Percutaneous mitral repair as treatment in HFrEF (MitraClip/TEER) classification

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Nehal Eid, M.D.[2]

Classification

Classification framework

Classification of mitral regurgitation (MR) in patients considered for mitral transcatheter edge-to-edge repair (M-TEER) requires three complementary descriptions:

  • MR etiology and mechanism
  • MR severity nomenclature
  • The class of transcatheter intervention and the standardized classification of its result

M-TEER is the procedural class; MitraClip and PASCAL are device platforms within that class.[1]

Etiologic and mechanistic classification

Primary versus secondary MR

Classification Defining abnormality Typical leaflet-motion pattern Mechanistic relationship to HFrEF
Primary (degenerative) MR Intrinsic abnormality of the mitral leaflets or chordae, commonly prolapse or flail Commonly Carpentier type II MR originates from structural disease of the mitral apparatus rather than ventricular remodeling; primary MR may coexist with heart failure with reduced ejection fraction (HFrEF)
Secondary (functional) MR Failure of leaflet coaptation caused by left ventricular or left atrial remodeling without a primary leaflet or chordal lesion Commonly type IIIb in ventricular secondary MR and type I in atrial secondary MR Ventricular remodeling is the principal mechanism in HFrEF-associated secondary MR

The distinction between primary and secondary MR is fundamental because their mechanisms, evaluation, and therapeutic pathways differ. When the mitral apparatus is structurally normal, significant MR is classified as secondary and its ventricular or atrial mechanism should be specified.[2][3]

Ventricular versus atrial secondary MR

Phenotype Dominant chamber abnormality Common clinical setting Typical Carpentier type
Ventricular secondary MR (vSMR) Left ventricular remodeling with papillary-muscle displacement and leaflet tethering Ischemic or nonischemic cardiomyopathy, commonly with HFrEF IIIb; annular dilation may add a type I component
Atrial secondary MR (aSMR) Left atrial and mitral-annular dilation without primary leaflet disease Persistent atrial fibrillation or restrictive atrial remodeling, usually with preserved left ventricular systolic function I

The randomized HFrEF evidence base applies principally to vSMR. The 2020 ACC/AHA guideline identifies persistent NYHA class II–IV symptoms despite optimal guideline-directed medical therapy, left ventricular ejection fraction of 20%–50%, left ventricular end-systolic diameter ≤70 mm, pulmonary artery systolic pressure ≤70 mm Hg, and appropriate valve anatomy as the COAPT-derived selection framework for M-TEER in secondary MR.[4] These criteria should not be transferred automatically to aSMR without consideration of its distinct mechanism and anatomy.

Observational outcome data for aSMR are discordant. One cohort found mortality intermediate between degenerative MR and vSMR, whereas another reported fewer major adverse cardiac events with aSMR than vSMR.[5][6]

In the PASCAL REPAIR study (n=915; 166 aSMR and 749 vSMR), MR ≤1+ was achieved in 77.2% and 71.4%, respectively (P=0.162), with technical success rates of 97.0% and 98.3%. Overall 1-year survival was similar (88.4% versus 86.0%; P=0.346). Baseline tricuspid regurgitation of at least moderate severity was associated with lower 1-year survival in aSMR (84.3% versus 100.0%; P=0.041), but not significantly in vSMR (83.9% versus 89.3%; P=0.051), identifying a phenotype-specific prognostic distinction.[7]

Carpentier leaflet-motion classification

Leaflet motion should be classified separately from leaflet morphology and MR etiology.[2]

Carpentier classification
Type Leaflet motion Representative mechanism Relationship to secondary MR in HFrEF
I Normal Annular dilation; leaflet perforation or cleft Commonly describes aSMR; annular dilation may contribute to vSMR
II Excessive Prolapse or flail Usually indicates primary degenerative MR rather than isolated vSMR
IIIa Restricted during systole and diastole Rheumatic, radiation-associated, carcinoid, or drug-induced valve disease Not the usual mechanism of HFrEF-associated vSMR
IIIb Restricted during systole Ventricular remodeling with papillary-muscle displacement and leaflet tethering Predominant leaflet-motion pattern in ischemic and nonischemic vSMR

Proportionate versus disproportionate MR

The proportionate/disproportionate framework relates MR severity—particularly effective regurgitant orifice area (EROA) and regurgitant volume—to left ventricular end-diastolic volume and systolic function rather than interpreting regurgitant severity in isolation.[8]

Classification Description Illustrative operational anchor
Proportionate MR Regurgitant severity is approximately commensurate with the degree of left ventricular dilation and dysfunction At an ejection fraction of 30%, left ventricular end-diastolic volume of 220–250 mL, and regurgitant fraction of 50%, the expected EROA is approximately 0.3 cm²
Disproportionate MR Regurgitant severity is greater than expected for the degree of left ventricular dilation and dysfunction An EROA of 0.3–0.4 cm² with a left ventricular end-diastolic volume of only 160–200 mL

These values illustrate the proposed construct and are not validated diagnostic cutoffs. COAPT participants had an EROA approximately 30% larger and left ventricular volumes approximately 30% smaller than participants in MITRA-FR.[8]

The framework remains hypothesis-generating and should not be used as a stand-alone M-TEER selection criterion. A COAPT echocardiographic substudy reported treatment benefit across multiple baseline measures, whereas a post hoc analysis of a small subgroup resembling MITRA-FR patients, in whom MR was judged proportionate to ventricular dilation, did not demonstrate benefit.[3][9]

MR severity nomenclature

MR severity is commonly expressed using either ACC/AHA disease stages or the 0-to-4+ grading system. Quantitative echocardiographic thresholds and measurement methods are addressed in the echocardiography microchapter and should not be inferred from grade labels alone.[4]

MR severity nomenclature
System Categories
ACC/AHA stages of chronic secondary MR Stage A: at risk
Stage B: progressive MR
Stage C: asymptomatic severe MR
Stage D: symptomatic severe MR
MR grade 0: none or trace
1+: mild
2+: moderate
3+: moderate-to-severe
4+: severe

Categorization as mild, moderate, or severe depends on data quality and integration of multiple echocardiographic parameters with the clinical findings; not every criterion for a category will be present in every patient. Two-dimensional transthoracic PISA may underestimate the true EROA in secondary MR because the proximal convergence is crescentic rather than circular, and regurgitant-volume thresholds may be lower in low-flow states.[4]

The 0-to-4+ system is used in M-TEER trials and procedural reporting.[10] The United States secondary-MR labeling for MitraClip is likewise expressed in ASE grade terms as MR ≥Grade III, which is why the 0-to-4+ system remains operative regulatory vocabulary alongside ACC/AHA staging.[11]

Classification of the procedural result

The Mitral Valve Academic Research Consortium (MVARC) defines a hierarchy of outcome classifications that should be used precisely rather than as interchangeable synonyms for procedural success.[10]

MVARC outcome classification
Term Assessment point Core requirements
Technical success Exit from the catheterization laboratory No procedural mortality; successful access, delivery, and retrieval of the delivery system; successful deployment and correct positioning of the first intended device; and no emergency surgery or device- or access-related reintervention
Device success 30 days and all later intervals No procedural mortality or stroke; proper device placement; no unplanned device- or access-related intervention; no structural, functional, or device-specific technical failure; and optimal or acceptable MR reduction without significant mitral stenosis, defined by post-procedure effective orifice area ≥1.5 cm² and mean transmitral gradient <5 mm Hg, with no greater than mild (1+) paravalvular MR and no associated hemolysis
Procedural success 30 days Device success without a major device- or procedure-related serious adverse event, including death, stroke, life-threatening bleeding, major vascular or cardiac structural complication, stage 2 or 3 acute kidney injury, myocardial infarction or coronary ischemia requiring revascularization, severe hemodynamic or respiratory failure requiring invasive support, or valve dysfunction requiring repeat intervention
Patient success 1 year Device success; return to the preprocedural living setting; no rehospitalization or reintervention for the underlying condition; NYHA improvement ≥1 functional class; 6-minute walk improvement ≥50 m; and Kansas City Cardiomyopathy Questionnaire improvement ≥10 points

Optimal versus acceptable MR reduction

MVARC result Definition
Optimal MR reduction Post-procedure MR is absent or trace
Acceptable MR reduction MR is reduced by at least one grade from baseline and to no more than moderate (≤2+)

The original MVARC consensus noted that the relative prognostic effects of residual 2+, 1+, and absent MR required further study; therefore, optimal and acceptable reduction should be reported separately whenever possible.[10]

Classification of transcatheter mitral interventions

M-TEER is one subtype of transcatheter mitral repair and should not be used as a synonym for all transcatheter mitral interventions.[1]

Intervention class Subtype or examples Taxonomic distinction
Leaflet-based repair M-TEER using MitraClip or PASCAL Approximates the anterior and posterior leaflets. Regulatory scope differs by platform: MitraClip carries a United States secondary-MR indication, whereas the PASCAL Precision approval issued in 2022 was for primary degenerative MR; secondary-MR clinical studies were subsequently undertaken.[12][13][14]
Annuloplasty Direct annuloplasty Acts directly on the mitral annulus; not M-TEER
Annuloplasty Indirect annuloplasty Remodels the annulus through adjacent structures; not M-TEER
Chordal intervention Transcatheter chordal repair or replacement Targets the chordal apparatus, principally in primary MR; not M-TEER
Valve replacement Transcatheter mitral valve replacement (TMVR) Replaces rather than repairs the native valve

Anatomic suitability for M-TEER is conventionally classified visually as likely successful, challenging, or not likely to be successful.[15]

Device-specific feasibility anchors include anterior and posterior leaflet lengths ≥6.0 mm for MitraClip NT/NTW, 9 mm for XT/XTW, and ≥8 mm for PASCAL; a baseline mean transmitral gradient <5 mm Hg at a heart rate of 60–80 beats/min and mitral valve area ≥4.0 cm² are desirable to limit post-procedural mitral stenosis. These measurements are cross-referenced here for classification only and require full treatment in the echocardiography findings microchapter.[16]

References

  1. ↑ 1.0 1.1 Hahn RT, Lindenfeld J, Lim SD, Mack MJ, Burkhoff D (2024). "Structural Cardiac Interventions in Patients With Heart Failure: JACC Scientific Statement". Journal of the American College of Cardiology. 84 (9): 832–847. doi:10.1016/j.jacc.2024.05.061.
  2. ↑ 2.0 2.1 Bonow RO, O'Gara PT, Adams DH; et al. (2020). "2020 Focused Update of the 2017 ACC Expert Consensus Decision Pathway on the Management of Mitral Regurgitation". Journal of the American College of Cardiology. 75 (17): 2236–2270. doi:10.1016/j.jacc.2020.02.005.
  3. ↑ 3.0 3.1 O'Gara PT, Mack MJ (2020). "Secondary Mitral Regurgitation". The New England Journal of Medicine. 383 (15): 1458–1467. doi:10.1056/NEJMcp1903331.
  4. ↑ 4.0 4.1 4.2 Otto CM, Nishimura RA, Bonow RO; et al. (2021). "2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease". Journal of the American College of Cardiology. 77 (4): e25–e197. doi:10.1016/j.jacc.2020.11.018.
  5. ↑ Yoon SH, Makar M, Kar S; et al. (2022). "Outcomes After Transcatheter Edge-to-Edge Mitral Valve Repair According to Mitral Regurgitation Etiology and Cardiac Remodeling". JACC: Cardiovascular Interventions. 15 (17): 1711–1722. doi:10.1016/j.jcin.2022.07.004.
  6. ↑ Claeys MJ, Debonnaire P, Bracke V; et al. (2021). "Clinical and Hemodynamic Effects of Percutaneous Edge-to-Edge Mitral Valve Repair in Atrial Versus Ventricular Functional Mitral Regurgitation". The American Journal of Cardiology. 161: 70–75. doi:10.1016/j.amjcard.2021.08.062. PMID 34794621 Check |pmid= value (help).
  7. ↑ von Stein P, Stolz L, Haurand JM; et al. (2025). "Transcatheter Edge-to-Edge Repair for Atrial and Ventricular Secondary Mitral Regurgitation: Insights From the REPAIR Study". JACC: Cardiovascular Interventions. 18 (16): 2020–2032. doi:10.1016/j.jcin.2025.05.031.
  8. ↑ 8.0 8.1 Grayburn PA, Sannino A, Packer M (2019). "Proportionate and Disproportionate Functional Mitral Regurgitation: A New Conceptual Framework That Reconciles the Results of the MITRA-FR and COAPT Trials". JACC: Cardiovascular Imaging. 12 (2): 353–362. doi:10.1016/j.jcmg.2018.11.006. PMID 30553663.
  9. ↑ Packer M, Grayburn PA (2020). "New Evidence Supporting a Novel Conceptual Framework for Distinguishing Proportionate and Disproportionate Functional Mitral Regurgitation". JAMA Cardiology. 5 (4): 469–475. doi:10.1001/jamacardio.2019.5971.
  10. ↑ 10.0 10.1 10.2 Stone GW, Adams DH, Abraham WT; et al. (2015). "Clinical Trial Design Principles and Endpoint Definitions for Transcatheter Mitral Valve Repair and Replacement: Part 2: Endpoint Definitions—A Consensus Document From the Mitral Valve Academic Research Consortium". Journal of the American College of Cardiology. 66 (3): 308–321. doi:10.1016/j.jacc.2015.05.049. PMID 26184623.
  11. ↑ Bonow RO, O'Gara PT, Adams DH; et al. (2020). "2019 AATS/ACC/SCAI/STS Expert Consensus Systems of Care Document: Operator and Institutional Recommendations and Requirements for Transcatheter Mitral Valve Intervention". Journal of the American College of Cardiology. 76 (1): 96–117. doi:10.1016/j.jacc.2019.12.002. PMID 31857196.
  12. ↑ Lander MM, Brener MI, Goel K; et al. (2023). "Mitral Interventions in Heart Failure". JACC: Heart Failure. 11 (8 Pt 2): 1055–1069. doi:10.1016/j.jchf.2023.07.016.
  13. ↑ U.S. Food and Drug Administration. Summary of Safety and Effectiveness Data: PASCAL Precision Transcatheter Valve Repair System (P220003). 2022. https://www.accessdata.fda.gov/cdrh_docs/pdf22/P220003B.pdf
  14. ↑ Lurz P, Schmitz T, Geisler T; et al. (2024). "Mitral Valve Transcatheter Edge-to-Edge Repair: 1-Year Outcomes From the MiCLASP Study". JACC: Cardiovascular Interventions. 17 (7): 890–903. doi:10.1016/j.jcin.2024.02.022.
  15. ↑ O'Gara PT, Grayburn PA, Badhwar V; et al. (2017). "2017 ACC Expert Consensus Decision Pathway on the Management of Mitral Regurgitation: A Report of the American College of Cardiology Task Force on Expert Consensus Decision Pathways". Journal of the American College of Cardiology. 70 (19): 2421–2449. doi:10.1016/j.jacc.2017.09.019.
  16. ↑ Little SH, Quader N, Brady M; et al. (2026). "Guidelines for the Intraprocedural Imaging for Mitral Valve Transcatheter Edge-to-Edge Repair (M-TEER): Recommendations From the American Society of Echocardiography". Journal of the American Society of Echocardiography. 39 (6): 529–550. doi:10.1016/j.echo.2026.03.003.
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