Significant tricuspid regurgitation (TR) has gained increasing importance in recent years. A clear association has been observed between significant TR and adverse long-term outcomes, including right heart failure, target organ damage, and mortality. Historically, the clinical relevance of this valvular disease has been underestimated, with patients often referred for surgery at advanced stages, carrying substantial surgical risks.
In a recent study on the natural history of patients with moderate or severe TR, a 42% mortality rate was observed over a median follow-up of 2.9 years, with less than 0.5% of patients in this situation (approximately 1.6 million) undergoing surgical intervention annually. Improved outcomes for these patients require a solid understanding of TR pathophysiology, patient selection, and optimal timing for intervention, with echocardiography serving as a pivotal tool in guiding clinical decisions. Duggal and Harris provide a list of ten key considerations for evaluating these patients:
- Tricuspid Valve Anatomy
An understanding of tricuspid valve (TV) structure is essential for planning interventions. The TV, much like the mitral valve, is a structural complex comprising the annulus, leaflets (anterior, posterior, and septal, each varying in size), chordae tendineae, papillary muscles, and right ventricle. Recently, a classification system categorizing four distinct tricuspid leaflet morphologies has been proposed: type 1, the classic and most common form (>50%) with three leaflets; type 2 (<5%), where anterior and posterior leaflets are fused; type 3, with four cusps, subdivided by the location of the extra leaflet (~39% prevalence), where two posterior leaflets represent the second most frequent morphology; and type 4, with more than four leaflets, accounting for around 2.5%.
2. Etiologic Classification of TR
TR can be classified as primary (5-10%) due to congenital or acquired conditions, secondary/functional (>90%) mainly due to annular dilation resulting from left heart disease, or TR related to implanted electronic devices, which is increasingly frequent.
3. Imaging Assessment and Severity Grading of TR
The ideal approach combines qualitative (right chamber or inferior vena cava dilation, abnormal valve structures), semi-quantitative (vena contracta width ≥ 7 mm, proximal isovelocity surface area [PISA] radius > 9 mm at a Nyquist limit of ~30 cm/s), and quantitative measures, with effective regurgitant orifice area (EROA) obtained via PISA being the most accurate. However, this method tends to underestimate TR severity since the regurgitant orifice is non-circular, contrary to echocardiographic assumptions.
4. Echocardiographic Evaluation of the TV
Transthoracic (TTE) and transesophageal (TEE) echocardiography, individually or combined, provide essential information for assessing TR severity, especially in candidates for intervention. TTE often offers sufficient visualization, with parasternal, four-chamber, and subcostal views being the most informative. When further detail is needed or when TTE is inadequate, TEE allows for precise evaluation through mid-esophageal and transgastric views.
5. 3D Echocardiography of the TV
3D echocardiography enhances spatial assessment of both the valve and TR severity, allowing for accurate vena contracta measurements by eliminating geometric errors, and should thus be incorporated into a multiparametric assessment of TR severity.
6. 3D-Guided Multiparametric Evaluation
The spatial accuracy of 3D TEE facilitates the identification of TR etiology and the evaluation of its relationship with implantable device electrodes, enabling intervention success prediction based on electrode-valve interaction.
7. Indications for TV Intervention
Timely intervention is critical. Both the AHA/ACC and ESC guidelines recommend concomitant TV repair in patients with severe TR undergoing left-sided valve surgery (Class I) and in less advanced cases presenting tricuspid annular dilation (end-diastolic diameter >4.0 cm or >2.1 cm/m²) or early signs/symptoms of right-sided failure (Class IIa). Symptomatic patients with persistent right-sided failure symptoms despite optimal medical therapy could also benefit from isolated TV surgery, improving clinical status and reducing heart failure hospitalizations.
In primary severe TR cases with right-sided failure symptoms, early TV intervention should be considered to prevent progressive ventricular remodeling and dysfunction (AHA/ACC Class IIa, ESC Class I). The optimal timing for asymptomatic cases remains debatable; generally, intervention should be considered upon signs of right ventricular dilation/dysfunction to prevent irreversible stages, even in the absence of clinical symptoms.
8. Predictors of Surgical Annuloplasty Failure in TR
Annuloplasty is the preferred surgical approach for secondary TR. However, this technique does not guarantee success; around 10% of patients show moderate or severe TR within five years post-intervention. Predictive factors include extreme annular dilation (>44 mm), coaptation height relative to the annular plane (>0.76 cm), tethering area (>1.63 cm²), persistent pulmonary hypertension post-repair, left ventricular dysfunction (ejection fraction <40%), and right ventricular geometric changes.
9. Echocardiography-Informed Surgical Strategy
For complex TR cases involving multiple mechanisms like leaflet tethering or electrode impingement, additional techniques beyond annuloplasty may be required. Perioperative echocardiography proves invaluable for assessing TR correction adequacy and deciding on further intervention if necessary.
10. Anatomic Suitability for Transcatheter Procedures via Echocardiography
In recent years, percutaneous techniques for symptomatic patients ineligible for surgery have broadened treatment options, including edge-to-edge repair, annuloplasty, heterotopic valve implantation, and orthotopic valve replacement. Echocardiography, primarily TEE, remains central to evaluating anatomical suitability, complemented by other modalities when necessary.
COMMENTARY:
In conclusion, TR is an often underappreciated valvular disease with significant prognostic implications. Early management is critical to avoid surgical intervention in advanced stages with minimal benefit. Echocardiography (TTE and TEE) remains the primary imaging modality for pre-, peri-, and post-operative assessments, supplemented by additional modalities like computed tomography for detailed anatomical analysis. The advent of percutaneous techniques has allowed for improved long-term prognosis and quality of life in patients who would otherwise be inoperable.
REFERENCE:
Duggal N, Harris A. The 10 Commandments for Echocardiography Assessment to Determine Severity and Repairability of the Tricuspid Valve. Innovations (Phila). 2024 Jun 5:15569845241253269. doi: 10.1177/15569845241253269.
