Tricuspid regurgitation (TR) is an increasingly recognized valvular heart disease associated with high morbidity and mortality. With the availability of various novel transcatheter tricuspid interventions, it is no longer considered a "forgotten valve." Heart failure with preserved ejection fraction (HFpEF) is a prevalent condition also characterized by high morbidity and mortality. The prevalence of moderate to severe TR in the general population is 3% to 6%; however, in patients with heart failure (with reduced or preserved ejection fraction [EF]), the prevalence is 10% to 29%, rising to up to 39% in patients with HFpEF and atrial fibrillation (AF). The EuroTR registry, an international registry including patients who underwent percutaneous treatment for severe TR, reported that 72% of patients had a left ventricular ejection fraction (LVEF) ≥50%. In a subgroup of patients with right heart catheterization data, 68% had a pulmonary capillary wedge pressure (PCWP) ≥15 mm Hg, indicating that many of these patients may have HFpEF. Patients with significant TR have also been shown to experience irreversible liver derangement and cirrhosis. Non-invasive evaluation of liver stiffness (LS), measured by transient elastography, has recently received increased attention in patients with heart failure and has been shown to closely correlate with right-sided filling pressures. LS has been used to predict adverse outcomes in patients undergoing transcatheter aortic valve (TA) surgery with concomitant left-sided valve surgery.

On the other hand, the Remote Dielectric Sensing System (ReDS; Sensible Medical Innovations, Israel) is a device that measures lung fluid non-invasively and provides an objective and reproducible index of volume status. It is an FDAapproved device for heart failure patients. ReDS measurements are presented as the percentage of fluid relative to lung volume, with normal values ranging between 20% to 35%. Studies have demonstrated excellent correlations between the ReDS index and computed tomography (CT)-measured lung water and invasively determined hemodynamics. Additionally, it has been shown to predict heart failure rehospitalization in patients with acute heart failure.

Given the emergence of novel transcatheter tricuspid interventions and the established link between TR, HFpEF, and markers such as liver stiffness and lung fluid index (measured by ReDS), this study will examine the intricate interplay between these conditions and their shared pathophysiology. By analyzing left and right heart function, risk factors, and treatment outcomes, the research aims to phenotype TR using non-invasive assessment tools to predict clinical outcomes and improve treatment strategies for patients with different types of TR. Our findings will contribute to developing more effective and personalized treatment plans for patients with TR.

Inclusion Criteria:

• Patients with >=moderate TR
• able to consent for the study.

Exclusion Criteria:

1. LVEF <=40%
2. Have significant left sided organic valvular heart disease (i.e. >=moderate AS, >=moderate MS, >=moderate MR of organic or mixed aetiology), dysfunctional mitral valve replacement or aortic valve replacement
3. Prior tricuspid valve interventions (eg TriClip, tricuspid valve repair or replacement) (To allow accurate transient elastography)
4. Known hepatocellular carcinoma
5. Known portal vein thrombosis
6. Established liver cirrhosis with a known liver-related aetiology
7. Hepatitis C infection and not on treatment
8. Uncontrolled hepatitis (e.g. hepatitis B infection, autoimmune hepatitis)
9. Fatty liver with evidence of non-alcoholic fatty liver disease or cirrhosis (to allow accurate non-invasive lung fluid assessment)
10. recent rib fracture (<3 months) with or without flail chest
11. BMI <20 or >36
12. Height <155cm or >195cm
13. Patients with right lung tumor
14. Patients with right sided pacemaker
15. Patients with known underlying exudative right pleural effusion

By analyzing left and right heart function, risk factors, and treatment outcomes, the research aims to phenotype TR using non-invasive assessment tools to predict clinical outcomes and improve treatment strategies for patients with different types of TR.