**4. Transcatheter treatment for mitral valve disease**

#### **4.1. Transcatheter mitral valve repair**

Zhu et al. performed a meta-analysis to compare the short-term outcomes of HCR with those of CABG for multivessel coronary artery disease. They found that HCR was noninferior to CABG in terms of the incidence of death, myocardial infarction, stroke, and renal failure, whereas HCR was associated with less blood transfusion and shorter length of stay in hospital [30]. Halkos et al. compared the outcomes of 147 HCR cases with matched off-pump CABG cases. They reported 5-year survival rate and the incidence of MACCE were similar between HCR and offpump CABG, whereas the need for repeated revascularization was higher in HCR group [31].

For the treatment of severe symptomatic aortic stenosis, surgical aortic valve replacement has been the gold standard. The advent and rapidly widespread adoption of transcatheter aortic valve replacement (TAVR) has now resulted in it becoming the option for patients who would have been considered inoperable or prohibitively high surgical risk [32]. Excellent mid-term

**3. Transcatheter treatment for aortic valve disease**

*Note*: MACCE; major adverse cardiac and cerebrovascular events.

**Table 1.** Outcomes of hybrid coronary revascularization.

**Study Year Number of pts Follow-up** 

Angelini et al. [4]

260 Interventional Cardiology

Leacche et al. [25]

Lewis et al. [54]

Isomura et al. [55]

Presbitero et al. [56]

Repossini et al. [58]

Gilard et al. [59]

Vassiliades et al. [61]

Bonatti et al. [62]

**(months)**

Rab et al. [53] 2012 22 38.8 ± 22 0 0 95

Lee et al. [57] 2004 6 12 0 0 –

Kon et al. [60] 2008 15 12 0 – 93

1996 6 – 0 – 89

2013 80 1 – 2.5 91

1999 14 1.44 0 – 93

2000 37 24 1.4 – 92

2001 42 18 2.4 12.2 83

2007 70 33 1.4 – 97

2006 47 7 0 – 90

2008 5 6 0 – 100

2013 166 64.6 ± 12.0 1.2 12 83 (at 5 years)

**30-day mortality** 

**MACCE (%) Event-free** 

**survival (%)**

**(%)**

The prevalence of mitral regurgitation is higher than other valvular heart diseases [40, 41]. Surgical mitral repair remains the gold standard for patients with primary mitral regurgitation. However, there are a growing number of patients with mitral regurgitation underserved by surgical therapy due to prohibitive surgical risks. The recent development of transcatheter mitral valve technique provides an additional therapeutic option for some high-risk and inoperable patients [42, 43]. The optimal way to adjudicate innovative surgical and interventional mitral therapies is through a robust collaboration within a well-functioning Heart Team which includes not only cardiac surgeons and interventional cardiologists but also imaging specialists.

The current leader in the field of transcatheter mitral repair device is the MitraClip (Abbott Vascular, Santa Clara, CA). This device is delivered in an antegrade transseptal approach across the atrial septum from the femoral vein to achieve an edge-to-edge direct leaflet approximation (**Figure 1**). More than 30,000 patients worldwide have been treated with this procedure to date. In the United States, a Society of Thoracic Surgeons (STS)/American College of Cardiology database analysis of the first 564 cases performed through August 2014 showed the average patient age was 83 years, with a median STS predicted risk of mortality for mitral valve repair and replacement of 7.9 and 10.0%, respectively. The majority of the patients had prohibitive surgical risks such as severe frailty, prior cardiac surgery, and end-stage heart failure. The procedural success rate was 91.8% with a 30-day operative mortality of 5.8% [43].

The randomized EVEREST II trial showed that the need for surgery for residual mitral regurgitation was significantly higher in patients who received MitraClip compared with those who underwent surgery at 1 year and 5 years; however, the MitraClip procedure was associated with superior safety and similar improvements in clinical outcomes [44, 45]. Currently, guidelines state that MitraClip can be considered in patients with severe primary mitral regurgitation who meet the echocardiographic criteria of eligibility, and are judged inoperable or at prohibitive surgical risk by a Heart Team [32, 46]. Further studies are needed to apply this technique to intermediate- or low-risk patients.

In conclusion, the MitraClip procedure has proven reasonable safety and efficacy in high-risk patients and is already considered as an established part of the mitral valve program in highvolume centers. A multidisciplinary Heart Team approach will play a crucial role for careful patient selection and clinical application of the transcatheter interventions as a part of a successful and multimodal mitral valve program [47].

**Figure 1.** MitraClip (Abbott Vascular, Santa Clara, CA) is a percutaneous mitral valve repair using anterior-posterior edge-to-edge direct leaflet approximation.

#### **4.2. Transcatheter mitral valve replacement**

The current leader in the field of transcatheter mitral repair device is the MitraClip (Abbott Vascular, Santa Clara, CA). This device is delivered in an antegrade transseptal approach across the atrial septum from the femoral vein to achieve an edge-to-edge direct leaflet approximation (**Figure 1**). More than 30,000 patients worldwide have been treated with this procedure to date. In the United States, a Society of Thoracic Surgeons (STS)/American College of Cardiology database analysis of the first 564 cases performed through August 2014 showed the average patient age was 83 years, with a median STS predicted risk of mortality for mitral valve repair and replacement of 7.9 and 10.0%, respectively. The majority of the patients had prohibitive surgical risks such as severe frailty, prior cardiac surgery, and end-stage heart failure. The procedural success rate was 91.8% with a 30-day operative mortality of 5.8% [43]. The randomized EVEREST II trial showed that the need for surgery for residual mitral regurgitation was significantly higher in patients who received MitraClip compared with those who underwent surgery at 1 year and 5 years; however, the MitraClip procedure was associated with superior safety and similar improvements in clinical outcomes [44, 45]. Currently, guidelines state that MitraClip can be considered in patients with severe primary mitral regurgitation who meet the echocardiographic criteria of eligibility, and are judged inoperable or at prohibitive surgical risk by a Heart Team [32, 46]. Further studies are needed to

In conclusion, the MitraClip procedure has proven reasonable safety and efficacy in high-risk patients and is already considered as an established part of the mitral valve program in highvolume centers. A multidisciplinary Heart Team approach will play a crucial role for careful patient selection and clinical application of the transcatheter interventions as a part of a suc-

**Figure 1.** MitraClip (Abbott Vascular, Santa Clara, CA) is a percutaneous mitral valve repair using anterior-posterior

apply this technique to intermediate- or low-risk patients.

cessful and multimodal mitral valve program [47].

262 Interventional Cardiology

edge-to-edge direct leaflet approximation.

Unlike transcatheter mitral valve repair, the challenges of deploying and anchoring a functional prosthetic device into the mitral valve annulus amid the intact subvalvular apparatus is more complex. As of January 2016, the total human experience with transcatheter mitral valve replacement implantation surpassed 50 cases, with half of those performed in the United States [43]. The preliminary outcomes have been promising so far.

The Tendyne device (Abbott Vascular, Santa Clara, CA) is a potentially fully retrievable trileaflet porcine pericardial valve with an impermeable nitinol skirt which has a prominent cuff positioned to rest on the intertrigonal aortomitral curtain [48] (**Figure 2**). The Tendyne is an intraannular valve that does not specifically capture the leaflets, and thus the primary clinical target is patients with functional mitral regurgitation. The first US use of Tendyne device was in April 2015. Currently, multiple experienced centers have been chosen for the Food and Drug Administration (FDA) clinical trial for high risk patients inoperable for conventional mitral valve replacement. Several other devices for transcatheter mitral valve replacement are also in the stage of clinical investigation.

Despite continuing innovation, current transcatheter mitral valve replacement delivery systems remain large and the majority require a transapical retrograde approach to the mitral valve. Therefore, the collaboration between interventional cardiologists and surgeons is needed as with the transapical TAVR procedure.

**Figure 2.** Tendyne (Abbott Vascular, Santa Clara, CA) is a transapically delivered porcine pericardial valve for transcatheter mitral valve replacement.
