Progression of secondary mitral regurgitation: from heart failure to valvular heart failure

Transcatheter therapies for secondary mitral regurgitation in advanced heart failure: what are we aiming for?

A severe secondary mitral regurgitation (SMR) can be found in a significant portion of patients affected by advanced heart failure (AHF). Conventional therapies (optimal medical therapy, devices, surgery) present restricted clinical efficacy in this stage of the left ventricle disease which is burdened by high mortality and morbidity rates. Although the treatment of choice is represented by heart transplantation (HTx), there is an unmet need related to the limited supply of donor hearts (as opposed to the growing prevalence of AHF) and the low eligibility of highly symptomatic patients. In case of concomitant severe SMR, transcatheter mitral valve therapies (repair and replacement) may play a crucial role in this setting. While a direct prognostic improvement after correction of SMR has yet to be proved, AHF patients can benefit from the following: hemodynamic stabilization, symptomatic relief, normalization of pulmonary arterial pressures, and reduction in hospitalizations for acute heart failure. Obtaining these results may lead to the clinical consequences of reaching the HTx in good enough clinical status (bridge to heart transplantation), becoming eligible for the HTx (bridge to HTx candidacy), and being delisted for clinical improvement (bridge to recovery). Therefore, achieving traditional secondary endpoints in patients with AHF and SMR can translate into significant clinical implications.

Global regurgitant volume: approaching the critical mass in valvular-driven heart failure

AIMS

Recent progress in the diagnosis of functional valve regurgitation forms a coherent perception of severity thresholds by quantitative assessment. However, thresholds focused on either valve in isolation-not accounting for the global haemodynamic burden arising from concomitant functional regurgitation of the mitral and tricuspid valves. We sought to determine whether the global regurgitant volume is associated with adverse cardiac remodelling and mortality.

METHODS AND RESULTS

This long-term observational study included 414 patients on guideline-directed medical therapy. Baseline global regurgitant load defined as the sum of mitral and tricuspid regurgitant volume was assessed by the proximal flow convergence method. All-cause mortality during 5 years follow-up served as the primary endpoint. The median global regurgitant load was 30 mL (interquartile range 15-49) with 67% accounting for mitral and 33% accounting for tricuspid regurgitant volume. The global regurgitant load had significant impact on outcome with a crude hazard ratio of 1.46 (1.28-1.66; P < 0.001) for a 1-SD increase in global regurgitant volume, results that remained virtually unchanged after bootstrap or clinical confounder-based adjustment (P < 0.001 for adjusted models). Spline curve analysis showed a linearly increasing risk with a threshold of 50 mL and sustained increasing risk thereafter.

CONCLUSIONS

The present study demonstrates the detrimental effect of the global regurgitant load in patients with heart failure with reduced ejection fraction. The threshold where heart failure is driven by the valve lesions is a global regurgitant volume of 50 mL with continuously increasing risk beyond that threshold. Future studies need to address whether an attempt to reduce the global regurgitant volume can improve outcome.

Proportionate or disproportionate secondary mitral regurgitation: how to untangle the Gordian knot?

Recent randomised percutaneous mitral intervention trials in patients with heart failure with secondary mitral regurgitation (SMR) have yielded contrasting results. A 'relative load' or 'proportionality' conceptual framework for SMR has been proposed to partly explain the disparate results. The rationale behind the framework is that SMR depends on the left ventricular dimension and not vice versa. In this review, we provide an in-depth analysis of the proportionality parameters used in this framework and also discuss the regurgitant fraction. We also consider haemodynamic observations in SMR that may affect the interpretation and comparisons among proportionality parameters. The conclusion is that the proportionality concept remains hypothetical and requires prospective validation before envisaging its use at individual patient level for risk stratification or therapeutic decision-making.

Valve Disease in Heart Failure: Secondary but Not Irrelevant

Secondary regurgitation caused by the remodeling and dysfunction of the left or right heart chamber may complicate heart failure, worsening both symptoms and prognosis. Outcome studies have shown that patients' prognosis worsened as the severity of secondary regurgitation increases. Imaging and more specifically echocardiography plays a central role for diagnosis and serial assessment of secondary regurgitation as well as for timing the intervention and guiding the procedure.