Is Aiming High Always Best?

Transcatheter aortic valve replacement (TAVR) has rapidly evolved since its introduction, with refinement in both transcatheter heart valve (THV) devices and implantation technique. Major life-threatening complications are now a rare occurrence. While many periprocedural concerns have been addressed, new permanent pacemaker (PPM) implantation remains a concern. A number of patient, device, and implantation factors can influence new PPM rates, of which implantation depth is an important factor. A higher THV implantation has been shown to lead to lower rates of new PPM.1Rodés-Cabau J Ellenbogen KA Krahn AD et al.Management of conduction disturbances associated with transcatheter aortic valve replacement: JACC scientific expert panel.J Am Coll Cardiol. 2019; 74 (doi:10.1016/j.jacc.2019.07.014.): 1086-1106Google Scholar Various strategies can be utilized to achieve a high implantation which vary based on the THV platform utilized.2Tang GHL Zaid S Michev I et al.“Cusp-overlap” view simplifies fluoroscopy-guided implantation of self-expanding valve in transcatheter aortic valve replacement.JACC Cardiovasc Interv. 2018; 11 (doi:10.1016/j.jcin.2018.03.018.): 1663-1665Google Scholar Ramanathan and colleagues present a series of patients implanted using a novel technique utilizing the radiolucent line at the bottom of the SAPIEN 3 valve. Early experience is promising with no new permanent pacemakers in a small series of patients, which included those with preexisting conduction abnormalities.3Ramanathan PK, Nazir S, Elzanaty AM, et al. Novel method for implantation of balloon expandable transcatheter aortic valve replacement to reduce pacemaker rate - Line of lucency method. Struct Heart. 2020. doi:10.1080/24748706.2020.1813355.Google Scholar Further validation will be required in a multicentre experience and a broader anatomical subset of patients. This technique may be beneficial in selected cases such as those at high risk of developing a new conduction disorder, and may reduce the rate of new PPM. However, it is unknown how this technique performs in comparison to the current recommendations from the manufacturer, and thus a randomized prospective multicenter comparison will likely be required. This technique may also not be ideal in certain patients, for example, in those with bicuspid anatomy where the level of the aortic annulus may be challenging to delineate. While implanting high may be desirable from the perspective of new PPM rates, other considerations are equally of concern particularly in patients with longevity who may require future coronary access or redo procedures. This is of increasing importance as TAVR expands to younger patients, with the recent low-risk randomized trials demonstrating that TAVR was equivalent, or even superior to surgical aortic valve replacement (SAVR).4Mack MJ Leon MB Thourani VH et al.Transcatheter aortic-valve replacement with a balloon-expandable valve in low-risk patients.N Engl J Med. 2019; 380 (doi:10.1056/NEJMoa1814052.): 1695-1705Google Scholar,5Popma JJ Deeb GM Yakubov SJ et al.Transcatheter aortic-valve replacement with a self-expanding valve in low-risk patients.N Engl J Med. 2019; 380 (doi:10.1056/NEJMoa1816885.): 1706-1715Google Scholar The optimal implant technique and THV design that will facilitate reproducible future coronary access and repeat TAVR procedures are currently unknown. Up to 50% of patients undergoing TAVR have concomitant coronary artery disease (CAD). The implications of CAD for clinical outcomes and the need to perform revascularization and its timing are poorly understood.6Faroux L Guimaraes L Wintzer-Wehekind J et al.Coronary artery disease and transcatheter aortic valve replacement: JACC state-of-the-art review.J Am Coll Cardiol. 2019; 74 (doi:10.1016/j.jacc.2019.06.012.): 362-372Google Scholar The large (n = 4000) multicenter COMPLETE TAVR (A Randomized, Comparative Effectiveness Study of Staged Complete Revascularization with Percutaneous Coronary Intervention to Treat Coronary Artery Disease vs Medical Management Alone in Patients with Symptomatic Aortic Valve Stenosis undergoing Elective Transfemoral Transcatheter Aortic Valve Replacement) trial will further assess this question by assessing whether, on a background of guideline-directed medical therapy, a strategy of complete revascularization involving staged percutaneous intervention (PCI) using drug eluting stents to treat all suitable coronary artery lesions is superior to a strategy of medical therapy alone in improving outcomes in patients who have undergone successful elective transfemoral Transcatheter Aortic Valve Replacement with a balloon expandable transcatheter heart valve (Edwards Lifesciences, Irvine, CA). The presence of a THV may pose unique challenges for future coronary angiography or PCI. Factors that may influence coronary access include patient anatomy, THV design features, and the position and deployment of the initial THV. The optimal timing of PCI, either before or after TAVR, in patients with concomitant coronary artery disease is also unknown and has important technical implications. A number of different commercially available THV designs are available. Each has its own unique frame and leaflet position. Some designs may pose challenges to performing coronary angiography or PCI after TAVR.7Yudi MB Sharma SK Tang GHL Coronary Angiography KA Percutaneous coronary intervention after transcatheter aortic valve replacement.J Am Coll Cardiol. 2018; 71 (doi:10.1016/j.jacc.2018.01.057.): 1360-1378Google Scholar While some THV designs have large cells that may facilitate coronary access, commissural alignment remains a challenge and the struts of the frame may lie in front of the coronary ostium and prevent optimal coronary access. Therefore, positioning of the initial TAVR valve so that either the top of the frame lies below the coronary ostium or in the case of a tall frame valve, ensuring that the base of the leaflet insertion is below the coronary ostium, may be desirable to facilitate future coronary access. Achieving this desired goal may require a lower implantation in some patients. A lower implantation may also be desirable in selected cases to facilitate future repeat procedures. Similar to valve-in-valve TAVR in failed surgical valves, repeat TAVR has potential risks of coronary obstruction and impaired coronary access. When a new THV valve is implanted, the leaflets of the failed THV are pushed up against of the frame and create a “neoskirt”. The neoskirt includes the skirt of the THV but also the leaflets of the failed THV which have now been pushed up and jailed between the frames of the failed and new THV. This neoskirt may lead to coronary obstruction or prevent coronary access. A lower implantation of the initial THV may favorably lower the height of the neoskirt and thus mitigate complications at the time of repeat TAVR. Until recently, successful implantation of the THV without any immediate or mid-term complications was appropriately considered a success. However, TAVR has evolved into a mature procedure and it is crucial that implantation be tailored to each patient to achieve optimal results. This may require varying implantation techniques based on patient factors and anatomy. Mitigating new PPM implantation will remain a priority but a desired “high” implantation depth must be balanced against other increasing concerns such as coronary access and repeat TAVR procedures. Ultimately, there may not be one “perfect” implantation depth, but rather one that is perfect for each individual patient. The authors have no funding to report.

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