Changes to the management of patients with secondary mitral regurgitation (MR) are among the key topics featured in a focused update of the 2017 ACC Expert Consensus Decision Pathway on the Management of Mitral Regurgitation. The 2020 Focused Update has been published online at the Journal of the American College of Cardiology.
Some of the changes relate to the U.S. Food and Drug Administration decision in early 2019 to extend the indication for edge-to-edge repair with the MitraClip to include heart failure (HF) patients who have moderate-to-severe functional MR despite treatment with optimal medical therapy. The 2017 consensus pathway limited transcatheter treatment to primary MR.
Among the highlights of the 2020 focused update:
- The new document makes numerous recommendations relating to the transcatheter repair of secondary MR, including its use after documentation of persistent symptoms despite optimal guideline-directed medical therapy for HF with reduced ejection fraction.
- Exercise echo has been added to the list of ancillary testing that may be considered to establish MR severity.
- It now includes the theoretical concept of disproportionate MR as a proposed means of evaluating secondary MR and determine whether a patient might be a candidate for valve directed therapies.
- Consideration of rhythm control in patients with atrial fibrillation is now included, especially those with atrial functional MR.
New Evidence, New Understanding
Many of the updated recommendations derive from trial data. In the case of the recognition of disproportionate MR, it comes from a deeper understanding of a pair of trials evaluating patients with functional mitral regurgitation. Both trials evaluated mitral valve repair using the MitraClip: one was strikingly positive (COAPT), while the other (MITRA-FR) was completely neutral without results that even leaned in that right direction.
Evidence now suggests that the studies actually evaluated patients with two very different types of MR. If MR is caused by left ventricular (LV) dilatation and is proportional to LV end-diastolic volume (LVEDV) – dubbed proportionate MR – then treatment should target the LVEDV. Conversely, if MR is out of proportion to and cannot be explained by LVEDV (disproportionate MR), then treatment must target the valve structure, using techniques like the MitraClip or surgical repair.
In the section on prognosis, the focused update includes a statement noting a possible survival benefit with edge-to-edge repair in selected patients with secondary MR. The authors of the new document state that while surgical correction of secondary MR may improve symptoms and quality of life, it has not been shown to improve survival. They add that transcatheter edge-to-edge clip repair, however, was shown in COAPT to improve both survival and quality of life. Nevertheless, the writing committee noted that the 2-year rate of death or hospitalization for HF with transcatheter and optimal medical therapy in this trial was still 46% (vs. 68% in those managed medically).
The updated decision pathway also expands the multidisciplinary team for consensus decision making to include a cardiologist with experience managing HF and MR in patients with secondary MR.
While only one device is currently approved for MV repair, the writing committee notes that the “field is rapidly evolving and novel devices are very likely to enter into practice in the near future.” As other transcatheter MV repair systems become available, the authors note there will be a need to establish new criteria for patient selection, as well as operator and institutional requirements. Until then, there is a new document, Expert Consensus Systems of Care Document: Operator and Institutional Recommendations and Requirements for Transcatheter Mitral Valve Intervention, which was published online in December 2019 ahead of print.
Bonow RO, O’Gara PT, Adams DH, et al. 2020 Focused Update of the 2017 ACC Expert Consensus Decision Pathway on the Management of Mitral Regurgitation. J Am Coll Cardiol 2020 [Epub before print]
Nishimura RA, Bonow RO. Percutaneous Repair of Secondary Mitral Regurgitation - A Tale of Two Trials. N Engl J Med 2018;379:2374-6. https://www.nejm.org/doi/full/10.1056/NEJMe1812279
Bonow RO, O'Gara PT, Adams DH, et al. 2019 AATS/ACC/SCAI/STS Expert Consensus Systems of Care Document: Operator and Institutional Recommendations and Requirements for Transcatheter Mitral Valve Intervention. J Am Coll Cardiol 2019 Dec 9. doi: 10.1016/j.jacc.2019.12.002. [Epub ahead of print] http://www.onlinejacc.org/content/early/2019/12/08/j.jacc.2019.12.002
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