JACC: CASE REPORTS VOL. 4, NO. 23, 2022 ª 2022 THE AUTHORS. PUBLISHED BY ELSEVIER ON BEHALF OF THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION. THIS IS AN OPEN ACCESS ARTICLE UNDER THE CC BY-NC-ND LICENSE (http://creativecommons.org/licenses/by-nc-nd/4.0/). GUEST EDITOR’S PAGE Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement How to Prevent It? Xavier Armario, MD,a Thomas Modine, MD, PHDb T ranscatheter mitral valve (TMVR) has emerged as an alternative to sur- replacement gical mitral valve replacement (SMVR) for the treatment of mitral valve disease.1 Among its possible of a Sapien 3 (Edwards Lifesciences) or Tendyne (Tendyne Holdings) THV.4,5 Nonetheless, further studies are required to determine a more precise threshold for the neo-LVOT area in the setting of complications, left ventricular outflow tract (LVOT) TMVR. The aortomitral angle, the angle between the obstruction can be a life-threatening situation and is aortic annulus and the mitral annulus, also is a rele- associated with procedural morbidity and mortality. vant anatomic factor, as an obtuse angle (ie, angle The incidence of LVOT obstruction during TVMR is >90  ) seems to increase the risk of LVOT obstruction. relatively low. Nonetheless, in those patients with se- Finally, other important anatomic factors to be vere mitral annular calcification, the incidence of considered are the left ventricle size and septal wall LVOT obstruction with hemodynamic compromise thickness. has been reported to be higher (9.3%).2 On the other Once a patient is identified to be at high risk of hand, the rates of LVOT obstruction are greater in LVOT obstruction after TMVR, a septal ablation valve-in-ring procedures (8.0%) compared with technique may be considered to prevent this valve-in-valve procedures (2.6%).3 complication. Alcohol septal ablation (ASA) has been Identification of those patients at high risk of LVOT used successfully before TMVR for this purpose. 6 obstruction related to TVMR is crucial. Therefore, However, some patients might not be suitable for pre-procedural planning and imaging assessment this technique. Radiofrequency septal ablation (RSA) including echocardiography and cardiac multislice is a novel technique that could be safe and effective computed tomography (MSCT) is essential. Multiple in reducing the risk of LVOT obstruction in patients anatomic factors should be evaluated when deter- undergoing TMVR when ASA is not feasible. mining the risk of LVOT obstruction after TMVR. One Hiltner et al 7 described a case of RSA performed of the most important anatomic factors is the neo- before transcatheter mitral valve-in-valve replace- LVOT size, defined as the estimated residual LVOT ment (VIV-TMVR) in a patient with high risk of LVOT area after the implantation of the transcatheter heart obstruction. RSA was performed successfully and valve (THV). It is a dynamic structure, the size of without complication, under general anesthesia and which changes significantly throughout the cardiac guided by intracardiac echocardiography. A new car- cycle, which is why it should be measured in systole. diac MSCT after RSA showed an enlargement of the Although there is no established cutoff value that neo-LVOT. Subsequently, the patient underwent VIV- works for all of the available THVs, a neo-LVOT area TMVR successfully, with implantation of a 26-mm >1.7 to 1.9 cm 2 appears to be safe for the implantation Sapien 3 THV via transeptal access. Post-procedure echocardiography showed normal left ventricle function and adequate mitral valve function with no From the aDepartment of Cardiology, Hospital Universitari Germans Trias LVOT obstruction. Similarly, Killu et al8 described a i Pujol, Barcelona, Spain, Universitat Autònoma de Barcelona, Barcelona, Spain; and the bDepartment of Cardiology, Hôpital Cardiologique de Haut case of RSA performed to prevent LVOT obstruction Lévêque, Bordeaux, France. in a native-valve TMVR. The case presented in this ISSN 2666-0849 https://doi.org/10.1016/j.jaccas.2022.10.002 2 Armario and Modine JACC: CASE REPORTS, VOL. 4, NO. 23, 2022 Guest Editor’s Page DECEMBER 7, 2022:101663 issue of JACC: Case Reports is the first report of RSA FUNDING SUPPORT AND AUTHOR DISCLOSURES performed in a prosthetic-valve VIV-TMVR. TMVR is a promising therapy, its numbers Dr Armario has reported that he has no relationships relevant to the contents of this paper to disclose. Dr Modine is a consultant for increasing with improvements and iterations of Boston Scientific, Medtronic, Edwards Lifesciences, MicroPort, Gen- current devices. The risk of LVOT obstruction eral Electric, and Abbott; and has received a research support grant should be thoroughly assessed with the use of from Edwards Lifesciences. echocardiography and cardiac MSCT in all patients undergoing TMVR. Further studies are needed to determine the anatomic limitations for each of ADDRESS FOR CORRESPONDENCE: Dr Xavier available devices. Particularly, a more precise Armario, Carretera de Canyet, s/n, 08916, Badalona, threshold for the neo-LVOT area should be defined Barcelona, Spain. E-mail: xavierarmario@gmail.com. for each device. Twitter: @xarmario. REFERENCES 1. Regueiro A, Granada JF, Dagenais F, Rodés- 4. Reid A, Ben Zekry S, Turaga M, et al. Neo-LVOT 7. Hiltner E, Shukla A, Patel P, et al. Radio- Cabau J. Transcatheter mitral valve replacement: and transcatheter mitral valve replacement: frequency ablation for prevention of outflow tract insights from early clinical experience and future expert recommendations. J Am Coll Cardiol Img. obstruction in percutaneous mitral valve-in-valve challenges. J Am Coll Cardiol. 2017;69(17):2175– 2021;14(4):854–866. replacement. JACC Case Rep. 2022;4(19):1247– 2192. 1251. 5. Murphy DJ, Ge Y, Don CW, et al. Use of cardiac 2. Guerrero M, Dvir D, Himbert D, et al. Trans- computerized tomography to predict neo–left 8. Killu AM, Guerrero M, Siontis KC, et al. A novel catheter mitral valve replacement in native mitral ventricular outflow tract obstruction before technique—prophylactic septal radiofrequency valve disease with severe mitral annular calcifica- transcatheter mitral valve replacement. 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