Background

Transcatheter valve therapies (TVT) have emerged as a viable treatment option for high-risk patients with severe mitral valve regurgitation (MR), deemed unsuitable for heart valve surgery This patient cohort is usually suffering from several comorbidities including coronary artery disease (CAD). The prevalence of CAD in patients with severe MR has been reported to range between 30% and 84.2% in different registries investigating outcome after MitraClip procedure.

In patients undergoing mitral valve surgery and coronary artery bypass grafting (CABG), survival has already been shown to be associated with the extent of coronary artery disease. However, the impact of CAD and revascularization on outcome in patients undergoing percutaneous mitral valve repair using the MitraClip system remains uncertain and is still matter of debate. 

Objectives

In this retrospective observational study, we sought to evaluate the prevalence and impact of concomitant coronary artery disease and the impact of complete revascularization on outcome in patients undergoing percutaneous valve repair with the MitraClip system.

Methods

Between September 2010 and July 2019, 444 consecutive patients with severe symptomatic MR underwent percutaneous valve therapy using the MitraClip system at the Heart Center Bonn. All patients underwent interdisciplinary discussion within the local, institutional Heart Team and were deemed unsuitable for open heart surgery due to concomitant comorbidities (such as porcelain aorta), frailty, advanced age and/or previous open heart surgery resulting in high surgical risk. To assess the extent of coronary artery disease, we retrospectively calculated the SYNTAX Score at baseline (SS) and after revascularization (rSS). For the statistical analysis, we stratified patients according to the baseline SYNTAX Score and residual SYNTAX Score into two groups: SYNTAX Score <= 3 vs. SYNTAX Score > 3 and rSS = 0 vs. rSS > 0. Finally, we compared outcome between the groups.

Results

Comparing rates of one-year all-cause mortality between the different baseline SS levels, we observed a significant association between the extent of CAD and mortality (SS > 3: 22% vs. SS <= 3: 9.6%; p < 0.001). Comparing rates of all-cause mortality between the different rSS levels, we also found a significant association between the extent of remaining CAD burden and mortality (rSS > 0: 31.4% vs. rSS = 0: 9.9%; p < 0.001), as presented in Figure 1A. Patients with a rSS of 0 had a more favorable outcome. To further evaluate the effect of revascularization on outcome, we performed a sub-analysis and compared outcome between the different rSS groups substratified according to the baseline SYNTAX Score. In this analysis, we found that patients who underwent complete revascularization had an outcome comparable to those who had no or a low CAD burden at baseline, as shown in Figure 1B. In multivariate analysis, the residual SYNTAX Score has been shown to be an independent predictor for one-year all-cause mortality (p < 0.001), as well as alanin aminotransferase (ALT) (p = 0.02), and NT-pro BNP (p < 0.001).

Conclusion

The complexity of CAD, as assessed by the SYNTAX Score, is associated with outcome in patients undergoing a MitraClip procedure. The burden of residual CAD after PCI is an independent predictor of one-year all-cause mortality. Patients undergoing complete revascularization had the most favorable outcome independent of MR etiology.