**2.1. Functional mitral regurgitation and heart failure. Why a percutaneous approach?**

Mitral regurgitation (MR) is one of the most common valvular disease worldwide [5] and its frequency is increasing with the age of the population. Functional MR (FMR) is a consequence of left ventricular (LV) remodeling with structurally preserved mitral valve (MV) leaflets. Significant MR may be present in half of the patients with congestive HF [6] and the development of MR after an acute myocardial infarction or in patients with dilated cardiomyopathy is associated with an increased risk of developing cardiac adverse events [7–11].

Surgery is the treatment of choice for patients with severe MR who refer symptoms or present LV dysfunction (LVD) [12]. However, up to 50% of patients cannot undergo MV surgery due to prohibitive surgical risk, usually related to advanced age, LVD or comorbidities [13]. Moreover, the proportion of patients with FMR undergoing surgical treatment is even lower [14]. Interestingly, open-heart surgery has yielded conflicting results in this sort of patients, with a lack of clear survival benefit and high recurrence rates even with modern techniques [15–18]. On the other hand, conservatively managed unoperated patients have poor clinical outcomes, especially those with FMR, whose mortality can exceed 50% at 5-years follow-up [19]. Large series from Duke University has proved that isolated medical management in patients with ischemic MR is associated with the highest rates of death after 20 years [20]. Thus, patients with FMR managed medically represent a high-risk population with high rates of death and readmission for HF [21]. Percutaneous MV therapies are emerging as an alternative for this population in order to fill a large unmet need.

#### **2.2. Percutaneous mitral valve repair**

The MV has a complex structure and its competence depends on the preservation of the MV leaflets, the subvalvular apparatus, the mitral annulus (MA) and the LV normal shape. Dysfunction of any of these different components may lead to the development of MR [22]. In the last few years, several percutaneous devices have been under investigation, addressing different anatomical and pathophysiological targets involved in MR [23, 24]. Percutaneous ongoing therapies have somehow tried to reproduce any of the already contrasted opensurgery techniques, such as edge-to-edge MV repair (MitraClip®), undersized annuloplasty (Carillon®, Cardioband®, Mitralign®) or chordal implantation (Neochord®). Some of them have gained approval for human use and have been tested in small clinical trials (**Table 1**).


**Table 1.** Summary of commercially available catheter-based therapies for PMVR.

HF are similarly increasing, resulting in very high costs for national health systems [3]. Despite developments in drug therapies and the widespread use of implantable cardiac devices, outcomes remain poor [4]. Several transcatheter implantable devices have recently emerged in an attempt to improve the prognosis and quality of life of such patients. In this chapter, we will review the percutaneous treatment alternatives for mitral and tricuspid regurgitation (TR)

**2. Transcatheter mitral valve intervention in mitral regurgitation**

is associated with an increased risk of developing cardiac adverse events [7–11].

tive for this population in order to fill a large unmet need.

**2.2. Percutaneous mitral valve repair**

**2.1. Functional mitral regurgitation and heart failure. Why a percutaneous approach?**

Mitral regurgitation (MR) is one of the most common valvular disease worldwide [5] and its frequency is increasing with the age of the population. Functional MR (FMR) is a consequence of left ventricular (LV) remodeling with structurally preserved mitral valve (MV) leaflets. Significant MR may be present in half of the patients with congestive HF [6] and the development of MR after an acute myocardial infarction or in patients with dilated cardiomyopathy

Surgery is the treatment of choice for patients with severe MR who refer symptoms or present LV dysfunction (LVD) [12]. However, up to 50% of patients cannot undergo MV surgery due to prohibitive surgical risk, usually related to advanced age, LVD or comorbidities [13]. Moreover, the proportion of patients with FMR undergoing surgical treatment is even lower [14]. Interestingly, open-heart surgery has yielded conflicting results in this sort of patients, with a lack of clear survival benefit and high recurrence rates even with modern techniques [15–18]. On the other hand, conservatively managed unoperated patients have poor clinical outcomes, especially those with FMR, whose mortality can exceed 50% at 5-years follow-up [19]. Large series from Duke University has proved that isolated medical management in patients with ischemic MR is associated with the highest rates of death after 20 years [20]. Thus, patients with FMR managed medically represent a high-risk population with high rates of death and readmission for HF [21]. Percutaneous MV therapies are emerging as an alterna-

The MV has a complex structure and its competence depends on the preservation of the MV leaflets, the subvalvular apparatus, the mitral annulus (MA) and the LV normal shape. Dysfunction of any of these different components may lead to the development of MR [22]. In the last few years, several percutaneous devices have been under investigation, addressing different anatomical and pathophysiological targets involved in MR [23, 24]. Percutaneous ongoing therapies have somehow tried to reproduce any of the already contrasted opensurgery techniques, such as edge-to-edge MV repair (MitraClip®), undersized annuloplasty (Carillon®, Cardioband®, Mitralign®) or chordal implantation (Neochord®). Some of them have gained approval for human use and have been tested in small clinical trials (**Table 1**).

associated with advanced HF.

118 Interventional Cardiology
