Background

Heart valve diseases especially affect the elderly population and are, therefore, expected to become more prevalent in the next decades. Apart from aortic valve stenosis, mitral valve regurgitation (MR) is the most common valvular disease. Transcatheter mitral valve therapies, such as edge-to-edge repair with the MitraClip system, have emerged as a viable treatment option in elderly patients at a high surgical risk, that are deemed unsuitable for heart valve surgery due to concomitant comorbidities and frailty. According to the current guidelines, an assessment of MR severity is based on an integrated approach that includes qualitative, semiquantitative, and quantitative echocardiographic parameters. Additionally, the symptomatic status as well as an assessment of the surgical risk is decisive for the treatment strategy in patients fulfilling the echocardiographic criteria. However, there are no recommendations or risk assessment tools that consider right heart remodeling or damage caused by severe mitral regurgitation. 

Objectives

In this multicenter study, we sought to characterize and classify right heart remodeling in patients with severe mitral valve regurgitation undergoing a MitraClip procedure and evaluated the impact of a newly defined staging classification on the outcome.

Methods

Between September 2010 and February 2019, 929 consecutive patients with severe symptomatic mitral valve regurgitation underwent a MitraClip procedure at the Heart Center Bonn, Cologne, or Düsseldorf and could be included in this study. According to echocardiographic parameters, these patients were classified into four stages: severe MR without right heart damage (Stage 0), with moderate-to-severe tricuspid regurgitation (TR) (Stage 1), with right ventricular dysfunction defined as a reduced fractional area change < 35% and a tricuspid annular plane systolic excursion < 17mm (Stage 2), or with right heart damage with increased right atrial area > 25cm² and/or indexed right ventricular volume > 30ml/m² (Stage 3). We compared clinical outcomes between the four stages and performed a multivariate analysis to evaluate the predictive value of the extent of cardiac damage. 

Results

All-cause mortality rates within one year were associated with an advanced stage of right heart remodeling (Stage 0: 8% vs. Stage 1: 9.7% vs. Stage 2: 15.5% vs. Stage 3: 18.5%; p = 0.005), as shown in Figure 1. In multivariate analyses, the more advanced right heart remodeling stages were independently predictive for one-year all-cause mortality (Stage 2: p = 0.05; Stage 3: p = 0.003). The logistic EuroSCORE was significantly associated with mortality in univariate analysis, contrary to the new staging classification, however, not independently predictive for one-year all-cause mortality.

Conclusion

Right heart remodeling and the extent of cardiac damage is associated with an adverse outcome in patients undergoing a MitraClip procedure to treat severe mitral valve regurgitation as represented in Figure 2. A simple staging classification objectively characterizes the extent of right heart remodeling caused by MR and allows risk prediction in these patients.

 

Figure 2