Reply: Subvalvular Repair for Ischemic Mitral Regurgitation: Setting up the Endgame (2021)

The authors reported no conflicts of interest.The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest. The authors reported no conflicts of interest. The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest. The debate surrounding treatment of ischemic mitral regurgitation (MR) has ceased to yield for valid reasons. The randomized Cardiothoracic Surgical Trials Network comparing mitral valve (MV) repair with replacement for severe ischemic MR suggests chordal-sparing replacement is the preferred option, given the unfavorable rates of recurrent MR in the repair group (1 year: 32.6% vs 2.3%, P < .001; 2 years: 58.8% vs 3.8%, P < .001).1Goldstein D. Moskowitz A.J. Gelijns A.C. Ailawadi G. Parides M.K. Perrault L.P. et al.Two-year outcomes of surgical treatment of severe ischemic mitral regurgitation.N Engl J Med. 2016; 374: 344-353Crossref PubMed Scopus (529) Google Scholar,2Acker M.A. Parides M.K. Perrault L.P. Moskowitz A.J. Gelijns A.C. Voisine P. et al.Mitral-valve repair versus replacement for severe ischemic mitral regurgitation.N Engl J Med. 2014; 370: 23-32Crossref PubMed Scopus (609) Google Scholar Furthermore, no significant survival advantage was discovered between surgical approaches at 1 or 2 years, although the study was not powered to definitively conclude if there was. In effort to study a more “complete” MV repair, comparison of restrictive annuloplasty with coronary revascularization versus restrictive annuloplasty plus papillary muscle approximation and coronary revascularization was pursued.3Nappi F. Lusini M. Spadaccio C. Nenna A. Covino E. Acar C. et al.Papillary muscle approximation versus restrictive annuloplasty alone for severe ischemic mitral regurgitation.J Am Coll Cardiol. 2016; 67: 2334-2346Crossref PubMed Scopus (123) Google Scholar Here too, no significant difference in mortality was discovered, even at 5 years. The study's primary end point of absolute change in left ventricular end-diastolic diameter (–5.8 ± 4.1 mm vs –0.2 ± 2.3 mm, P < .001) and secondary end point of change in ejection fraction (8.8 ± 5.9% vs 2.5 ± 4.3%, P < .001) did favor incorporation of papillary muscle approximation to the MV repair. Xu and colleagues4Xu D. McBride E. Kalra K. Wong K. Guyton R.A. Sarin E.L. et al.Undersizing mitral annuloplasty alters left ventricular mechanics in a swine model of ischemic mitral regurgitation.J Thorac Cardiovasc Surg. November 6, 2020; ([Epub ahead of print])Abstract Full Text Full Text PDF Scopus (11) Google Scholar are to be commended for their excellent investigation of a preclinical ischemic MR model. Here, they demonstrated papillary muscle approximation in conjunction with an undersized mitral annuloplasty yielded improved valvular and ventricular mechanics versus annuloplasty alone. This reinforces the notion to pursue treating the subvalvular apparatus since ischemic MR is a disease of the ventricle. Unfortunately, the numerous strategies to treat the subvalvular apparatus from novel devices and ingenious surgical techniques have yielded no definitive standard.5Stock S. Scharfschwerdt M. Warnecke R.J. Richardt D. Tsvelodub S. Sievers H.H. New device for the treatment of functional ischemic mitral regurgitation: proof of concept in an in vitro model.Thorac Cardiovasc Surg. 2019; 67: 531-537Crossref PubMed Scopus (1) Google Scholar, 6Wagner C.E. Kron I.L. Subvalvular techniques to optimize surgical repair of ischemic mitral regurgitation.Curr Opin Cardiol. 2014; 29: 140-144Crossref PubMed Scopus (8) Google Scholar, 7Kron I.L. Green G.R. Cope J.T. Surgical relocation of the posterior papillary muscle in chronic ischemic mitral regurgitation.Ann Thorac Surg. 2002; 74: 600-601Abstract Full Text Full Text PDF PubMed Scopus (253) Google Scholar Despite our best intentions, no clinical trials have demonstrated a significant advantage for a particular surgical approach. The 2016 update to the American Association for Thoracic Surgery consensus guidelines for ischemic MR posit MV repair or replacement may be considered, although at this time, replacement is preferred.8Kron I.L. LaPar D.J. Acker M.A. Adams D.H. Ailawadi G. Bolling S.F. et al.AATS Ischemic Mitral Regurgitation Consensus Guidelines Writing Committee2016 update to The American Association for Thoracic Surgery (AATS) consensus guidelines: ischemic mitral valve regurgitation.J Thorac Cardiovasc Surg. 2017; 153: e97-e114Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar As our understanding of this heterogenous disease process improves, incorporation of risk prediction models and careful patient selection may tip the scales toward repair of severe ischemic MR.9Nappi F. Lusini M. Avtaar Singh S.S. Santana O. Chello M. Mihos C.G. Risk of ischemic mitral regurgitation recurrence after combined valvular and subvalvular repair.Ann Thorac Surg. 2019; 108: 536-543Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar,10Kron I.L. Hung J. Overbey J.R. Bouchard D. Gelijns A.C. Moskowitz A.J. et al.Predicting recurrent mitral regurgitation after mitral valve repair for severe ischemic mitral regurgitation.J Thorac Cardiovasc Surg. 2015; 149: 752-761.e1Abstract Full Text Full Text PDF PubMed Scopus (154) Google Scholar We agree that attention to the subvalvular apparatus is warranted but stand by the notion that robust data must be gleaned before defining the best approach.11Nappi F. Spadaccio C. The use of subvalvular repair for ischemic mitral regurgitation: is it finally coming of age?.J Thorac Cardiovasc Surg Open. 2021; 8: 290-291Scopus (3) Google Scholar In addition, a subvalvular approach will depend on individual measurements, which have yet to be standardized. When we can answer whether combining annular and subvalvular repair techniques leads to improved survival with acceptable freedom from recurrent MR over MV replacement, we will be ever closer to calling checkmate on severe ischemic MR. The use of subvalvular repair for ischemic mitral regurgitation: Is it finally coming of age?JTCVS OpenVol. 8PreviewWe congratulate Xu and colleagues1 on this excellent experimental work on the mechanical effect of restrictive annuloplasty (RMA) and subvalvular apparatus surgery in ischemic mitral regurgitation (IMR).1 The authors reinforced and substantiated with experimental evidence concepts expressed in biomechanical models2,3 and that also emerged from previous retrospective studies in IMR4-7 and the major randomized trials, as the Papillary Muscle Approximation (PMA) trial8,9 and CTSNet trial.10 Undersizing RMA could lead to impairment of ventricular mechanics and torsion by deforming the mitral annulus. Full-Text PDF Open Access