Mechanical treatment for functional (or secondary) mitral regurgitation (FMR), is being addressed now more than any time previously in history. In this month’s Journal of Invasive Cardiology, Dr. Klein and his group from Leipzig (who honored me by allowing me to assist as a coauthor) have presented their series of patients using the second most widely used percutaneous device to treat FMR, the Carillon Mitral Contour System. Although MitraClip is not approved for use in FMR in the US, MitraClip is most commonly used outside the US to treat FMR, accounting for approximately 2/3 of MitraClip cases. The recently reported follow-up of the CTSN (Cardiothoracic Surgical Trials Network) has cast concerns over the use of surgical mitral repair in treating FMR due to an unexpectedly high recurrence of MR in follow-up. It is interesting with this context to note that the group from Leipzig found that there was a tendency to improvement in MR over time with the Carillon device, unlike the worsening over time seen with surgery. These observations of MR improvement are consistent with the published findings from the safety and efficacy studies of the Carillon device, supporting those unexpected findings. It is unclear what causes this seeming paradox (MR improvement with Carillon over time versus MR worsening with surgically placed annular rings), although many possible theories may be entertained. First, the MR reduction at the time of surgery is excellent, so deterioration is the only possible avenue, although the degree of worsening after surgery has been surprising to many. Why would an indirect annuloplasty be associated with improvement in MR, whereas a direct annuloplasty be associated with worsening? One possibility is that the flexible Carillon device allows for greater dynamic functioning of the mitral annulus, which is inhibited by a rigid surgical ring. Some have postulated that dynamic functioning of the mitral annulus is underappreciated in the mechanism of mitral valve functioning. Additional studies will need to be done to evaluate this mechanism to understand if it is playing a role. One may also wonder if cardiopulmonary support or other insults at the time of cardiac surgery may have an impact in patients with underlying cardiomyopathic conditions, accelerating cardiac deterioration – a phenomenon not impacted by a percutaneous therapy such as Carillon.
Another important observation in this observational post-market study is the inclusion of patients who were not studied in the previous safety and efficacy studies. For example, the prior safety and efficacy studies only examined patients with ejection fractions less than 40%, yet the mean ejection fraction was 40% in this study, and went all the way to include patients with normal ejection fractions. This experience, as well as at other centers using Carillon commercially, has caused Cardiac Dimensions, Inc. (the company making Carillon) to expand the evaluation of such patients in the ongoing randomized, blinded study, REDUCE FMR (being done in Europe, Australia, and New Zealand) to now include patients with ejection fractions up to 50% (similar to what is being done in COAPT). The excellent results seen in this Leipzig study suggest that patients with less severe disease than studied in the previous studies may also benefit from this therapy.
Disclosure: Dr. Steven Goldberg is a consultant and Chief Medical Officer for Cardiac Dimensions, Inc., the maker of the Carillon Mitral Contour System.
Read the entire study here:
Norbert Klein, MD; Dietrich Pfeiffer, MD, Prof; Steven Goldberg, MD; Maika Klein, MD. Mitral Annuloplasty Device Implantation for Non-Surgical Treatment of Mitral Regurgitation: Clinical Experience After the Approval Studies. J INVASIVE CARDIOL 2016;28(3):115-120. Epub 2016 January 15.