Mitral and Tricuspid Regurgitation: Timing Intervention in Heart Failure

Functional mitral regurgitation (FMR) and functional tricuspid regurgitation (FTR) are common complications of left ventricular (LV) and right ventricular (RV) dysfunction, respectively, frequently observed in patients with heart failure (HF). FMR results from geometric changes in the LV, leading to incomplete coaptation of anatomically normal mitral valve leaflets. Similarly, FTR often develops secondary to RV dilation and dysfunction, causing annular dilatation and leaflet tethering. Both conditions contribute to volume overload, further exacerbating ventricular remodeling and HF symptoms. The presence of moderate to severe FMR or FTR is independently associated with increased morbidity and mortality in HF patients. However, the exact point at which surgical or transcatheter intervention provides a benefit beyond optimized guideline-directed medical therapy (GDMT) is a subject of ongoing investigation.

Current guidelines generally recommend intervention for severe, symptomatic FMR or FTR that persists despite optimal GDMT. The challenge lies in identifying patients who might benefit from earlier intervention, before the development of irreversible ventricular damage or severe symptoms. The concept of a 'tipping point' implies a stage where the natural history of the disease shifts, and intervention becomes more effective than continued medical management alone. This point is difficult to define due to the heterogeneity of HF etiologies, patient comorbidities, and the progressive nature of ventricular remodeling.

Intervention Strategies and Outcomes

For FMR, both surgical mitral valve repair or replacement and transcatheter mitral valve repair (TMVr), primarily using edge-to-edge repair devices, are available. Surgical repair is typically considered in patients undergoing concomitant coronary artery bypass grafting (CABG) or those with severe symptoms and suitable anatomy. TMVr offers a less invasive option for high-surgical-risk patients. Studies evaluating TMVr in symptomatic HF patients with severe FMR have demonstrated significant reductions in mitral regurgitation severity, improvements in functional status, and reductions in HF hospitalizations. However, a consistent mortality benefit has not been universally observed across all trials, particularly in those with less severe baseline regurgitation or more advanced LV dysfunction. The COAPT trial, for example, showed a reduction in HF hospitalizations and mortality with TMVr in symptomatic HF patients with severe FMR and suitable anatomy, emphasizing patient selection. Conversely, the MITRA-FR trial, which enrolled a similar population but with different inclusion criteria for LV size and MR severity, did not demonstrate a significant difference in mortality or HF hospitalizations.

For FTR, surgical repair or replacement has historically been reserved for patients undergoing left-sided valve surgery or those with severe, symptomatic FTR and progressive RV dysfunction. Transcatheter tricuspid valve intervention (TTVI) is an emerging field, with various devices under investigation, including leaflet coaptation devices, annuloplasty rings, and valve replacement systems. Early data from registries and small trials suggest that TTVI can reduce TR severity and improve symptoms in carefully selected patients. However, the long-term efficacy and impact on mortality and HF hospitalizations are still being evaluated. The complexity of tricuspid valve anatomy and the often-advanced stage of RV dysfunction at presentation pose significant challenges for effective intervention.

The 'tipping point' for intervention in FMR and FTR likely involves a confluence of factors, including the severity of regurgitation, the degree of ventricular remodeling and dysfunction, the presence and severity of symptoms, and the patient's overall clinical status and comorbidities. Early intervention in asymptomatic or mildly symptomatic patients with moderate FMR or FTR, before significant ventricular dilation or irreversible myocardial damage occurs, remains an area of active research. The challenge is to identify biomarkers or imaging parameters that can predict which patients will progress rapidly and benefit most from early intervention versus those who can be managed effectively with GDMT alone. The risk-benefit profile of intervention must be carefully weighed against the potential for complications, especially in a population often characterized by advanced age and multiple comorbidities.