Transcatheter therapies for mitral regurgitation: A professional society overview from the american college of cardiology, the american association for thoracic surgery, society for cardiovascular angiography and interventions foundation, and the society of thoracic surgeons

Transcatheter aortic valve replacement (TAVR) has transformed the care of patients with aortic stenosis. The dissemination of this technology after its approval in the United States in the wake of a pivotal randomized trial 1, 2 has thus far proceeded in a thoughtful and circumspect manner, guided by a coalition of stakeholders dedicated to the delivery of high-quality, patient-centered care. It is anticipated that a number of transcatheter therapies for mitral regurgitation (MR) will also become available for clinical use in selected patients. As an example, the MitraClip device (Abbott Vascular, Santa Clara, California) was approved October 24, 2013, for the reduction of significant (≥3+), symptomatic, degenerative MR in highly anatomically selected patients considered by an experienced heart team to be at prohibitive risk for mitral valve surgery. Other transcatheter approaches in development include mitral annulus–based therapies, transapical neochordal implants, valve-in-valve and valve-in-annuloplasty ring therapies, and valve replacement therapies. A process similar to that adopted for TAVR is proposed to ensure that such innovative treatments are introduced into medical practice in the United States with appropriate safeguards 3. The American College of Cardiology (ACC), the American Association for Thoracic Surgery (AATS), The Society of Thoracic Surgeons (STS), and the Society of Cardiovascular Angiography and Interventions (SCAI) Foundation have collaborated to write this overview to set the stage for an ensuing series of documents, to be joined by other professional societies, and to address the issues critical to the appropriate integration of transcatheter MR therapies into the care of selected patients with this disorder. In accordance with the ACC's policy on relationships with industry and other entities (RWI), relevant author disclosures are included in Appendix 1 of this document. In the spirit of full disclosure, authors' comprehensive RWI information, which includes RWI not relevant to this document, is available online as a data supplement to this document (see Supplementary online material). RWI restrictions do not apply to participation in the external peer review process for clinical documents, in order to ensure that a variety of constituencies/perspectives inform the final paper. However, for purposes of full disclosure, all relevant RWI for reviewers, as well as their individual affiliations, are published in Appendix 2. Final review and approval of the document was provided by the respective boards of the 4 professional societies. These organizations are committed to providing guidance on key issues having an impact on clinical care and believe this document will help frame subsequent discussions regarding such technology as it continues to evolve. Catheter-based therapies for valvular heart disease, including balloon valvuloplasty, have been in clinical use for over 3 decades. More recently, transcatheter valve replacement technologies have dramatically altered the approach to children and adults with congenital or post-surgical pulmonic valve disease and to adults with degenerative aortic stenosis. Using the lessons learned from the release of these transformational technologies, this document seeks to highlight the critical issues surrounding adult transcatheter MR therapies to properly align the interests of all relevant stakeholders, including primary care physicians; patients and their families; proceduralists (interventional cardiologists, cardiac surgeons); heart valve, heart failure, and imaging experts; general and geriatric cardiologists; other heart team members; and regulators, payers, professional societies, and industry. In order to promote the expansion of this technology to allow for best patient outcomes, new guidelines and requirements for training, operator credentialing, and institutional policies will be developed. Answers to these questions are complex and influenced in large measure by the number of interested stakeholders. Transcatheter treatment of MR is technically challenging and thus far of limited scope. Maintaining the best interests of patients constitutes the driving force behind any initiative of this type. MR can result from abnormalities in the structure and/or function of 1 or more of the 4 components of the mitral apparatus (leaflets, annulus, chordae tendineae, and papillary muscles/left ventricular [LV] myocardium). Primary MR refers to abnormalities of the leaflets and is most commonly due to myxomatous degeneration, especially in developed countries. With secondary or functional MR, the leaflets are usually normal, and the regurgitation occurs as a consequence of adverse LV remodeling, with papillary muscle displacement, leaflet tethering, and annular dilatation. The prevalence of moderate to severe mitral valve disease (more often regurgitant rather than stenotic) increases as a function of age and exceeds that of aortic valve disease on both a community and population level when assessed by echocardiography 4. Prognosis with MR differs as a function of both etiology and LV function; treatment protocols, including medical interventions and cardiac resynchronization therapy when indicated, must be tailored to the underlying disease substrate. The indications for and timing of surgery for treatment of MR have evolved considerably over the past several decades as both operative techniques and patient outcomes have improved 5, 6. These trends are especially true for patients with severe, degenerative MR of a myxomatous nature for whom valve repair has become the preferred strategy whenever feasible. Isolated valve repair for this indication can now be accomplished through a variety of minimally invasive approaches, including with the use of robotic techniques in highly specialized surgical centers. Patients are interested in pursuing less invasive approaches in the hopes of reducing the burden of perioperative complications and discomfort, without compromising their chances for a successful and durable outcome. Expert mitral valve surgeons may employ several techniques to accomplish this task, including leaflet resection, neochordal construction, prosthetic ring or band insertion, and edge-to-edge leaflet approximation. Emerging transcatheter technologies have attempted to replicate 1 or more of these surgical principles, thus far with varying success in clinical and experimental settings. Perioperative mortality rates for selected, low-surgical-risk patients with severe degenerative MR are now <1% in major referral centers where a successful repair can be accomplished in over 95% of patients with isolated posterior mitral leaflet pathology. Nevertheless, there remains concern that patients with severe, degenerative MR are not referred for surgical intervention in a timely fashion, even in referral centers of excellence 7. On the other end of the spectrum, symptomatic patients with functional MR that is due either to adverse LV remodeling after myocardial infarction or to a nonischemic cardiomyopathic process may benefit from surgical treatment to reduce or eliminate the excess LV volume load. A down-sized annuloplasty repair or chordal-sparing valve replacement is undertaken as dictated by the anatomic and hemodynamic features encountered in an individual patient. Many such patients are considered intermediate-to-high risk for perioperative mortality or major complications. A less invasive approach, in combination with percutaneous coronary intervention for concomitant treatment of important coronary artery disease, may be of value in this setting. The use of transcatheter mitral valve repair in patients with functional MR appears to be both feasible and beneficial for selected patients 8. As these technologies become available for patients with either degenerative or functional MR, it will be important for experienced referral centers and cohesive heart teams to guide their deployment into clinical practice. As well, the short- and long-term efficacy, safety, comparative effectiveness and cost of these technologies must be evaluated through a dynamic registry supported by relevant stakeholders. The heart team approach, as utilized in the landmark SYNTAX (TAXUS Drug-Eluting Stent versus Coronary Artery Bypass Surgery for the Treatment of Narrowed Arteries; NCT00114972) 9 and PARTNER (Placement of Aortic Transcatheter Valve; NCT00530894) 1, 2 trials, and embedded in the management of patients with advanced heart failure, is now an established paradigm for the care of patients with complex coronary or aortic valve disease. This approach was also followed in EVEREST (Endovascular Valve Edge-to-Edge Repair Study), which evaluated the efficacy and safety of the MitraClip 10-12. The key members of the heart team for transcatheter therapies for MR include primary (general) cardiologists, interventional cardiologists, cardiac surgeons, imaging specialists, valve and heart failure specialists, electrophysiologists, cardiac anesthesiologists, catheterization laboratory technologists, perfusionists, nurses, nurse practitioners, physician assistants, care coordinators, research coordinators, administrators, nutritionists, physical therapists, exercise physiologists, and social workers. At times, it will be appropriate to include a geriatric cardiologist or geriatrician, particularly when assessing frailty/comorbidities of the older adult; additional consultants may be required (nephrology, neurology, or oncology). A heart team leader is responsible for the coordination and integration of these several contributors. The initial diagnosis and management of the patients with MR resides with the primary cardiologist whose clinical decision making is informed by echocardiographic imaging, other imaging, and exercise data as needed. He or she will determine the timing of referral for intervention and then work with the interventional cardiologist and cardiac surgeon to determine the best course of action based on an individualized risk/benefit analysis and an understanding of patient values and preferences. The primary cardiologist is often in the best position to communicate with the family throughout the care process and will provide longitudinal follow-up after the procedure, in coordination with the interventionalist and surgeon. Accurate assessment of mitral valve anatomy and function requires a portfolio of imaging capabilities, including 2- and 3-dimensional transthoracic and transesophageal echocardiography and cardiac magnetic resonance imaging. Quantitative assessment of the severity of mitral valve disease using several imaging capabilities is essential before the procedure and at follow-up. Additional insights are to be gained through coronary angiography (either invasive or noninvasive) and delineation of the anatomic relationship between the coronary sinus and the mitral annulus. Standardized datasets should be collected and the American Society of Echocardiography definitions of severe MR 11 should be incorporated in registry reporting. The need for other arterial or venous imaging will be driven by the specific mitral valve technology and its method of delivery. It is essential for the imaging specialist to be skilled in providing live imaging capabilities because they are often required to assist in the procedure. Heart valve and heart failure specialists are important contributors to the heart team. The perspective of a heart failure specialist is particularly appropriate for the assessment and management of patients with MR and LV systolic dysfunction of any etiology. The interventional cardiologist will be skilled in all aspects of transcatheter structural and coronary heart disease procedures. He or she will work collaboratively with the other members of the heart team in the evaluation and procedural management of the patient, as well as with early post-procedural follow-up. Knowledge of mitral valve disease, imaging, hemodynamics, procedure specifics, adjunct medications, and complications is mandatory. Specific competencies will be addressed in a forthcoming multisocietal document. The cardiac surgeon will see patients in collaboration with the primary and interventional cardiologist and be competent in catheter-based and surgical approaches to MR, including repair and replacement options. Specific competencies will be addressed in a forthcoming multisocietal document. It is recognized that some surgeons have experience with and expertise in catheter-based techniques gained through TAVR procedures. The cardiac surgeon and interventional cardiologist will collaborate during the performance of transcatheter mitral procedures and will designate the primary and secondary operator as appropriate for the specific findings and challenges encountered in any individual patient. Many cardiac catheterization and cardiac surgical programs have a low volume of structural heart disease cases. In low-volume centers, for example, mitral valve replacement may be performed more frequently than appropriate for management of patients with degenerative MR for whom repair is strongly recommended. In addition, patient outcomes vary inversely as a function of operator and institutional volume 12, 13. The National Institutes for Health and Clinical Excellence in the United Kingdom have recommended volume criteria for mitral valve repair 14. The challenges of evaluating and managing patients with MR and significant comorbidities, such as heart failure, require multidisciplinary team care in a high-volume referral center with the infrastructure necessary to ensure best outcomes. The example established by the dissemination of TAVR should pertain to the release of therapies for MR. Accordingly, a detailed list of facilities and personnel experience, pre- and post-procedural care protocols, and complication management strategies must be developed and maintained. All data must be standardized and sent to a central registry for analysis and reporting. The level of commitment needed at the institutional level to establish and maintain the program cannot be overstated. A cardiac catheterization laboratory with adequate space (∼800 sq ft) to accommodate the operators, imagers, cardiac anesthesiologists, support staff, and their necessary equipment (including transesophageal echocardiography equipment, anesthesia machines, and intra-aortic balloon pumps) is mandatory. There must be high-quality, single-plane fluoroscopy and cineangiography. Other imaging modalities, such as computed tomography and magnetic resonance imaging with real-time 3-dimensional reconstruction, are expected to play an increasing role during the procedure. A hybrid operating suite is not strictly necessary for mitral procedures at this stage of development, but laminar air flow to provide operating room–level sterility is mandatory. a transcatheter mitral valve replacement a hybrid suite with the for be needed. 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The and are committed to the of collaboratively as professional and in with the and industry to innovative mitral valve technologies into clinical practice as by the and in the best interests of patients. American College of Cardiology and and Clinical Clinical Clinical The American Association for Thoracic Surgery Society for Cardiovascular Angiography and Interventions Foundation The Society of Thoracic Surgeons