The following are key points to remember from a state-of-the-art paper on tricuspid regurgitation (TR): from imaging to clinical trials to resolving the unmet need for treatment.

1. Background: TR is prevalent and associated with high mortality but underdiagnosed and profoundly undertreated by surgery. Challenges in intervention for TR include poor outcomes and TR recurrence after surgical intervention, and persistent or recurrent TR and residual right ventricular (RV) consequences after transcatheter repair. This review addresses TR diagnosis, quantification, multimodality imaging, and management.
2. TR etiologies and mechanisms: TR etiologies include organic (caused by leaflet perforation or cleft, leaflet flail or papillary muscle rupture, or restricted leaflet motion associated with rheumatic or carcinoid disease), iatrogenic (caused by leaflet perforation or restriction after cardiac implanted electronic device [CIED] lead insertion, or leaflet tear or chordal rupture after ablation or CIED lead insertion), or functional (associated with atrial fibrillation, pulmonary hypertension [PH], or RV dysfunction).
3. Diagnostic imaging for tricuspid valve (TV) structure and TR severity:
• Echocardiographic assessment should include TV morphologic assessment and TR causes and mechanism; three-dimensional (3D) echocardiography can be especially useful. TR assessment should be quantitative, with severe TR defined by effective regurgitant orifice area ≥0.40 cm².
• Cardiac magnetic resonance (CMR) imaging can assess TR severity and RV function.
• Computed tomography (CT) can be complementary to transesophageal echocardiography (TEE) for the assessment of TV leaflet anatomy and TR mechanism, and for anatomical measurements associated with intervention.
• Cardiac catheterization can be useful in the assessment of PH.
4. Diagnostic imaging for RV function and cardiac remodeling: RV function and remodeling can be assessed with RV ejection fraction (RVEF) or RV end-systolic volume index (RVESVi) assessed by 3D echocardiography, CMR, or CT; echocardiographic tricuspid annular plane excursion (TAPSE), and RV-pulmonary artery (PA) coupling (measured echocardiographically as the ratio of TAPSE to PA systolic pressure).
5. Intraprocedural monitoring:
• TEE is the imaging modality of choice for the guidance of transcatheter interventions, including tricuspid transcatheter edge-to-edge repair (T-TEER), annular repair, and orthotopic valve replacement.
• Intracardiac echocardiography (ICE) is a potential alternative to TEE.
• Hybrid or fusion imaging, involving the overlay of fluoroscopy and TEE or CT images, also can be used for transcatheter procedural planning and guidance.
6. Post-procedural evaluation:
• Surveillance with transthoracic echocardiography (TTE) after a surgical or transcatheter intervention typically is performed before discharge; 1 month, 6 months, and 1 year after intervention, and then yearly.
• Structural abnormalities including thrombosis, endocarditis, and calcification or degenerative changes can be assessed using TEE or gated CT.
7. Current and developing interventions:
• Tricuspid annuloplasty is the standard of care for surgical intervention. Valve replacement might be preferable in patients with severe RV dilation and distorted subvalvular apparatus.
• T-TEER is the dominant transcatheter intervention for TR. Evolving options for transcatheter intervention include incorporation of a spacer in the T-TEER device, leaflet extensions, subvalvular manipulations, and new devices.
8. Clinical trials and endpoints:
• Because of heterogenous outcomes associated with intervention, clinical staging and scoring systems should integrate TR severity, heart failure severity, and comorbidities. The TRI-SCORE was developed to predict operative mortality for TV surgery, and incorporates clinical data, biomarkers, and echocardiographic parameters.
• Early feasibility studies are pivotal in investigating emerging therapies for TR.
• Five clinical trials in the United States and Europe currently are investigating intervention for TR: CLASP II (T-TEER), TRILUMINATE Pivotal Trial (T-TEER), TRISCEND II Pivotal Trial (transcatheter valve replacement), TRI-FR (T-TEER), and TRIC-I-HF (transcatheter annuloplasty and T-TEER).
9. Future directions:
• The complexity of the TV and the heterogeneity of TR pose challenges to care.
• Awareness of the importance of TR and its assessment and management are important, including referral of patients to tertiary heart valve centers.
• The authors advocate for a change in the paradigm of TR management; with consideration for early and multimodality imaging-based selective treatment to reduce the risks of irreversible RV damage, organ failure, and residual heart failure.

Clinical Topics: Noninvasive Imaging, Valvular Heart Disease

Keywords: Diagnostic Imaging, Heart Valve Diseases, Tricuspid Valve Insufficiency

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