The American Society of Echocardiography (ASE) has published new guidance intended to standardize intraprocedural imaging and communication among clinicians performing mitral valve transcatheter edge-to-edge repair (M-TEER).
The guideline, "Guidelines for the Intraprocedural Imaging for M-TEER: Recommendations from the American Society of Echocardiography," was developed by the ASE to address variability in imaging protocols and operator experience as M-TEER procedures are performed across a growing number of centers.
The writing group noted that greater institutional experience has been associated with improved procedural success, shorter procedure times, and fewer procedural complications. The authors also stated that because M-TEER relies heavily on transesophageal echocardiographic (TEE) guidance, variability in intraprocedural imaging can affect procedural success and patient outcomes.
The recommendations focus on intraprocedural imaging and communication rather than the broader question of when to offer M-TEER versus surgery, medical therapy, or other treatment options. The document defines imaging views, procedural steps, and communication points for interventional echocardiographers and interventional cardiology or surgical operators. It covers two-dimensional (2D), biplane, three-dimensional (3D), and 3D multiplanar reconstruction (MPR) imaging.
Most recommendations in the guideline are supported by Level 2 evidence, reflecting writing-group consensus and available observational data. The writing group noted that randomized controlled trial evidence addressing individual procedural elements remains limited or unavailable. The guideline also states that its recommendations should not be used as the sole basis for medical practice decisions.
Stepwise Imaging Protocol
The guideline outlines a stepwise imaging protocol spanning nine stages: baseline evaluation, transseptal puncture, delivery and positioning of the guide catheter, delivery of the repair device, positioning for leaflet grasp, leaflet grasp, evaluation of device performance before deployment, final deployment, and evaluation of iatrogenic atrial septal defects (iASDs).
During baseline evaluation, the guideline advises clinicians to confirm the severity and mechanism of mitral regurgitation (MR), assess ventricular function, plan device selection and implantation strategy, and identify potential contraindications.
The writing group noted that MR severity should be interpreted in the procedural setting because general anesthesia, reduced oral intake, and positive-pressure ventilation may alter hemodynamic loading conditions and affect Doppler assessment. If intraprocedural findings differ substantially from the preprocedural TEE examination, the guideline advises clinicians to attempt to restore near-physiologic loading conditions — typically through pharmacologic blood pressure support or volume loading — before reassessing severity.
For procedural planning, the guideline recommends assessment of MR etiology and severity, mean diastolic gradient, mitral valve area (MVA), leaflet length and morphology, and regurgitant jet location.
Anatomic and Hemodynamic Thresholds
The guideline specifies a baseline transmitral gradient of less than 5 mmHg, assessed at a heart rate of 60–80 beats per minute, as desirable to help minimize the risk of mitral stenosis. An MVA of at least 4.0 cm² is likewise described as desirable. The guideline notes that an MVA below 3.5 cm² is often a contraindication to transcatheter edge-to-edge repair, while an MVA of 3.5–4.0 cm² may still be feasible depending on the patient's body size, the anticipated number and location of devices, and operator experience.
Minimum posterior leaflet length requirements are device-specific: the guideline specifies a length of at least 6.0 mm for a MitraClip NT/NTW device, 9 mm for a MitraClip XT/XTW device, and at least 8 mm for a PASCAL device.
The document characterizes M-TEER eligibility as a multiparametric assessment rather than a series of fixed thresholds. Favorable anatomy includes central valve pathology (A2/P2), adequate leaflet length, preserved leaflet mobility, and sufficient MVA, whereas severe calcification, endocarditis, perforation, and markedly restricted valve anatomy may limit procedural suitability or favor alternative therapies.
Transseptal Puncture and Communication
The guideline identifies transseptal puncture as a critical procedural step and recommends positioning the puncture within the fossa ovalis while maintaining appropriate height and alignment relative to the mitral valve coaptation point. The ideal transseptal puncture site is typically 4.5 to 5.0 cm above the mitral annular plane, though the guideline notes this may be lower for lateral commissural pathology or markedly restricted secondary-MR leaflets, and higher for medial commissural pathology or significant leaflet prolapse. Three-dimensional imaging modalities, particularly 3D MPR, are recommended to improve procedural guidance and communication during this step.
Following transseptal puncture, the guideline outlines echocardiographic guidance for delivery and positioning of the guide catheter (approximately 2 cm of catheter length within the left atrium), delivery of the repair device, identification of gripper or clasp orientation, and device positioning and orientation before leaflet grasp — using a combination of 2D, biplane, 3D, and 3D MPR imaging depending on procedural complexity.
A central theme of the document is standardized communication between interventional echocardiographers and procedural operators. To support consistency, the guideline recommends standardized image orientation and nomenclature throughout the procedure, including displaying the mitral valve commissures at symmetrical clock positions (e.g., 2 o'clock and 10 o'clock) regardless of where the aortic valve falls in the image.
The guideline also assigns an important role to 3D MPR across multiple procedural stages. The writing group states that 3D MPR may make transseptal puncture localization more intuitive, assist with tracking device trajectory and position, and help confirm orientation for leaflet grasp. If a TEE probe cannot be safely advanced into the esophagus or stomach, smaller TEE probes or 3D intracardiac echocardiographic probes may be considered as alternatives for procedural guidance.
Leaflet Grasp and Device Performance
The guideline recommends imaging confirmation of adequate leaflet insertion and tissue capture before device deployment, citing four echocardiographic markers: draping of the leaflets over the device arms or paddles, immobility of the residual leaflet tissue at the grasp site, shortening of visible leaflet tissue compared with adjacent areas, and a "tissue bridge" visible on 3D or transgastric en face imaging.
Before release of the device, the guideline recommends assessing residual MR and the transmitral gradient using a combination of color Doppler, continuous-wave Doppler, pulsed-wave Doppler, and 3D MPR-based orifice area planimetry. A residual mean gradient of less than 5 mmHg and a residual MVA of at least 2.0 cm² are described as preferred targets, while noting that a patient's age and functional status may influence what gradient is considered acceptable.
The guideline states that there are currently no specific guidelines for evaluating MR severity after deployment of an M-TEER device. As a result, the writing group recommends using the same integrative approach applied to native MR, with comparisons made against baseline measurements obtained before intervention.
Following device deployment, imaging should reassess leaflet insertion, tissue bridge robustness, capture of pathologic leaflet segments, effective orifice area, forward gradient, and residual regurgitation. Decisions regarding an additional device should balance further MR reduction against the risk of increased transmitral diastolic pressure gradients.
Iatrogenic Atrial Septal Defects
Persistent iASDs at 6 months were common, occurring in 27% of patients when assessed with transthoracic echocardiography and nearly 50% when assessed with TEE. The guideline cites larger catheter size, longer procedure duration, extensive sheath movement, high left atrial pressure, and left ventricular hypertrophy as suggested predictive factors for this persistence.
Routine closure is not recommended because many defects resolve over time, septal closure devices may complicate future procedures requiring transseptal puncture, and supporting evidence remains limited. Immediate closure at the time of M-TEER may be considered in cases of right-to-left shunting, bidirectional shunting, pulmonary hypertension, new right ventricular dysfunction, or severe tricuspid regurgitation. The guideline notes that eccentric defects may be more likely than round defects to close spontaneously. Defects greater than 1.0 cm are generally considered for closure, with final decisions made on a case-by-case basis.
Endorsements and Disclosures
The document was endorsed by the Society for Cardiovascular Anesthesiologists. The Society for Cardiovascular Angiography & Interventions affirmed the value of the document.
"Until now, there was not a unified, contemporary framework for intraprocedural imaging during M-TEER procedures," said Stephen H. Little, MD, guideline chair, interventional cardiologist, and medical director of the Valve Clinic at Houston Methodist DeBakey Heart & Vascular Center, in an ASE press release. "This guideline establishes a standardized approach to imaging and communication among interventional echocardiographers and interventional cardiology or surgical operators to reduce variability and enhance procedural success."
"Three-dimensional multiplanar reconstruction has become an essential tool for guiding M-TEER procedures with greater precision," said Nishath Quader, MD, guideline co-chair and professor of medicine in the cardiovascular division at Washington University School of Medicine in St. Louis, in the ASE press release. "We hope this guideline encourages its consistent use among imaging specialists involved in these procedures to optimize patient outcomes."
Disclosures: The guideline received no specific grant funding from public or private sources. Several writing group members reported relationships with commercial interests, including Abbott Laboratories, Boston Scientific, Edwards Lifesciences, GE Healthcare, Materialise, Medtronic, Philips Healthcare, Siemens Healthineers, and Wolters Kluwer/UpToDate. Several writing group members reported no actual or potential conflicts of interest related to the guideline.