**3. Transcatheter aortic valve replacement (TAVR) for native aortic regurgitation**

TAVR has evolved as a treatment for AS in the United States (U.S.) across all risk categories [19, 20]. More recently, TAVR has been increasingly used for off-label

*Transcatheter Therapies for Aortic Regurgitation: Where Are We in 2023? DOI: http://dx.doi.org/10.5772/intechopen.112679*

indications such as bicuspid AV stenosis, subaortic stenosis, and severe AR [21]. Offlabel TAVR has shown similar 1-year mortality (25.6%) compared to on-label TAVR in a study using STS/TVT data [21].

According to 2020 ACC/AHA valvular heart disease guidelines, SAVR is a class I indication for pure native AR stage C2-D [3]. However, TAVR has been performed as an off-label treatment for AR in patients with prohibitive surgical risk [22]. TAVR poses unique technical challenges in pure AR due to lack of annular/leaflet calcification and, in some cases, aortic root dilation. Current data suggests oversizing the prosthetic valve by 10–15% with caution and not exceeding 20% due to the risk of annular rupture and conduction abnormalities [23–25]. Severe aortic root dilation with large annuli may exceed the size of commercially approved bioprosthetic valves and make the TAVR riskier and unsuccessful due to the risk of valve embolization. Additionally, it may cause more than mild residual PVL due to a lack of proper seal. The maximum size of the commercially available self-expanding valve is 34 mm (Evolut FX by Medtronic), providing a maximal annular area of 940 mm2 [26]. It is larger than the area of the largest commercially available balloon-expandable valve, e.g., 29 mm Edwards SAPIEN 3 Ultra or RESILIA valve provides an annular area of 683 mm2 [27].

Alharbi et al. compared TAVR (n = 912) vs. SAVR (n = 13,808) for pure native AR using the US national inpatient sample database from 2016 to 2017 and found no difference in in-hospital mortality between both groups. Although the need for a permanent pacemaker (PPM) was higher in the TAVR group, these patients had lower acute renal injury, cardiogenic shock, respiratory complications, and length of hospital stay despite having worse baseline characteristics compared to the SAVR group [28]. Another large-scale study by Arora et al [29] demonstrated 3.3% 30-day allcause mortality with TAVR for AR compared with 3.4% in the PARTNER trial for AS in high-risk population [30]. Newer-generation devices depicted lower mortality with higher procedural success of TAVR in pure AR when compared with first-generation devices across observational studies [31–33].

Examples of first-generation TAVR devices include Edwards Sapien XT and Medtronic CoreValve. Second-generation valves have an improved design to provide better anchoring mechanisms, optimal seal, and superior hemodynamic results. Examples of second-generation valves include Edwards Sapien 3, Medtronic Evolut R, Evolut PRO, Evolut FX, Acurate Neo, Acurate TA, Direct Flow Valve, J-valve, JenaValve, and Portico valves.

#### **3.1 Edwards Sapien 3**

The Edwards Sapien 3 valve by Edwards Lifesciences comprises bovine pericardial tissue with a balloon expandable cobalt-chromium frame and an inner and outer skirt. The outer skirt provides more durability and prevents PVL without excessive overexpanding [34]. The valve is designed to be delivered by transfemoral approach via 14 or 16 F sheath, depending on valve size, and is available in sizes 20 mm, 23 mm, 26 mm, and 29 mm. It is not approved for AR but has been used as an off-label indication in selected high-risk patients [35]. A recent observational study showed a 94.6% (n = 35) device success rate and 8.1% all-cause mortality at 30 days using Sapien 3 valve for pure AR with non-calcified leaflets. The valve migration occurred in 10.8% of cases (n = 4) (**Figures 1** and **2**) [36].

#### **Figure 1.**

*Edwards Sapien 3 ultra valve comprises bovine pericardium tissue polyethylene terephthalate outer skirt (credit: Edwards Lifesciences).*

#### **Figure 2.**

*Newer generation Edwards Sapien 3 RESILIA tissue valve with anti-calcification technology (credit: Edwards Lifesciences).*

#### **3.2 Medtronic Evolut**

Medtronic Evolut valve consists of a porcine tissue pericardial valve with a selfexpanding nitinol frame. The latest iteration is the Evolut FX system. It is delivered transfemorally via 14 F or 16 F inline sheath, and available sizes are 23 mm, 26 mm, 29 mm, and 34 mm. The delivery system is designed to fully retrieve the valve for

*Transcatheter Therapies for Aortic Regurgitation: Where Are We in 2023? DOI: http://dx.doi.org/10.5772/intechopen.112679*

**Figure 3.** *Evolut FX 34 mm self-expanding nitinol frame with bovine tissue (credit: Medtronic).*

repositioning. Federal Drug Administration (FDA) has not yet approved it for AR. However, it has been used off-label in patients with AR who are not eligible for surgery with acceptable results (**Figure 3**) [32, 37].
