truly a trial looking at palliative benefit, not mortality," he said.

He concluded by noting that several devices are under development, including others for leaflet repair, indirect annuloplasty, and direct annular or left ventricular remodeling; as well as direct LV shape-altering devices, transcatheter mitral valve replacement devices, and devices that mimic surgical ring annuloplasty.

The Heart Valve Summit was an educational program presented jointly by the American Association for Thoracic Surgery and the American College of Cardiology Foundation. Dr. Hermann has grant/research support from Abbott Vascular, Edwards Lifesciences, St. Jude Medical, Medtronic, and Gore, and has received consulting fees and honoraria from these and other device companies. His presentation was not sponsored.

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