Evolution of mitral regurgitation after transcatheter tricuspid valve replacement in patients with tricuspid regurgitation

• Applicant: Dr. Ionut Alexandru Patrascu
• Subject Area: Cardiology, Angiology
• Term: from 2024 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 545263014

Background. Severe tricuspid valve regurgitation (TR) is a common finding in elderly patients, which are often turned down for surgery due to extensive comorbidities. Symptomatic isolated TR has thus been managed for decades by medical therapy alone, which does not stop the natural progression of the disease. This unmet clinical need of treating TR has led to the recent development of transcatheter tricuspid valve interventions, whether repair or replacement, with the former already mentioned by current guidelines and the latter just last year receiving CE marking. Unlike transcatheter edge-to-edge tricuspid valve repair (T-TEER), transcatheter tricuspid valve replacement (TTVR) abolishes TR, which can lead to short- and long-term hemodynamical adaptations, including increased left heart filling with consequent progression of pre-existing mitral regurgitation (MR). Aim. The goal of this project is to: 1) define the natural history and evolution of pre-existing mild or moderate functional MR in patients undergoing TTVR, 2) determine if patients with non-severe MR benefit from TTVR, and if MR is a prognostic marker for clinical outcomes. Context and Relevance. Atrioventricular (AV) valve regurgitation mostly occurs as a pair, as there is a wide range of hemodynamic interactions between the pulmonary and systemic circulations. The common scenario is represented by severe MR indirectly causing TR of different extent, with the latter having the potential to indirectly improve after MR treatment, depending on the magnitude of right heart remodeling and pulmonary adaptations. The opposite scenario, where TR is the leading AV valve disease, while MR is moderate or mild, is also common but certainly less understood. With the very recent introduction of TTVR, we are at a crossroads in AV valve therapy, where we finally have the possibility to abolish TR, but are not sure if this might lead down a path of further hemodynamic deterioration. Presuming the right ventricle (RV) is compliant with the immediate decrease in RV stroke volume post-TTVR, effective forward flow in the pulmonary artery should increase, with consequent increased left ventricular filling and possible worsening of preexisting MR, which might counterbalance the potential benefits of TR elimination and prevent improvement in quality of life. This situation seems to be unique to TTVR, as isolated surgical tricuspid valve replacement is extremely rare and always performed on cardiopulmonary bypass, while surgical and especially transcatheter repair procedures almost always leave behind residual TR. Hence it is important to understand which TTVR patients with preexisting moderate-or-less MR benefit from the procedure and how MR can serve patient selection and act as a prognostic marker. This analysis could also help us understand when to consider a ‘combined’ versus ‘staged’ approach in patients with concomitant MR and TR.

• DFG Programme: WBP Fellowship
• International Connection: Canada
• Host: Dr. Neil Fam