The Impact of Residual MR After Percutaneous Mitral Repair

Effective therapy for functional mitral regurgitation (FMR) has been elusive. Surgical repair as a stand-alone therapy has a high failure rate within the first year. The invasiveness of open surgery balanced by relatively disappointing effectiveness has limited the use of isolated mitral repair or replacement for FMR. Less invasive approaches for FMR are thus attractive. Cardiac resynchronization therapy (CRT) is the only widely available treatment that has shown a clear benefit for both symptoms and mortality. Unfortunately, many patients are not candidates for CRT and CRT treated patients respond only half the time.¹ The development of other less invasive FMR therapies has been ongoing for the last decade. To date, three device therapies for FMR have received CE approval. MitraClip and Carillon have been in global use for several years. Recently, the Valtech Cardioband system received CE approval.

In this month’s issue of the Journal of Invasive Cardiology, Klein et al’s real-world clinical experience with Carillon represents the first series of patients treated with this device outside of the trial environment.² The effectiveness of the therapy for reduction of MR is similar to that reported in the approval registry trials,^3,4 with an acute reduction in MR grade from 2.8+ to 1.9+. Importantly, an acute reduction of coronary artery flow in the circumflex was noted in over 40% of patients. This could be managed successfully in all but 1 patient with either device repositioning or placement of a shorter length device. Another critical observation in this report is the treatment of 1 patient with a preexisting CRT implant. These findings support use of a less invasive coronary sinus implant, balanced by some residual MR. While all of the current percutaneous MR devices use general anesthesia, the Carillon is the only one that requires jugular and coronary sinus access, and is probably the simplest compared with the MitraClip and Cardioband, which both require transseptal access.

There are several limitations to the Carillon apparent in this report. This is a small series with only 17 patients treated since 2012. The selection biases that resulted in this particular population must be substantial. While circumflex compression was successfully managed acutely in this group, it is clearly an important procedural consideration and a larger experience with Carillon will be needed to understand the potential for late coronary compression. Another unexplained finding in this registry and in the prior published experience with this device is the continued improvements and MR severity and clinical benefits between the time of implantation and late follow-up as late as 1 year. One of the advantages of MitraClip and Cardioband is the ability to assess MR reduction at the time of device implant. This late improvement seen after Carillon implantation will need to be better understood. 

A fundamental question regarding catheter-based repair devices is whether they have any role at all as we see the development of transcatheter mitral valve replacement (TMVR). The clear appeal of TMVR is complete effectiveness at eliminating MR. What remains to be seen is if TMVR devices are as safe as repair devices that may be less effective at reducing MR, and whether these reductions in MR are ultimately associated with clinical benefits. In this report, the Carillon device leaves residual MR, and at the same time leads to significant symptom improvement. This finding is also the case for MitraClip, where in a randomized trial, despite lesser reductions in MR grade compared with surgery, the improvements in LV remodeling, quality of life, and symptoms were similar to surgery.⁵ It seems intuitive that the complete elimination of MR by mitral replacement would be better than any intervention that leaves some residual MR, but the experience from the repair technologies makes this less clear.⁶ While the role of mitral repair for degenerative MR is clear, we continue to struggle with whether treating FMR in the setting of LV dysfunction is ultimately beneficial.

References

1.    Auricchio A, Schillinger W, Meyer S, et al; for the PERMIT-CARE Investigators. Correction of mitral regurgitation in nonresponders to cardiac resynchronization therapy by MitraClip improves symptoms and promotes reverse remodeling. J Am Coll Cardiol. 2011;58:2183-2189.

2.    Klein N, Pfeiffer D, Goldberg S, Klein M. Mitral annuloplasty device Implantation for non-surgical treatment of mitral regurgitation: clinical experience after the approval studies. J Invasive Cardiol. 2016;28:115-120. Epub 2016 Jan 15. 

3.    Schofer J, Siminiak T, Haude M, et al. Percutaneous mitral annuloplasty for functional mitral regurgitation: results of the AMADEUS Trial. Circulation. 2009;120:326-333.

4.    Siminiak T, Wu JC, Haude M, et al. Treatment of functional mitral regurgitation by percutaneous annuloplasty: results of the TITAN trial. Eur J Heart Fail. 2012;14:931-938.

5.    Feldman T, Foster E, Glower D, et al; for the EVEREST II Investigators. Percutaneous repair or surgery for mitral regurgitation. N Engl J Med. 2011;364:1395-1406.

6.    Maisano F, Alfieri O, Banai S, et al. The future of transcatheter mitral valve interventions: competitive or complementary role of repair vs replacement? Eur Heart J. 2015;36:1651-1659. Epub 2015 Apr 12.

__________________________________________

From the NorthShore University HealthSystem, Evanston, Illinois.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Feldman reports grants from Boston Scientific, Edwards Lifesciences, and Abbott Vascular. Dr Guerrero reports no conflicts of interest regarding the content herein.

Address for correspondence: Ted Feldman, MD, MSCAI, FESC, FACC, Evanston Hospital, Cardiology Division-Walgreen Building 3rd Floor, 2650 Ridge Ave, Evanston, IL 60201. Email: tfeldman@tfeldman.org